Operating System
An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
An operating system performs these services for applications:
In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.
It manages the sharing of internal memory among multiple applications.
It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.
It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.
All major computer platforms (hardware and software) require and sometimes include an operating system. Linux, Windows 2000, VMS, OS/400, AIX, and z/OS are all examples of operating systems.
The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure those different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating Systems are classified according to the following parameters: -
- Multi-user: Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
- Multiprocessing: Supports running a program on more than one CPU.
- Multitasking: Allows more than one program to run concurrently.
- Multithreading: Allows different parts of a single program to run concurrently.
- Real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, are not real-time
Types of OS:
DOS
DOS (Disk Operating System) was the first widely installed operating system for personal computers. (Earlier, the same name had been used for an IBM operating system for a line of business computers.)
The first personal computer version of DOS, called PC-DOS, was developed for IBM by Bill Gates and his new Microsoft Corporation. He retained the rights to market a Microsoft version, called MS-DOS. PC-DOS and MS-DOS are almost identical and most users have referred to either of them as just "DOS." DOS was (and still is) a non-graphical line-oriented command- or menu-driven operating system, with a relatively simple interface but not overly "friendly" user interface. Its prompt to enter a command looks like this: C:>
The first Microsoft Windows operating system was really an application that ran on top of the MS-DOS operating system. Today, Windows operating systems continue to support DOS (or a DOS-like user interface) for special purposes by emulating the operating system.
In the 1970s before the personal computer was invented, IBM had a different and unrelated DOS (Disk Operating System) that ran on smaller business computers. It was replaced by IBM's VSE operating system.
Unix (often spelled "UNIX," especially as an official trademark) is an operating system that originated at Bell Labs in 1969 as an interactive time-sharing system. Ken Thompson and Dennis Ritchie are considered the inventors of Unix. The name (pronounced YEW-nihks) was a pun based on an earlier system, Multics. In 1974, Unix became the first operating system written in the C language. Unix has evolved as a kind of large freeware product, with many extensions and new ideas provided in a variety of versions of Unix by different companies, universities, and individuals.
Partly because it was not a proprietary operating system owned by any one of the leading computer companies and partly because it is written in a standard language and embraced many popular ideas, Unix became the first open or standard operating system that could be improved or enhanced by anyone. A composite of the C language and shell (user command) interfaces from different versions of Unix were standardized under the auspices of the IEEE as the Portable Operating System Interface (POSIX). In turn, the POSIX interfaces were specified in the X/Open Programming Guide 4.2. These interfaces are also known as the "Single UNIX Specification" and, in the most recent version, "UNIX 03"). The The Open Group, an industry standards organization, which certifies and brands Unix implementations, now owns the trademarked “UNIX”.
Unix operating systems are used in widely sold workstation products from Sun Microsystems, Silicon Graphics, IBM, and a number of other companies. The Unix environment and the client/server program model were important elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. R a Unix derivative available in both "free software" and commercial versions, is increasing in popularity as an alternative to proprietary operating systems
Windows OS
Windows is a personal computer operating system from Microsoft that, together with some commonly used business applications such as Microsoft Word and Excel, has become a de facto "standard" for individual users in most corporations as well as in most homes.
The original 1985 version of Windows introduced to home and business PC users many of the graphical user interface (GUI) ideas that were developed at an experimental lab at Xerox and introduced commercially by Apple's Lisa and Macintosh computers. Some of the well-known versions of Windows have included:
- Windows 95
- Windows 98
- Windows NT
- Windows 2000
- Windows XP
With the advent of the Internet, Microsoft has repositioned Windows as a kind of "window to the world," and its efforts to take the lead in Web browsers have made Internet Explorer the most popular browser. Microsoft's . NET initiative represents an attempt to become industry-dominant in furnishing products and services that facilitate the use of remote application services on the Web.
Win95 OS
A major release of the Microsoft Windows operating system released in 1995. Windows 95 represents a significant advance over its precursor, Windows 3.1. In addition to sporting a new user interface, Windows 95 also includes a number of important internal improvements. Perhaps most important, it supports 32-bit applications, which means that applications written specifically for this operating system should run much faster. And although Windows 95 can run older Windows and DOS applications, it has essentially removed DOS as the underlying platform. This has meant removal of many of the old DOS limitations, such as 640K of main memory and 8-character filenames.
Win98 OS
Originally it was called
Windows 98 offers support for a number of new technologies, including FAT32, AGP, MMX, USB, DVD, and ACPI. Its most visible feature, though, is the Active Desktop, which integrates the Web browser (Internet Explorer) with the operating system. From the user's point of view, there is no difference between accessing a document residing locally on the user's hard disk or on a Web server halfway around the world
Windows NT OS
Windows NT is a Microsoft Windows personal computer operating system designed for users and businesses needing advanced capability. NT's technology is the base for the Microsoft successor operating system, Windows 2000. Windows NT (which may originally have stood for "New Technology," although Microsoft doesn't say) is actually two products: Microsoft NT Workstation and Microsoft NT Server. The Workstation is designed for users, especially business users, who need faster performance and a system a little more fail-safe than Windows 95 and Windows 98. The Server is designed for business machines that need to provide services for network-attached computers. The Server is required, together with an Internet server such as Microsoft's Internet Information Server (IIS), for a Windows system that plans to serve Web pages.
Windows NT Workstation: Microsoft says that 32-bit applications run 20% faster on this system than on Windows 95 (assuming both have 32 megabytes of RAM). Since older 16-bit applications run in a separate address space, one can crash without crashing other applications or the operating system. Security and management features not available on Windows 95 are provided. The Workstation has the same desktop user interface as Windows 95.
Windows NT Server
The NT Server is probably the second most installed network server operating system after Novell's NetWare operating system. Microsoft claims that its NT servers are beginning to replace both NetWare and the various Unix-based systems such as those of Sun Microsystems and Hewlett-Packard. NT Server 5.0. essentially became what was renamed Windows 2000. Notable features of the Windows 2000 products are:
A fully customizable administrative console that can be based on tasks rather than files, applications, or users.
A new file directory approach called Active Directory that lets the administrator and other users view every file and application in the network from a single point-of-view.
Dynamic Domain Name Server (DNS), which replicates changes in the network using the Active Directory Services, the Dynamic Host Configuration Protocol (DHCP), and the Windows Internet Naming Service (WINS) whenever a client is reconfigured.
The ability to create, extend, or mirror a disk volume without having to shut down the system and to back up data to a variety of magnetic and optical storage media.
A Distributed File System (DFS) that lets users see a distributed set of files in a single file structure across departments, divisions, or an entire enterprise.
Close integration with and support for Microsoft's Message Queue Server, Microsoft Transaction Server, and Internet Information Server (IIS).
WinXP
An operating system introduced in 2001 from Microsoft's Windows family of operating systems, the previous version of Windows being Windows Me. Microsoft called the release its most important product since Windows 95. Along with a redesigned look and feel to the user interface, the new operating system is built on the Windows 2000 kernel, giving the user a more stable and reliable environment than previous versions of Windows. Windows XP comes in two versions, Home and Professional. The company has focused on mobility for both editions, including plug and play features for connecting to wireless networks. The operating system also utilizes the 802.11x wireless security standard.
The "XP" in Windows XP stands for "eXPerience."
Linux
Linux (often pronounced LIH-nuhks with a short "i") is an Unix-like operating system that was designed to provide personal computer users a free or very low-cost operating system comparable to traditional and usually more expensive Unix systems. Linux has a reputation as a very efficient and fast-performing system. Linux's kernel (the central part of the operating system) was developed by Linus Torvalds at the
Linux is a remarkably complete operating system, including a graphical user interface, an X Window System, TCP/IP, the Emacs editor, and other components usually found in a comprehensive Unix system. Although various creators of Linux’s components hold copyrights, Linux is distributed using the Free Software Foundation's copy left stipulations that mean any modified version that is redistributed must in turn be freely available.
Unlike Windows and other proprietary systems, Linux is publicly open and extendible by contributors. Because it conforms to the Portable Operating System Interface standard user and programming interfaces, developers can write programs that can be ported to other operating systems. Linux comes in versions for all the major microprocessor platforms including the Intel, PowerPC, Sparc, and Alpha platforms. It's also available on IBM's S/390. Linux is distributed commercially by a number of companies. A magazine, Linux Journal, is published as well as a number of books and pocket references.
Linux is sometimes suggested as a possible publicly developed alternative to the desktop predominance of Microsoft Windows. Although Linux is popular among users already familiar with Unix, it remains far behind Windows in numbers of users. However, its use in the business enterprise is growing.
Linux is a contraction for Linus' Unix; the short i sound preferred by most (including Torvalds) derives from the Swedish pronunciation of Linus
Mac OS
Mac OS is the computer operating system for Apple Computer's Macintosh line of personal computers and workstations. A popular feature of its latest version, Mac OS X, is a desktop interface with some 3-D appearance characteristics. OS X has a modular design intended to make it easier to add new features to the operating system in the future. It runs Unix applications as well as older Mac applications.
Mac OS comes with Apple Computer's iMac and Power Macintosh line of computers.
Palm OS
Palm OS is the computer operating system that provides a software platform for the Palm series of handheld personal digital assistants (PDAs) made by Palm Inc. According to Palm, Palm OS was designed from the beginning to fit into a palm-size device of a specific size and with a specific display size. Microsoft's Windows CE and Symbian's EPOC (originated by Psion) are also operating systems for handheld devices, but are designed to serve a broader range of devices.
Palm OS uses multitasking, but only one task is for applications. The user uses one application at a time; one application program must finish before the next can be selected. This constraint allows the operating system to devote full attention to the application that is open. The space needed by the system for any application that is running is kept in dynamic, reusable random access memory (RAM). The application and its related database are kept in what is called permanent storage, but here the permanent storage is RAM (rather than a hard disk) that cannot be reused as the dynamic RAM can. Palm OS divides an application into run able code and different types of data elements, such as user interface elements and icons. The data elements can be easily changed without necessarily having to rewrite code.
Palm OS comes with these applications built-in: Dates, Address Book, To Do Lis, Memo Pad, Calculator, and Password Protection. New applications can be written and added using several facilities that accelerate development.
Palm supports Metrowerks' CodeWarrior as the official software development kit (SDK), using a Macintosh or Windows environment. Unix platform users can use a kit called GCC, which is available through the Free Software Foundation. Programmers can use C, C++, assembler, or scripting. The Palm user interface is emulated within a window in the desktop environment, encouraging rapid application development. Simpler applications can be developed using Palm's forms interface.
Palm OS comes with communication interfaces to infrared transmission devices, TCP/IP (for Web connection through wireless or wireline devices), and, optionally, barcode recognition scanners.
Z OS
Z/OS is the computer operating system for IBM's zSeries 900 (z900) line of large (mainframe) servers. Z/OS is a renamed and upgraded version of OS/390, which in turn evolved from the MVS operating system. IBM's renamed servers and operating systems reflect a strategy to realign its products more closely with the Internet and its own e-business initiatives.
Z/OS is described as an extremely scalable and secure high-performance operating system based on the 64-bit z/Architecture. Like its predecessor, OS/390, z/OS lays claim to being highly reliable for running mission-critical applications. The operating system supports Web- and Java-based applications.
Novell
NDS (Novell Directory Services) is a popular software product for managing access to computer resources and keeping track of the users of a network, such as a company's intranet, from a single point of administration. Using NDS, a network administrator can set up and control a database of users and manage them using a directory with an easy-to-use graphical user interface (GUI). Users of computers at remote locations can be added, updated, and managed centrally. Applications can be distributed electronically and maintained centrally.
NDS can be installed to run under Windows NT, Sun Microsystems’s Solaris, and IBM's OS/390 as well as under Novell's own NetWare so that it can be used to control a multi-platform network. NDS is generally considered an industry benchmark against which other products, such as Microsoft's Active Directory, must compete.
Citrix Metaframe Server
MetaFrame is the name for a thin client/server software application from Citrix that is used to provide Microsoft's Windows Terminal Server product (WTS) with additional server and client functionality by allowing any client, no matter what operating system (OS) they are using, to connect to a Windows Terminal Server and run a Windows application through their browser. MetaFrame is useful for its ability to "load balance" by automatically directing a client to the server with the lightest load in a server farm, and its ability to allow publishing and application management from a single server in that farm. MetaFrame also features a secure encryption option through a distributed Windows presentation protocol developed by Citrix, called
Types of Application
Applications can be classified on the basis of platform, which are as follows: -
Desktop Applications
A desktop application system allows you to use different typefaces, specify various margins and justifications, and embed illustrations and graphs directly into the text. The most powerful desktop applications enable you to create illustrations, while less powerful systems let you insert illustrations created by other programs.
As word-processing programs become more and more powerful, the line separating such programs from desktop publishing systems is becoming blurred. In general, though, desktop publishing applications give you more control over typographical characteristics, such as kerning, and provide more support for full-color output.
A particularly important feature of desktop applications is that they enable you to see on the display screen exactly how the document will appear when printed. Systems that support this feature are called WYSIWYGs (what you see is what you get).
Web Applications
A Web application is a dynamic extension of a Web server. There are two types of Web applications, which are mentioned as follows: -
Presentation-oriented
A presentation-oriented Web application generates dynamic Web pages containing various types of markup language (HTML, XML, and so on) in response to requests.
Service-oriented
A service-oriented Web application implements the endpoint of a fine-grained Web service. Service-oriented Web applications are often invoked by presentation-oriented applications.
In the Java 2 Platform, Web components provide the dynamic extension capabilities for a Web server. Web components are either Java Servlets or JSP pages. Servlets are Java programming language classes that dynamically process requests and construct responses. JSP pages are text-based documents that execute as servlets but allow a more natural approach to creating static content. Although servlets and JSP pages can be used interchangeably, each has its own strengths. Servlets are best suited to service-oriented Web applications and managing the control functions of a presentation-oriented application, such as dispatching requests and handling nontextual data. JSP pages are more appropriate for generating text-based markup such as HTML, SVG, WML, and XML.
Web components are supported by the services of a runtime platform called a Web container. In the Java Web Services Developer Pack (Java WSDP) Web components run in the Tomcat Web container. The Web container provides services such as request dispatching, security, concurrency, and life cycle management. It also gives Web components access to APIs such as naming, transactions, and e-mail.
Embedded Applications
An embedded system is some combination of computer hardware and software, either fixed in capability or programmable, which is specifically designed for a particular kind of application device. Industrial machines, automobiles, medical equipment, cameras, household appliances, airplanes, vending machines, and toys (as well as the more obvious cellular phone and PDA) are among the myriad possible hosts of an embedded system. Embedded systems that are programmable are provided with a programming interface, and embedded systems programming is a specialized occupation.
Certain operating systems or language platforms are tailored for the embedded market, such as EmbeddedJava and Windows XP Embedded. However, some low-end consumer products use very inexpensive microprocessors and limited storage, with the application and operating system both part of a single program. The program is written permanently into the system's memory in this case, rather than being loaded into RAM (random access memory), as programs on a personal computer are.
EAI (enterprise application integration) is a business computing term for the plans, methods, and tools aimed at modernizing, consolidating, and coordinating the computer applications in an enterprise. Typically, an enterprise has existing legacy applications and databases and wants to continue to use them while adding or migrating to a new set of applications that exploit the Internet, e-commerce, extranet, and other new technologies. EAI may involve developing a new total view of an enterprise's business and its applications, seeing how existing applications fit into the new view, and then devising ways to efficiently reuse what already exists while adding new applications and data.
EAI encompasses methodologies such as object-oriented programming, distributed, cross-platform program communication using message brokers with Common Object Request Broker Architecture and COM+, the modification of enterprise resource planning (ERP) to fit new objectives, enterprise-wide content and data distribution using common databases and data standards implemented with the Extensible Markup Language (XML), middleware, message queuing, and other approaches.
System Applications
A program or group of programs designed for end users. Software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources.
In contrast, applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.
Wireless application service provider (WASP) is part of a growing industry sector resulting from the convergence of two trends: wireless communications and the outsourcing of services. A WASP performs the same service for wireless clients as a regular application service provider (ASP) does for wired clients: it provides Web-based access to applications and services that would otherwise have to be stored locally. The main difference with WASP is that it enables customers to access the service from a variety of wireless devices, such as a smartphone or personal digital assistant (PDA).
Although the business world is increasingly mobile, many corporations are resisting the idea of wireless communication, because of concerns about set-up and maintenance costs and the need for in-house expertise. WASPs offer businesses the advantages of wireless service with less expense and fewer risks. Because mobile applications are subscribed to, rather than purchased, up-front costs are lower; because the WASP provides support, staffing and training costs are lower.
WASP services may include:
- Constant system monitoring
- Diagnostics and resolution
- User support
- Text formatting for various devices
- Problem detection and reporting
Server
Server is a computer on a network that is dedicated to a particular purpose and which stores all information and performs the critical functions for that purpose. For example, a Web server would store all files related to a Web site and perform all work necessary for hosting the Web site. Most congressional offices have at least one server that is dedicated as both a network server and a file server. This means that, in it's network server role, the computer is responsible for holding the files and managing the processes that enable everyone in the office to access and use the network. In it's file server role, it holds the central computer files and the CMS database.
As the name implies, a server serves information to computers that connect to it. When users connect to a server, they can access programs, files, and other information from the server Common servers is Web servers, mail servers, and LAN servers. A single computer can have several different server programs running on it.
Application Server
An application server is a server program in a computer in a distributed network that provides the business logic for an application program. The application server is frequently viewed as part of a three-tier application, consisting of a graphical user interface (GUI) server, an application (business logic) server, and a database and transaction server. More descriptively, it can be viewed as dividing an application into:
A first-tier, front-end, Web browser-based graphical user interface, usually at a personal computer or workstation
A middle-tier business logic application or set of applications, possibly on a local area network or intranet server
A third-tier, back-end, database and transaction server, sometimes on a mainframe or large server
Older, legacy application databases and transaction management applications are part of the back end or third tier. The application server is the middleman between browser-based front-ends and back-end databases and legacy systems.
In many usages, the application server combines or works with a Web (Hypertext Transfer Protocol) server and is called a Web application server. The Web browser supports an easy-to-create HTML-based front-end for the user. The Web server provides several different ways to forward a request to an application server and to forward back a modified or new Web page to the user. These approaches include the Common Gateway Interface (CGI), FastCGI, Microsoft's Active Server Page, and the Java Server Page. In some cases, the Web application servers also support request "brokering" interfaces such as CORBA Internet Inter-ORB Protocol (IIOP).
Web Server
A Web server is a program that, using the client/server model and the World Wide Web's Hypertext Transfer Protocol (HTTP), serves the files that form Web pages to Web users (whose computers contain HTTP clients that forward their requests). Every computer on the Internet that contains a Web site must have a Web server program. Two leading Web servers are Apache, the most widely installed Web server, and Microsoft's Internet Information Server (IIS). Other Web servers include Novell's Web Server for users of its NetWare operating system and IBM's family of Lotus Domino servers, primarily for IBM's OS/390 and AS/400 customers.
Web servers often come as part of a larger package of Internet- and intranet-related programs for serving e-mail, downloading requests for File Transfer Protocol (FTP) files, and building and publishing Web pages. Considerations in choosing a Web server include how well it works with the operating system and other servers, its ability to handle server-side programming, security characteristics, and publishing, search engine, and site building tools that may come with it.
FTP Server
A computer responsible for serving any kind of files, via the FTP protocol to ftp clients, which can also web browsers;
A software program that implements the FTP protocol and is working as a daemon serving any kind of files.
Proxy Server
A proxy server is a server that acts as an intermediary between a workstation user and the Internet so that the enterprise can ensure security, administrative control, and caching service. A proxy server is associated with or part of a gateway server that separates the enterprise network from the outside network and a firewall server that protects the enterprise network from outside intrusion.
A proxy server receives a request for an Internet service (such as a Web page request) from a user. If it passes filtering requirements, the proxy server, assuming it is also a cache server, looks in its local cache of previously downloaded Web pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.
To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server. (The proxy is not quite invisible; its IP address has to be specified as a configuration option to the browser or other protocol program.)
An advantage of a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy's cache, which will improve user response time. In fact, there are special servers called cache servers. A proxy can also do logging.
The functions of proxy, firewall, and caching can be in separate server programs or combined in a single package. Different server programs can be in different computers. For example, a proxy server may in the same machine with a firewall server or it may be on a separate server and forward requests through the firewall.
File Server
In the client/server model, a file server is a computer responsible for the central storage and management of data files so that other computers on the same network can access the files. A file server allows users to share information over a network without having to physically transfer files by floppy diskette or some other external storage device. Any computer can be configured to be a host and act as a file server. In its simplest form, a file server may be an ordinary PC that handles requests for files and sends them over the network. In a more sophisticated network, a file server might be a dedicated network-attached storage (NAS) device that also serves as a remote hard disk drive for other computers, allowing anyone on the network to store files on it as if to their own hard drive.
Internet Information Server (IIS)
IIS (Internet Information Server) is a group of Internet servers (including a Web or Hypertext Transfer Protocol server and a File Transfer Protocol server) with additional capabilities for Microsoft's Windows NT and Windows 2000 Server operating systems. IIS is Microsoft's entry to compete in the Internet server market that is also addressed by Apache, Sun Microsystems, O'Reilly, and others. With IIS, Microsoft includes a set of programs for building and administering Web sites, a search engine, and support for writing Web-based applications that access databases. Microsoft points out that IIS is tightly integrated with the Windows NT and 2000 Servers in a number of ways, resulting in faster Web page serving.
A typical company that buys IIS can create pages for Web sites using Microsoft's Front Page product (with its WYSIWYG user interface). Web developers can use Microsoft's Active Server Page (ASP) technology, which means that applications - including ActiveX controls - can be imbedded in Web pages that modify the content sent back to users. Developers can also write programs that filter requests and get the correct Web pages for different users by using Microsoft's Internet Server Application Program Interface (ISAPI) interface. ASPs and ISAPI programs run more efficiently than common gateway interface (CGI) and server-side include (SSI) programs, two current technologies. (However, there are comparable interfaces on other platforms.)
Microsoft includes special capabilities for server administrators designed to appeal to Internet service providers (ISPs). It includes a single window (or "console") from which all services and users can be administered. It's designed to be easy to add components as snap-ins that you didn't initially install. Individual customers can customize the administrative windows for access. Microsoft has been criticized for IIS's susceptibility to computer virus attacks such as Code Red and Nimda.
Microsoft Internet Security And Acceleration Server (MS-ISA)
Microsoft's ISA Server (Internet Security and Acceleration Server) is the successor to Microsoft's Proxy Server 2.0 (see proxy server) and is part of Microsoft's .NET support. ISA Server provides the two basic services of an enterprise firewall and a Web proxy/cache server. ISA Server's firewall screens all packet-level, circuit-level, and application-level traffic. The Web cache stores and serves all regularly accessed Web content in order to reduce network traffic and provide faster access to frequently accessed Web pages. ISA Server also schedules downloads of Web page updates for non-peak times.
ISA Server allows administrators to create policies for regulating usage based on user, group, application, destination, schedule, and content type criteria. ISA Server is designed to work with Windows 2000 and later operating systems and to take advantage of Windows' Kerberos security. ISA Server includes a software development kit (SDK).
SMS Server
SMS Server is an efficient tool that makes sending and receiving SMS messages from a computer easy. It uses a GSM phone connected to the PC with a phone-to-pc data cable. The software can be used as a stand-alone SMS communicator or can be attached to other systems to accomplish automatic messaging.
RIS Server
Remote Installation Service (RIS) is a feature included in Microsoft's Windows 2000 server that allows network administrators to install the Windows 2000 Professional operating system and its upgrades to any number of client computers at one time from a centralized location. If the client computer is connected to the server through a local area network (LAN), the computer's hardware will find the RIS server and request a copy of the operating system. The network administrator can use the RISrep imaging option to copy several versions, or images, of a company's desktop configuration to the server so that if a request is made, the server can issue an "image" for a particular computer or user. Microsoft promotes the use of RIS as a way to configure new computers right out of the box and to restore the operating system on a computer that has failed.
Apache Server
Apache is a freely available Web server that is distributed under an "open source" license. Version 2.0 runs on most Unix-based operating systems (such as Linux, Solaris, Digital UNIX, and AIX), on other UNIX/POSIX-derived systems (such as Rhapsody, BeOS, and BS2000/OSD), on AmigaOS, and on Windows 2000.
Technologies
Java
Java is a programming language expressly designed for use in the distributed environment of the Internet. It was designed to have the "look and feel" of the C++ language, but it is simpler to use than C++ and enforces an object-oriented programming model. Java can be used to create complete applications that may run on a single computer or be distributed among servers and clients in a network. It can also be used to build a small application module or applet for use as part of a Web page. Applets make it possible for a Web page user to interact with the page.
The major characteristics of Java are:
The programs you create are portable in a network.
Your source program is compiled into what Java calls byte code, which can be run anywhere in a network on a server or client that has a Java virtual machine.
The Java virtual machine interprets the byte code into code that will run on the real computer hardware.
This means that individual computer platform differences such as instruction lengths can be recognized and accommodated locally just as the program is being executed.
Platform-specific versions of your program are no longer needed.
The code is robust, here meaning that, unlike programs written in C++ and perhaps some other languages, the Java objects can contain no references to data external to themselves or other known objects.
This ensures that an instruction cannot contain the address of data storage in another application or in the operating system itself, either of which would cause the program and perhaps the operating system itself to terminate or "crash."
The Java virtual machine makes a number of checks on each object to ensure integrity.
Java is object-oriented, which means that, among other characteristics, an object can take advantage of being part of a class of objects and inherit code that is common to the class. Objects are thought of as "nouns" that a user might relate to rather than the traditional procedural "verbs." A method can be thought of as one of the object's capabilities or behaviors.
In addition to being executed at the client rather than the server, a Java applet has other characteristics designed to make it run fast.
Relative to C++, Java is easier to learn. (However, it is not a language you'll pick up in an evening!)
Java was introduced by Sun Microsystems in 1995 and instantly created a new sense of the interactive possibilities of the Web. Both of the major Web browsers include a Java virtual machine. Almost all major operating system developers (IBM, Microsoft, and others) have added Java compilers as part of their product offerings.
The Java virtual machine includes an optional just-in-time compiler that dynamically compiles byte code into executable code as an alternative to interpreting one byte code instruction at a time. In many cases, the dynamic JIT compilation is faster than the virtual machine interpretation.
JavaScript should not be confused with Java. JavaScript, which originated at Netscape, is interpreted at a higher level, is easier to learn than Java, but lacks some of the portability of Java and the speed of byte code. Because Java applets will run on almost any operating system without requiring recompilation and because Java has no operating system-unique extensions or variations, Java is generally regarded as the most strategic language in which to develop applications for the Web. (However, JavaScript can be useful for very small applications that run on the Web client or server.)
JavaScript
JavaScript is an interpreted programming or script language from Netscape. It is somewhat similar in capability to Microsoft's Visual Basic, Sun's Tcl, the UNIX-derived Perl, and IBM's Rexx. In general, script languages are easier and faster to code in than the more structured and compiled languages such as C and C++. Script languages generally take longer to process than compiled languages, but are very useful for shorter programs.
JavaScript is used in Web site development to do such things as:
- Automatically change a formatted date on a Web page
- Cause a linked-to page to appear in a popup window
- Cause text or a graphic image to change
VBScript
VBScript is an interpreted script language from Microsoft that is a subset of its Visual Basic programming language designed for interpretation by Web browsers.
VBScript is Microsoft's answer to Netscape's popular JavaScript. Both are designed to work with an interpreter that comes with a Web browser - that is, at the user or client end of the Web client/server session. VBScript is designed for use with Microsoft's Internet Explorer browser together with other programming that can be run at the client, including ActiveX controls, automation servers, and Java applets. Although Microsoft does support Netscape's JavaScript (it converts it into its own JScript), Netscape does not support VBScript. For this reason, VBScript is best used for intranet Web sites that use the Internet Explorer browser only.
Perl
Perl was originally said to stand for "Practical Extraction and Reporting Language" but that name is no longer used. Perl is a script programming language that is similar in syntax to the C language and that includes a number of popular Unix facilities such as SED, awk, and tr. Perl is an interpreted language that can optionally be compiled just before execution into either C code or cross-platform byte code. When compiled, a Perl program is almost (but not quite) as fast as a fully precompiled C language program. Perl is regarded as a good choice for developing common gateway interface (CGI) programs because it has good text manipulation facilities (although it also handles binary files). Larry Wall invented it.
Microsoft Front Page
FrontPage 2000, part of the Microsoft Office 2000 Premium package, allows you to create engaging Web sites that look and work exactly the way you want them to. FrontPage includes the ability to lay out pages with exacting care, design the pages with elements that color-coordinate, and use such cutting-edge features as dynamic HTML (DHTML) and cascading style sheets, which add style, movement, and interest to Web pages. The FrontPage Explorer, which is integrated into FrontPage 2000, makes it easy to manage the pages and the navigation structure of your Web site.
FrontPage also includes publishing features that make it easy to post your site to your Web server, as well as collaboration features. Because FrontPage 2000 preserves all foreign HTML, including formatting, you can use FrontPage 2000 to edit and enhance data access pages without any loss of functionality.
Cascading Style Sheets
A cascading style sheet (CSS) is a Web page derived from multiple sources with a defined order of precedence where the definitions of any style element conflict. The Cascading Style Sheet, level 1 (CSS1) recommendation from the World Wide Web Consortium (W3C), which is implemented in the latest versions of the Netscape and Microsoft Web browsers, specifies the possible style sheets or statements that may determine how a given element is presented in a Web page.
CSS gives more control over the appearance of a Web page to the page creator than to the browser designer or the viewer.
CorelDraw
Corel Draw is multi-media based application, instrumental in creation of graphics and animation.
Visual Basic For Applications (VBA)
A Visual Basic system included with Windows 95 applications and used for creating basic and customized programs.
Personal Home Page (PHP)
In Web programming, PHP is a script language and interpreter that is freely available and used primarily on Linux Web servers. PHP, originally derived from Personal Home Page Tools, now stands for PHP: Hypertext Preprocessor.
PHP is an alternative to Microsoft's Active Server Page (ASP) technology. As with ASP, the PHP script is embedded within a Web page along with its HTML. Before the page is sent to a user that has requested it, the Web server calls PHP to interpret and perform the operations called for in the PHP script.
Hyper Text Markup Language (HTML)
HTML 4.0 was the final version of the Hypertext Markup Language (HTML) before the Extensible Markup Language (XHTML) and remains the set of markup on which most large Web sites today are based. Like all HTML levels, HTML 4.0 was the official "recommendation" of the World Wide Web Consortium (W3C), the group that suggests industry standards for the Web.
Among new features introduced in HTML 4.0 were:
- The cascading style sheet, the ability to control Web page content at multiple levels
- The ability to create richer forms
- Support for frames (which is already supported by the major browsers)
- Enhancements for tables that make it possible to use captions to provide table content for Braille or speech users
- The capability to manage pages so that they can be distributed in different languages
In practice, the two leading browsers, Netscape and Internet Explorer, support HTML 4.0 somewhat differently or offer non-standard approaches. These require Web developers that use more advanced features to create pages for each browser and send the appropriate pages to the user
Java Server Pages (JSP)
Java Server Page (JSP) is a technology for controlling the content or appearance of Web pages through the use of servlets, small programs that are specified in the Web page and run on the Web server to modify the Web page before it is sent to the user who requested it. Sun Microsystems, the developer of Java, also refers to the JSP technology as the Servlet application program interface (API). JSP is comparable to Microsoft's Active Server Page (ASP) technology. Whereas a Java Server Page calls a Java program that is executed by the Web server, an Active Server Page contains a script that is interpreted by a script interpreter (such as VBScript or JScript) before the page is sent to the user.
Servlet
A servlet is a small program that runs on a server. The term was coined in the context of the Java applet, a small program that is sent as a separate file along with a Web (HTML) page. Java applets, usually intended for running on a client, can result in such services as performing a calculation for a user or positioning an image based on user interaction.
XML
XML (Extensible Markup Language) is a flexible way to create common information formats and share both the format and the data on the World Wide Web, intranets, and elsewhere. For example, computer makers might agree on a standard or common way to describe the information about a computer product (processor speed, memory size, and so forth) and then describe the product information format with XML. Such a standard way of describing data would enable a user to send an intelligent agent (a program) to each computer maker's Web site, gather data, and then make a valid comparison. Any individual or group of individuals or companies that wants to share information in a consistent way can use XML
Struts
Jakarta Struts, the premier framework for building Java-based Web applications. Using the model-view-controller (MVC) architecture, Struts solves many of the problems associated with developing Web applications using JavaServlets and JavaServer Pages. Consequently, costs are reduced and development time is enhanced through the re-use of software components and the implementation of a framework based on industry best practices.
J2EE
(Java 2 Platform, Enterprise Edition) is a Java platform designed for the mainframe-scale computing typical of large enterprises. Sun Microsystems (together with industry partners such as IBM) designed J2EE to simplify application development in a thin client tiered environment. J2EE simplifies application development and decreases the need for programming and programmer training by creating standardized, reusable modular components and by enabling the tier to handle many aspects of programming automatically.
J2EE includes many components of the Java 2 Platform, Standard Edition (J2SE):
The Java Development Kit (JDK) is included as the core language package.
Write Once Run Anywhere technology is included to ensure portability.
Support is provided for Common Object Request Broker Architecture (CORBA), a predecessor of Enterprise JavaBeans (EJB), so that Java objects can communicate with CORBA objects both locally and over a network through its interface broker.
Java Database Connectivity 2.0 (JDBC), the Java equivalent to Open Database Connectivity (ODBC), is included as the standard interface for Java databases.
A security model is included to protect data both locally and in Web-based applications.
J2EE also includes a number of components added to the J2SE model, such as the following:
- Full support is included for Enterprise JavaBeans.
- EJB is a server-based technology for the delivery of program components in an enterprise environment.
- It supports the Extensible Markup Language (XML) and has enhanced deployment and security features.
The Java servlet API (application programming interface) enhances consistency for developers without requiring a graphical user interface (GUI).
Java Server Pages (JSP) is the Java equivalent to Microsoft's Active Server Pages (ASP) and is used for dynamic Web-enabled data access and manipulation.
The J2EE architecture consists of four major elements:
- The J2EE Application Programming Model is the standard programming model used to facilitate the development of multi-tier, thin client applications.
- The J2EE Platform includes necessary policies and APIs such as the Java servlets and Java Message Service (JMS).
- The J2EE Compatibility Test Suite ensures that J2EE products are compatible with the platform standards.
- The J2EE Reference Implementation explains J2EE capabilities and provides its operational definition.
Weblogic
BEA Systems' WebLogic is a server software application that runs on a middle tier, between back-end databases and related applications and browser-based thin clients. WebLogic is a leading e-commerce online transaction-processing (OLTP) platform; developed to connect users in a distributed computing environment and to facilitate the integration of mainframe applications with distributed corporate data and applications.
WebLogic server is based on Java 2 Platform, Enterprise Edition (J2EE), the standard platform used to create Java-based multi-tier enterprise applications. J2EE platform technologies were developed through the efforts of BEA Systems and other vendors in collaboration with the main developer, Sun Microsystems. Because J2EE applications are standardized modules, WebLogic can automate many system-level tasks that would otherwise have demanded programming time.
The main features of WebLogic server include connectors that make it possible for any legacy application on any client to interoperate with server applications, Enterprise JavaBean (EJB) components, resource pooling, and connection sharing that make applications very scalable. An administration console with a user interface makes management tasks more efficient and features such as Secure Sockets Layer (SSL) support for the encryption of data transmissions, as well as authentication and authorization mechanisms, make applications and transactions secure.
WebSphere
WebSphere is a set of Java-based tools from IBM that allow customers to create and manage sophisticated business Web sites. The central WebSphere tool is the WebSphere Application Server (WAS), an application server that a customer can use to connect Web site users with Java applications or servlets. Servlets are Java programs that run on the server rather than on the user's computer as Java applets do. Servlets can be developed to replace traditional common gateway interface (CGI) scripts, usually written in C or Practical Extraction and Reporting Language, and run much faster because all user requests run in the same process space.
In addition to Java, WebSphere supports open standard interfaces such as the Common Object Request Broker Architecture (CORBA) and Java Database Connectivity (JDC) and is designed for use across different operating system platforms. One edition of WebSphere is offered for small-to-medium size businesses and another edition for larger businesses with a higher number of transactions. WebSphere also includes Studio, a developer's environment with additional components that allow a Web site's pages to be created and managed. Both editions support Solaris, Windows NT, OS/2, OS/390, and AIX operating systems.
Java Message Service (JMS)
Java Message Service (JMS) is an application program interface (API) from Sun Microsystems that supports the formal communication known as messaging between computers in a network. Sun's JMS provides a common interface to standard messaging protocols and also to special messaging services in support of Java programs. Sun advocates the use of the Java Message Service for anyone developing Java applications, which can be run from any major operating system platform.
The messages involved exchange crucial data between computers - rather than between users - and contain information such as event notification and service requests. Messaging is often used to coordinate programs in dissimilar systems or written in different programming languages.
Using the JMS interface, a programmer can invoke the messaging services of IBM's MQSeries, Progress Software's SonicMQ, and other popular messaging product vendors. In addition, JMS supports messages that contain serialized Java objects and messages that contain Extensible Markup Language (XML) pages.
J2ME: -
J2ME (Java 2 Platform, Micro Edition) is a technology that allows programmers to use the Java programming language and related tools to develop programs for mobile wireless information devices such as cellular phones and personal digital assistants (PDAs). J2ME consists of programming specifications and a special virtual machine, the K Virtual Machine that allows a J2ME-encoded program to run in the mobile device.
There are two programming specifications: Connected, Limited Device Configuration (CLDC) and the Mobile Information Device Profile (MIDP). CLDC lays out the application program interface (API) and virtual machine features needed to support mobile devices. MIDP adds to the CLDC the user interface, networking, and messaging details needed to interface with mobile devices. MIDP includes the idea of a midlet, a small Java application similar to an applet but one that conforms to CLDC and MIDP and is intended for mobile devices.
Devices with systems that exploit J2ME are already available and are expected to become even more available in the next few years.
Java Naming and Directory Interface (JNDI)
JNDI (Java Naming and Directory Interface) enables Java platform-based applications to access multiple naming and directory services. Part of the Java Enterprise application programming interface (API) set, JNDI makes it possible for developers to create portable applications that are enabled for a number of different naming and directory services, including: file systems; directory services such as Lightweight Directory Access Protocol (LDAP), Novell Directory Services, and Network Information System (NIS); and distributed object systems such as the Common Object Request Broker Architecture (CORBA), Java Remote Method Invocation (RMI), and Enterprise JavaBeans (EJB).
Common Object Request Broker Architecture (CORBA)
Common Object Request Broker Architecture (CORBA) is an architecture and specification for creating, distributing, and managing distributed program objects in a network. It allows programs at different locations and developed by different vendors to communicate in a network through an "interface broker." CORBA was developed by a consortium of vendors through the Object Management Group (OMG), which currently includes over 500 member companies. Both International Organization for Standardization (ISO) and X/Open have sanctioned CORBA as the standard architecture for distributed objects (which are also known as components). CORBA 3 is the latest level.
The essential concept in CORBA is the Object Request Broker (ORB). ORB support in a network of clients and servers on different computers means that a client program (which may itself be an object) can request services from a server program or object without having to understand where the server is in a distributed network or what the interface to the server program looks like. To make requests or return replies between the ORBs, programs use the General Inter-ORB Protocol (GIOP) and, for the Internet, it’s Internet Inter-ORB Protocol (IIOP). IIOP maps GIOP requests and replies to the Internet's Transmission Control Protocol (TCP) layer in each computer.
A notable holdout from CORBA is Microsoft, which has its own distributed object architecture, the Distributed Component Object Model (DCOM). However, CORBA and Microsoft have agreed on a gateway approach so that a client object developed with the Component Object Model will be able to communicate with a CORBA server (and vice versa).
Internet Inter-Orb Protocol (IIOP)
IIOP (Internet Inter-ORB Protocol) is a protocol that makes it possible for distributed programs written in different programming languages to communicate over the Internet. IIOP is a critical part of a strategic industry standard, the Common Object Request Broker Architecture (CORBA). Using CORBA's IIOP and related protocols, a company can write programs that will be able to communicate with their own or other company's existing or future programs wherever they are located and without having to understand anything about the program other than its service and a name. CORBA and IIOP are competing with a similar strategy from Microsoft called the Distributed Component Object Model (DCOM). (Microsoft and the Object Management Group, sponsors of CORBA, have agreed to develop software bridges between the two models so that programs designed for CORBA can communicate with programs designed for DCOM.
RMI (Remote Method Invocation)
RMI (Remote Method Invocation) is a way that a programmer, using the Java programming language and development environment, can write object-oriented programming in which objects on different computers can interact in a distributed network. RMI is the Java version of what is generally known as a remote procedure call (RPC), but with the ability to pass one or more objects along with the request. The object can include information that will change the service that is performed in the remote computer. Sun Microsystems, the inventors of Java, calls this "moving behavior." For example, when a user at a remote computer fills out an expense account, the Java program interacting with the user could communicate, using RMI, with a Java program in another computer that always had the latest policy about expense reporting. In reply, that program would send back an object and associated method information that would enable the remote computer program to screen the user's expense account data in a way that was consistent with the latest policy. The user and the company both would save time by catching mistakes early. Whenever the company policy changed, it would require a change to a program in only one computer.
Sun calls its object parameter-passing mechanism object serialization. An RMI request is a request to invoke the method of a remote object. The request has the same syntax as a request to invoke an object method in the same (local) computer. In general, RMI is designed to preserve the object model and its advantages across a network.
RMI is implemented as three layers:
- A stub program in the client side of the client/server relationship, and a corresponding skeleton at the server end. The stub appears to the calling program to be the program being called for a service. (Sun uses the term proxy as a synonym for stub.)
- A Remote Reference Layer that can behave differently depending on the parameters passed by the calling program. For example, this layer can determine whether the request is to call a single remote service or multiple remote programs as in a multicast.
- A Transport Connection Layer, which sets up and manages the request.
A single request travels down through the layers on one computer and up through the layers at the other end.
RMI is supplied as part of Sun Microsystems’s Java Development Kit (JDK).
Jini
Jini (pronounced DJEE-nee like the Arabic word for "magician") is a new idea that Sun Microsystems calls "spontaneous networking." Using the Jini architecture, users will be able to plug printers, storage devices, speakers, and any kind of device directly into a network and every other computer, device, and user on the network will know that the new device has been added and is available. Each plug gable device will define itself immediately to a network device registry. When someone wants to use or access the resource, his or her computer will be able to download the necessary programming from it to communicate with it. No longer will the special device support software known as a device driver need to be present in an operating system. The operating system will know about all accessible devices through the network registry.
Jini can be viewed as the next step after the Java programming language toward making a network look like one large computer. Jini promises to enable manufacturers to make devices that can attach to a network independently of an operating system like Windows 95. Equipped with its own small, special-purpose and possibly microchip-embedded operating system, a printer could be plugged into a network and immediately shared by users at a mix of computers: Windows, Macintosh, and UNIX. Mobile devices could be transported and easily plugged into a network so that others could use the device.
How It Works
Jini consists of four program layers:
- Directory Service
- JavaSpace
- Remote Method Invocation (RMI)
- Boot, Join, and Discover Protocol
Any device with an operating system that supports a Java can be plugged into the network. (For many devices, the operating system can be much smaller than Windows 2000, for example, since it is serving only the functions that device requires.) When a device is plugged into the Jini network, the Directory Service layer as a member of the network immediately registers it. Its necessary program objects are placed in a JavaSpace layer so that other network members can discover and download them when that network member wants to use the device. The actual communication with objects in JavaSpace is done using the Remote Method Invocation (RMI) interface and layer. The layer supporting the boot, join, and discover protocols enables devices, users, and applications to announce and register themselves and to discover others.
. Net Technologies
. NET is the Microsoft Web services strategy to connect information, people, systems, and devices through software. Integrated across the Microsoft platform, .NET technology provides the ability to quickly build, deploy, manage, and use connected, security-enhanced solutions with Web services. . NET-connected solutions enable businesses to integrate their systems more rapidly and in a more agile manner and help them realize the promise of information anytime, anywhere, on any device.
The Microsoft platform includes everything a business needs to develop and deploy a Web service-connected IT architecture: servers to host Web services, development tools to create them, applications to use them, and a worldwide network of more than 35,000 Microsoft Certified Partner organizations to provide support.
Microsoft .NET
Microsoft software for connecting information, people, systems, and devices. . NET provides XML-based interoperability and is being incorporated across Microsoft clients, servers, services, and tools. For example, products like Microsoft Windows and Microsoft Office will use .NET to connect with other systems and applications. For developers, .NET is manifested in the programming model delivered in the Microsoft .NET Framework.
Microsoft .NET Framework
An integral Windows component that enables building and running the next generation of software applications and Web services. It includes technologies for Web services and Web applications (ASP.NET), data access (ADO.NET), smart client applications (Windows Forms), and many others.
Microsoft Visual Studio .NET
An integrated development environment for helping developers to build scalable applications and Web services.
Distributed Component Object Model
Distributed Component Object Model (DCOM) is a programming model in which processing occurs in many different places (or nodes) around a network. Processing can occur wherever it makes the most sense, whether that is on a server, personal computer, handheld device, or other smart device. In contrast to the two-node system prevalent today (the client and the centralized server), Microsoft .NET uses distributed computing.
ASP.Net
ASP.NET (originally called ASP+) is the next generation of Microsoft's Active Server Page (ASP), a feature of their Internet Information Server (IIS). Both ASP and ASP.NET allow a Web site builder to dynamically build Web pages on the fly by inserting queries to a relational database in the Web page. ASP.NET is different than its predecessor in two major ways: it supports code written in compiled languages such as Visual Basic, C++, C#, and Perl, and it features server controls that can separate the code from the content, allowing WYSIWYG editing of pages. Although ASP.NET is not backwards compatible with ASP, it is able to run side by side with ASP applications. ASP.NET files can be recognized by their .asp extension.
Visual Basic .Net
Visual Basic .NET (VB.NET or VB .NET) is a version of Microsoft's Visual Basic that was designed, as part of the company's .NET product group, to make Web services applications easier to develop. According to Microsoft, VB .NET was reengineered, rather than released as VB 6.0 with added features, to facilitate making fundamental changes to the language. VB.NET is the first fully object-oriented programming (OOP) version of Visual Basic, and as such, supports OOP concepts such as abstraction, inheritance, polymorphism, and aggregation.
C
C is a structured, procedural programming language that has been widely used both for operating systems and applications and that has had a wide following in the academic community. Many versions of Unix-based operating systems are written in C. C has been standardized as part of the Portable Operating System Interface (POSIX).
With the increasing popularity of object-oriented programming, C is being rapidly replaced as "the" programming language by C++, a superset of the C language that uses an entirely different set of programming concepts, and by Java, a language similar to but simpler than C++, that was designed for use in distributed networks.
ActiveServerPages (ASP)
ASP is also an abbreviation for application service provider.
An Active Server Page (ASP) is an HTML page that includes one or more scripts (small-embedded programs) that are processed on a Microsoft Web server before the page is sent to the user. An ASP is somewhat similar to a server-side include or a common gateway interface (CGI) application in that all involve programs that run on the server, usually tailoring a page for the user. Typically, the script in the Web page at the server uses input received as the result of the user's request for the page to access data from a database and then builds or customizes the page on the fly before sending it to the requestor.
ASP is a feature of the Microsoft Internet Information Server (IIS), but, since the server-side script is just building a regular HTML page, it can be delivered to almost any browser. You can create an ASP file by including a script written in VBScript or JScript in an HTML file or by using ActiveX Data Objects (ADOs) program statements in the HTML file. You name the HTML file with the ".asp" file suffix. Microsoft recommends the use of the server-side ASP rather than a client-side script, where there is actually a choice, because the server-side script will result in an easily displayable HTML page. Client-side scripts (for example, with JavaScript) may not work as intended on older browsers.
For Web service applications, Microsoft provides a new version of ASP support called ASP.NET.
C++
C++ is an object-oriented programming (OOP) language that is viewed by many as the best language for creating large-scale applications. C++ is a superset of the C language. C++ is based on the paradigm of Object Oriented Programming (OOPS).
Visual C++
An application development tool developed by Microsoft for C++ programmers. Visual C++ supports object-oriented programming of 32-bit Windows applications with an integrated development environment (IDE), a C/C++ compiler, and a class library called the Microsoft Foundation Classes (MFC). The IDE includes an AppWizard, ClassWizard, and testing features to make programming easier
C#
C# (pronounced "C-sharp") is an object-oriented programming language from Microsoft that aims to combine the computing power of C++ with the programming ease of Visual Basic. C# is based on C++ and contains features similar to those of Java.
C# is designed to work with Microsoft's . NET platform. Microsoft's aim is to facilitate the exchange of information and services over the Web, and to enable developers to build highly portable applications. C# simplifies programming through its use of Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP) which allow access to a programming object or method without requiring the programmer to write additional code for each step. Because programmers can build on existing code, rather than repeatedly duplicating it, C# is expected to make it faster and less expensive to get new products and services to market.
Microsoft is collaborating with ECMA, the international standards body, to create a standard for C#. International Standards Organization (ISO) recognition for C# would encourage other companies to develop their own versions of the language. Companies that are already using C# include Apex Software, Bunka Orient, Component Source, devSoft, FarPoint Technologies, LEAD Technologies, ProtoView, and Seagate Software.
Web Services
Web services (sometimes called application services) are services (usually including some combination of programming and data, but possibly including human resources as well) that are made available from a business's Web server for Web users or other Web-connected programs. Providers of Web services are generally known as application service providers. Web services range from such major services as storage management and customer relationship management (CRM) down to much more limited services such as the furnishing of a stock quote and the checking of bids for an auction item. The accelerating creation and availability of these services is a major Web trend.
The three major components of Web Services are mentioned as below: -
SOAP (Simple Object Access Protocol)
Simple Object Access Protocol is a way for a program running in one kind of operating system (such as Windows 2000) to communicate with a program in the same or another kind of an operating system (such as Linux) by using the World Wide Web's Hypertext Transfer Protocol (HTTP) and its Extensible Markup Language (XML) as the mechanisms for information exchange. Since Web protocols are installed and available for use by all major operating system platforms, HTTP and XML provide an already at-hand solution to the problem of how programs running under different operating systems in a network can communicate with each other. SOAP specifies exactly how to encode an HTTP header and an XML file so that a program in one computer can call a program in another computer and pass it information. It also specifies how the called program can return a response.
SOAP was developed by Microsoft, DevelopMentor, and Userland Software and has been proposed as a standard interface to the Internet Engineering Task Force (IETF). It is somewhat similar to the Internet Inter-ORB Protocol (IIOP), a protocol that is part of the Common Object Request Broker Architecture (CORBA). Sun Microsystems' Remote Method Invocation (RMI) is a similar client/server interprogram protocol between programs written in Java.
An advantage of SOAP is that program calls are much more likely to get through firewall servers that screen out requests other than those for known applications (through the designated port mechanism). Since HTTP requests are usually allowed through firewalls, programs using SOAP to communicate can be sure that they can communicate with programs anywhere.
UDDI
UDDI (Universal Description, Discovery, and Integration) is an XML-based registry for businesses worldwide to list them on the Internet. Its ultimate goal is to streamline online transactions by enabling companies to find one another on the Web and make their systems interoperable for e-commerce. UDDI is often compared to a telephone book's white, yellow, and green pages. The project allows businesses to list themselves by name, product, location, or the Web services they offer.
Microsoft, IBM, and Ariba spearheaded UDDI. The project now includes 130 companies, including some of the biggest names in the corporate world. Compaq, American Express, SAP AG, and Ford Motor Company are all committed to UDDI, as is Hewlett-Packard, whose own XML-based directory approach, called e-speak, is now being integrated with UDDI.
While the group does not refer to itself as a standards body, it does offer a framework for Web services integration. The UDDI specification utilizes World Wide Web Consortium (W3C) and Internet Engineering Task Force (IETF) standards such as XML, HTTP, and Domain Name System (DNS) protocols. It has also adopted early versions of the proposed Simple Object Access Protocol (SOAP) messaging guidelines for cross platform programming.
In November 2000, UDDI entered its public beta-testing phase. Each of its three founders - Microsoft, IBM, and Ariba - now operates a registry server that is interoperable with servers from other members. As information goes into a registry server, servers in the other businesses share it. The UDDI beta is scheduled to end in the first quarter of 2001. In the future, other companies will act as operators of the UDDI Business Registry.
UDDI registration is open to companies worldwide, regardless of their size.
Database
A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.
In computing, databases are sometimes classified according to their organizational approach. The most prevalent approach is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and subclasses.
The various types of database applications are mentioned as follows: -
Database Management Systems (DBMS)
A database management system (DBMS), sometimes just called a database manager, is a program that lets one or more computer users create and access data in a database. The DBMS manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and, in a multi-user system, which else may also be accessing the data. In handling user requests, the DBMS ensures the integrity of the data (that is, making sure it continues to be accessible and is consistently organized as intended) and security (making sure only those with access privileges can access the data). The most typical DBMS is a relational database management system (RDBMS). A standard user and program interface is the Structured Query Language (SQL). A newer kind of DBMS is the object-oriented database management system (ODBMS).
A DBMS can be thought of as a file manager that manages data in databases rather than files in file systems. In IBM's mainframe operating systems, the nonrelational data managers were (and are, because these legacy application systems are still used) known as access methods.
A DBMS is usually an inherent part of a database product. On PCs, Microsoft Access is a popular example of a single- or small-group user DBMS. Microsoft's SQL Server is an example of a DBMS that serves database requests from multiple (client) users. Other popular DBMS’s (these are all RDBMS’s, by the way) are IBM's DB2, Oracle's line of database management products, and Sybase's products.
DBase
A popular database management system produced by Ashton Tate Corporation. The dBase format for storing data has become a de facto standard, and is supported by nearly all database management and spreadsheet systems. Even systems that do not use the dBase format internally are able to import and export data in dBase format.
MS-Access
Access is a database application package, where data is stored in tables. Data can be inserted, updated, deleted. It is extensively used as a back end application.
Sybase
Sybase is a computer software company that develops and sells database management system (DBMS) and middleware products. Sybase products have found extensive application, particularly in commercial, industrial, and military communications systems.
RDBMS (Relational Database Management System)
A relational database management system (RDBMS) is a program that lets you create, update, and administer a relational database. Most commercial RDBMS's use the Structured Query Language (SQL) to access the database, although SQL was invented after the development of the relational model and is not necessary for its use.
The leading RDBMS products are Oracle, IBM's DB2 and Microsoft's SQL Server. Despite repeated challenges by competing technologies, as well as the claim by some experts that no current RDBMS has fully implemented relational principles, the majority of new corporate databases are still being created and managed with an RDBMS.
Oracle
It is the world's leading supplier of software for information management but it is best known for its sophisticated relational database products (notably Oracle9i), which are used in Fortune 1000 corporations and by many of the largest Web sites. Oracle's relational database was the world's first to support the Structured Query Language (SQL), now an industry standard.
Oracle targets high-end workstations and minicomputers as the server platforms on which to run its database systems. Along with Sun Microsystems, Oracle has long been a champion of network computers. It now boasts that it was the world's first software company to develop and deploy 100 percent Internet-enabled enterprise software across its entire product line: database, server, enterprise business applications, and application development and decision support tools.
Structured Query Language (SQL)
SQL (Structured Query Language) is a standard interactive and programming language for getting information from and updating a database. Although SQL is both an ANSI and an ISO standard, many database products support SQL with proprietary extensions to the standard language. Queries take the form of a command language that lets you select, insert, update, find out the location of data, and so forth. There is also a programming interface
Object Oriented Database Management Systems (OODBMS)
An object-oriented database management system (OODBMS) sometimes shortened to ODBMS for object database management system), is a database management system (DBMS) that supports the modeling and creation of data as objects. This includes some kind of support for classes of objects and the inheritance of class properties and methods by subclasses and their objects. There is currently no widely agreed-upon standard for what constitutes an OODBMS, and OODBMS products are considered to be still in their infancy. In the meantime, the object-relational database management system (ORDBMS), the idea that object-oriented database concepts can be superimposed on relational databases, is more commonly encountered in available products. An object-oriented database interface standard is being developed by an industry group, the Object Data Management Group (ODMG). The Object Management Group (OMG) has already standardized an object-oriented data-brokering interface between systems in a network. Postgres is an example of Object Relational Database Management Systems.
Postgres
PostgreSQL is a highly scalable, SQL compliant, open source object-relational database management system. With more than 15 years of development history, it is quickly becoming the de facto database for enterprise level open source solutions.
SAP (System Application Product)
SAP, started in 1972 by five former IBM employees in Mannheim, Germany, states that it is the world's largest inter-enterprise software company and the world's fourth-largest independent software supplier, overall. The original SAP idea was to provide customers with the ability to interact with a common corporate database for a comprehensive range of applications. Gradually, the applications have been assembled and today many corporations, including IBM and Microsoft, are using SAP products to run their own businesses.
SAP applications, built around their latest R/3 system, provide the capability to manage financial, asset, and cost accounting, production operations and materials, personnel, plants, and archived documents. The R/3 system runs on a number of platforms including Windows 2000 and uses the client/server model. The latest version of R/3 includes a comprehensive Internet-enabled package.
SAP has recently recast its product offerings under a comprehensive Web interface, called mySAP.com, and added new e-business applications, including customer relationship management (CRM) and supply chain management (SCM).
In early 2001, SAP, a publicly traded company, had 21,500 employees in over 50 countries, and more than 30,000 installations. SAP is turning its attention to small- and-medium sized businesses. A recent R/3 version was provided for IBM's AS/400 platform.
SAP R/3
R/3 is the comprehensive set of integrated business applications from SAP, the German company that states it is the market and technology leader in business application software. R/3 replaced an earlier system, R/2, which is still in use. R/3 uses the client/server model and provides the ability to store, retrieve, analyze, and process in many ways corporate data for financial analysis, production operation, human resource management, and most other business processes.
A recent release of R/3 makes it possible to get to the R/3 database and applications through Internet access and Web browsers. A sales representative can initiate the workflow for a sales order by filling out an electronic form on a laptop that will be "translated" into input for the R/3 system. Other interfaces such as Lotus Notes can also be used. The Web implementation adheres to the Workflow Client API standard of the Workflow Management Coalition (WfMC).
A more recent version of R/3 adds features designed to speed product delivery by helping to manage the supply chain.
SAP Modules
In the past when people were discussing SAP, the conversation very quickly boiled down to modules, for example:
SAP’s courses were structured along module lines so that you would attend MM 101, 102 and 103. While at the course you would learn many things about MM, but not much about the rest of the SAP system and how MM fits into it.
A conversation with a SAP recruiter might go something like this:
Recruiter … “which modules do you work with?”
Candidate … “well, I have a lot of purchasing process experience”
Recruiter … “yes, but which modules do you work with?”
Candidate … “well, it’s purchasing functionality … so that would be… umm. MM, FI and CO mainly”
Recruiter … “great I have just the job for you”
Candidate … “fantastic, is it purchasing?”
Recruiter … “well it says here that they want an MM, FI and CO person and that’s you, right?”
Not necessarily! A MM, FI, CO role might include Inventory Management (MM), Accounts Receivable (FI) and Profitability Analysis (CO) – none of which a purchasing person is guaranteed to have
Many programmer teams were organized along module lines, so that you would have a FI/CO, an MM and a HR team, for example. Training courses were (therefore) often prepared and delivered along module lines too. The result of this was that solutions were frequently optimized along module lines, and less often well integrated, and as for users, well, they were pretty much trained up in a module and left to get on with it post go-live. Fortunately those days are mostly passed, and more and more programmes (from design to build to training) are being organized along process lines such as:
- Order to Cash (including parts of SD, FI-AR and probably TY as well)
- Purchase to Pay (including MM-Purchasing and FI-AP)
- Record to Report (FI-GL etc)
SAP now are moving away from describing their system as a set of modules, and now are using the term ‘solutions’, which is much better. If you visit SAP’s website you will find that they have structured their Solutions tab as follows:
- Financials
- Human Resources
- Customer Relationship Management
- Supplier Relationship Management
- Product Lifecycle Management
- Supply Chain Management
- Business Intelligence
- The list of various SAP Modules is as follows: -
- FI Financial Accounting – essentially your regulatory ‘books of record’, including
- General ledger
- Book close
- Tax
- Accounts receivable
- Accounts payable
- Consolidation
- Special ledgers
- CO Controlling – basically your internal cost/management accounting, including
- Cost elements
- Cost centers
- Profit centers
- Internal orders
- Activity based costing
- Product costing
- AM Asset Management – track, value and depreciate your assets, including
- Purchase
- Sale
- Depreciation
- Tracking
- PS Project Systems – manage your projects, large and small, including
- Make to order
- Plant shut downs (as a project)
- Third party billing (on the back of a project)
- HR Human Resources – ah yes, people, including
- Employment history
- Payroll
- Training
- Career management
- Succession planning
- PM Plant Maintenance – maintain your equipment (e.g. a machine, an oil rig, an aircraft etc), including
- Labor
- Material
- Down time and outages
- MM Materials Management – underpins the supply chain, including
- Requisitions
- Purchase orders
- Goods receipts
- Accounts payable
- Inventory management
- BOM’s
- Master raw materials, finished goods etc
- QM Quality Management – improve the quality of your goods, including
- Planning
- Execution
- Inspections
- Certificates
- PP Production Planning – manages your production process, including
- Capacity planning
- Master production scheduling
- Material requirements planning
- Shop floor
- SD Sales and Distribution – from order to delivery, including
- RFQ
- Sales orders
- Pricing
- Picking (and other warehouse processes)
- Packing
- Shipping
- CA Cross Application – these lie on top of the individual modules, and include
- WF – workflow
- BW – business information warehouse
- Office – for email
- Workplace
- Industry solutions
- New Dimension products such as CRM, PLM, SRM, APO etc
Network
Network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain sub networks.
The most common topology or general configurations of networks include the bus, star, Token Ring, and mesh topologies. Networks can also be characterized in terms of spatial distance as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs).
Local Area Network (LAN)
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users (for example, in an FDDI network).
Major local area network technologies are:
- Ethernet
- Token Ring
- FDDI (Fiber Distributed Data Interface)
Ethernet
Ethernet is the most widely installed local area network (LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.
Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.
Token Ring
A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second
The token scheme can also be used with bus topology LANs.
FDDI (Fiber Distributed Data Interface)
FDDI is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the Token Ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users. FDDI is frequently used on the backbone for a wide area network (WAN).
An FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbps capacity. If the secondary ring is not needed for backup, it can also carry data, extending capacity to 200 Mbps. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 miles).
FDDI is a product of American National Standards Committee X3-T9 and conforms to the Open Systems Interconnection (OSI) model of functional layering. It can be used to interconnect LANs using other protocols. FDDI-II is a version of FDDI that adds the capability to add circuit-switched service to the network so that voice signals can also be handled. Work is underway to connect FDDI networks to the developing Synchronous Optical Network (SONET).
Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.
Wide Area Network (WAN)
A wide area network (WAN) is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN).
The various types of Network Topologies are as follows: -
Bus Network Topology
A bus network is an arrangement in a local area network (LAN) in which each node (workstation or other device) is connected to a main cable or link called the bus. A bus network is simple and reliable. If one node fails to operate, all the rest can still communicate with each other. For a major disruption to take place, the bus itself must be broken somewhere. Bus networks are easy to expand. Additional nodes can be added anywhere along the bus.
There are several limitations to the bus network topology. The length of the bus is limited by cable loss. A bus network may not work well if the nodes are located at scattered points that do not lie near a common line. In situations like this, a ring network, mesh network, or star network may prove more flexible and more cost effective.
Star Network Topology
A star network is a local area network (LAN) in which all nodes (workstations or other devices) are directly connected to a common central computer. Every workstation is indirectly connected to every other through the central computer. In some star networks, the central computer can also operate as a workstation.
The star network topology works well when workstations are at scattered points. It is easy to add or remove workstations.
If the workstations are reasonably close to the vertices of a convex polygon and the system requirements are modest, the ring network topology may serve the intended purpose at lower cost than the star network topology. If the workstations lie nearly along a straight line, the bus network topology may be best.
In a star network, a cable failure will isolate the workstation that it links to the central computer, but only that workstation will be isolated. All the other workstations will continue to function normally, except that they will not be able to communicate with the isolated workstation. If any workstation goes down, none of the other workstations will be affected. But if the central computer goes down, the entire network will suffer degraded performance or complete failure. If redundancy is required, the mesh network topology may be preferable.
Mesh Network Topology
A mesh network is a local area network (LAN) that employs one of two connection arrangements, full mesh topology or partial mesh topology. In the full mesh topology, each node (workstation or other device) is connected directly to each of the others. In the partial mesh topology, some nodes are connected to all the others, but some of the nodes are connected only to those other nodes with which they exchange the most data.
A mesh network is reliable and offers redundancy. If one node can no longer operate, all the rest can still communicate with each other, directly or through one or more intermediate nodes. Mesh networks work well when the nodes are located at scattered points that do not lie near a common line.
The chief drawback of the mesh topology is expense, because of the large number of cables and connections required. In some scenarios, a ring network or star network may prove more cost effective than a mesh network. If all the nodes lie near a common line, the bus network topology is often the best alternative in terms of cost.
Token Ring Network Topology
A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second
The token scheme can also be used with bus topology LANs.
Network Models
1) Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session. Other models with which it might be contrasted include the client/server model and the master/slave model. In some cases, peer-to-peer communications is implemented by giving each communication node both server and client capabilities. In recent usage, peer-to-peer has come to describe applications in which users can use the Internet to exchange files with each other directly or through a mediating server.
2) Client/server model describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. Although programs within a single computer can use the client/server idea, it is a more important idea in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations. Computer transactions using the client/server model are very common.
The client/server model has become one of the central ideas of network computing. Most business applications being written today use the client/server model. So does the Internet's main program, TCP/IP. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the "monolithic" centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client/server model and become part of network computing.
In the usual client/server model, one server, sometimes called a daemon, is activated and awaits client requests. Typically, multiple client programs share the services of a common server program. Both client programs and server programs are often part of a larger program or application. Relative to the Internet, your Web browser is a client program that requests services (the sending of Web pages or files) from a Web server (which technically is called a Hypertext Transport Protocol or HTTP server) in another computer somewhere on the Internet. Similarly, your computer with TCP/IP installed allows you to make client requests for files from File Transfer Protocol (FTP) servers in other computers on the Internet.
Network Protocols
When data is being transmitted between two or more devices something needs to govern the controls that keep this data intact. A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which hits and bytes are sent across wire) or high-level exchanges between application programs (e.g., the way in which two programs transfer a file across the Internet).
The most widely used protocols are as follows: -
HTTP: -
HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of protocols (the foundation protocols for the Internet).
HTTP concepts include (as the Hypertext part of the name implies) the idea that files can contain references to other files whose selection will elicit additional transfer requests. Any Web server machine contains, in addition to the Web page files it can serve, an HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Internet Protocol address (IP address) indicated by the URL. The HTTP daemon in the destination server machine receives the request and sends back the requested file or files associated with the request. (A Web page often consists of more than one file.)
The latest version of HTTP is HTTP 1.1.
FTP
File Transfer Protocol (FTP), a standard Internet protocol, is the simplest way to exchange files between computers on the Internet. Like the Hypertext Transfer Protocol (HTTP), which transfers displayable Web pages and related files, and the Simple Mail Transfer Protocol (SMTP), which transfers e-mail, FTP is an application protocol that uses the Internet's TCP/IP protocols. FTP is commonly used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet. It's also commonly used to download programs and other files to your computer from other servers.
As a user, you can use FTP with a simple command line interface (for example, from the Windows MS-DOS Prompt window) or with a commercial program that offers a graphical user interface. Your Web browser can also make FTP requests to download programs you select from a Web page. Using FTP, you can also update (delete, rename, move, and copy) files at a server. You need to logon to an FTP server. However, publicly available files are easily accessed using anonymous FTP.
Basic FTP support is usually provided as part of a suite of programs that come with TCP/IP. However, any FTP client program with a graphical user interface usually must be downloaded from the company that makes it.
TCP/IP
TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.
TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.
TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. TCP/IP and the higher-level applications that use it are collectively said to be "stateless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being stateless frees network paths so that everyone can use them continuously. (Note that the TCP layer itself is not stateless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)
SMTP
SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving e-mail. However, since it is limited in its ability to queue messages at the receiving end, it is usually used with one of two other protocols, POP3 or IMAP that let the user save messages in a server mailbox and download them periodically from the server. In other words, users typically use a program that uses SMTP for sending e-mail and either POP3 or IMAP for receiving e-mail. On Unix-based systems, sendmail is the most widely used SMTP server for e-mail. A commercial package, Sendmail, includes a POP3 server. Microsoft Exchange includes an SMTP server and can also be set up to include POP3 support.
PPP
PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server. For example, your Internet server provider may provide you with a PPP connection so that the provider's server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. PPP uses the Internet protocol (IP) (and is designed to handle others). It is sometimes considered a member of the TCP/IP suite of protocols. Relative to the Open Systems Interconnection (OSI) reference model, PPP provides layer 2 (data-link layer) services. Essentially, it packages your computer's TCP/IP packets and forwards them to the server where they can actually be put on the Internet.
Serial Line Internet Protocol (SLIP)
SLIP is a TCP/IP protocol used for communication between two machines that are previously configured for communication with each other. For example, your Internet server provider may provide you with a SLIP connection so that the provider's server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. Your dial-up connection to the server is typically on a slower serial line rather than on the parallel or multiplex lines such as a line of the network you are hooking up to.
A better service is provided by the Point-to-Point Protocol (PPP).
Network Security Terminologies
Access Control
Refers to mechanisms and policies that restrict access to computer resources. An access control list (ACL), for example, specifies what operations different users can perform on specific files and directories
Antivirus
A software program designed to identify and remove a known or potential computer virus
Application Gateway Firewall
Application gateways look at data at the application layer of the protocol stack and serve as proxies for outside users, intercepting packets and forwarding them to the application. Thus, outside users never have a direct connection to anything beyond the firewall. The fact that the firewall looks at this application information means that it can distinguish among such things as Telnet, file transfer protocol (FTP), or Lotus Notes traffic. Because the application gateway understands these protocols, it provides security for each application it supports.
Archiving
an archive is a collection of computer files that have been packaged together for backup, to transport to some other location, for saving away from the computer so that more hard disk storage can be made available, or for some other purpose. An archive can include a simple list of files or files organized under a directory or catalog structure (depending on how a particular program supports archiving).
Authentication
The process of determining the identity of a user that is attempting to access a network. Authentication occurs through challenge/response, time-based code sequences or other techniques
Authorization
The process of determining what types of activities or access is permitted on a network. Usually used in the context of authentication: once you have authenticated a user, they may be authorized to have access to a specific service.
Certificate Authority (CA)
A certificate authority is an authority in a network that issues and manages security credentials and public keys for message encryption and decryption. As part of a public key infrastructure (PKI), a CA checks with a registration authority (RA) to verify information provided by the requestor of a digital certificate. If the RA verifies the requestor's information, the CA can then issue a certificate.
Challenge-Response
A common authentication technique whereby an individual is prompted (the challenge) to provide some private information (the response). Most security systems that rely on smart cards are based on challenge-response. A user is given a code (the challenge), which he or she enters into the smart card. The smart card then displays a new code (the response) that the user can present to log in.
CHAP (Challenge-Handshake Authentication Protocol)
An authentication technique where after a link is established, a server sends a challenge to the requestor. The requestor responds with a value obtained by using a one-way hash function. The server checks the response by comparing it its own calculation of the expected hash value. If the values match, the authentication is acknowledged otherwise the connection is usually terminated.
Cryptography
A branch of complex mathematics and engineering devoted to protecting information from unwanted access. In the context of computer networking, cryptography consists of encryption, authentication, and authorization
DES (Data Encryption Standard)
A widely-used method of data encryption using a private (secret) key that was judged so difficult to break by the U.S. government that it was restricted for exportation to other countries. There are 72,000,000,000,000,000 (72 quadrillion) or more possible encryption keys that can be used. For each given message, the key is chosen at random from among this enormous number of keys. Like other private key cryptographic methods, both the sender and the receiver must know and use the same private key
DHCP (Dynamic Host Configuration Protocol)
DHCP enables individual computers on an IP network to extract their configurations from a server (the 'DHCP server') or servers, in particular, servers that have no exact information about the individual computers until they request the information. The overall purpose of this is to reduce the work necessary to administer a large IP network. The most significant piece of information distributed in this manner is the IP address.
Digital Certificate
A digital certificate is an electronic "credit card" that establishes your credentials when doing business or other transactions on the Web. It is issued by a certification authority (CA). It contains your name, a serial number, expiration dates, a copy of the certificate holder's public key (used for encrypting and decrypting messages and digital signatures), and the digital signature of the certificate-issuing authority so that a recipient can verify that the certificate is real.
Digital Signature
A digital signature is an electronic rather than a written signature that can be used by someone to authenticate the identity of the sender of a message or of the signer of a document. It can also be used to ensure that the original content of the message or document that has been conveyed is unchanged. Additional benefits to the use of a digital signature are that it is easily transportable, cannot be easily repudiated, cannot be imitated by someone else, and can be automatically time-stamped.
DMZ (de-militarized zone)
a network added between a protected network and an external network in order to provide an additional layer of security. Sometimes called a perimeter network.
DNS (Domain Name System)
The Internet protocol for mapping host names, domain names and aliases to IP addresses
Encryption
Scrambling data in such a way that it can only be unscrambled through the application of the correct cryptographic key.
Filter
A filter is a program or section of code that is designed to examine each input or output request for certain qualifying criteria and then process or forward it accordingly.
Firewall
A firewall is a program that protects the resources of one network from users from other networks. Typically, an enterprise with an intranet that allows its workers access to the wider Internet will want a firewall to prevent outsiders from accessing its own private data resources.
Gateway
A gateway is a network point that acts as an entrance to another network. In a company network, a proxy server acts as a gateway between the internal network and the Internet. A gateway may also be any machine or service that passes packets from one network to another network in their trip across the Internet.
Hubs
In describing network topologies, a hub topology consists of a backbone (main circuit) to which a number of outgoing lines can be attached ("dropped"), each providing one or more connection port for device to attach to. For Internet users not connected to a local area network, this is the general topology used by your access provider. Other common network topologies are the bus network and the ring network. (Either of these could possibly feed into a hub network, using a bridge.)
As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a local area network (for example, an Ethernet or a Token Ring), and a connection to a line.
Internet Key Exchange (IKE)
A hybrid protocol whose purpose is to negotiate, and provide authenticated keying material for, security associations in a protected manner. Processes, which implement this protocol, can be used for negotiating virtual private networks (VPNs) and also for providing a remote user from a remote site (whose IP address need not be known beforehand) access to a secure host or network.
IPSec (Internet Protocol Security)
A developing standard for security at the network or packet processing layer of network communication. IPSec provides two choices of security service: Authentication Header (AH), which essentially allows authentication of the sender of data, and Encapsulating Security Payload (ESP), which supports both authentication of the sender and encryption of data as well.
Key
In cryptography, a key is a variable value that is applied using an algorithm to a string or block of unencrypted text to produce encrypted text. The length of the key generally determines how difficult it will be to decrypt the text in a given message.
Public Key Infrastructure (PKI)
PKI (public key infrastructure) enables users of a basically insecure public network such as the Internet to securely and privately exchange data and money through the use of a public and a private cryptographic key pair that is obtained and shared through a trusted authority. The public key infrastructure provides for a digital certificate that can identify an individual or an organization and directory services that can store and, when necessary, revoke the certificates.
Network Information System (NIS)
NIS (Network Information System) is a network naming and administration system for smaller networks that was developed by Sun Microsystems. NIS+ is a later version that provides additional security and other facilities. Using NIS, each host client or server computer in the system has knowledge about the entire system. A user at any host can get access to files or applications on any host in the network with a single user identification and password. NIS is similar to the Internet's domain name system (DNS) but somewhat simpler and designed for a smaller network. It's intended for use on local area networks.
NIS uses the client/server model and the Remote Procedure Call (RPC) interface for communication between hosts. NIS consists of a server, a library of client programs, and some administrative tools. NIS is often used with the Network File System (NFS). NIS is a Unix-based program.
Public Key Cryptography
Asymmetric or public key cryptography is based on the concept of a key pair. Each half of the pair (one key) can encrypt information so that only the other half (the other key) can decrypt it. Only the designated owner knows one part of the key pair, the private key, the other part, the public key, is published widely but is still associated with the owner.
The public key infrastructure assumes the use of public key cryptography, which is the most common method on the Internet for authenticating a message sender or encrypting a message. Traditional cryptography has usually involved the creation and sharing of a secret key for the encryption and decryption of messages. This secret or private key system has the significant flaw that if the key is discovered or intercepted by someone else, messages can easily be decrypted. For this reason, public key cryptography and the public key infrastructure is the preferred approach on the Internet
RSA (Rivest-Shamir-Adleman)
One of the fundamental encryption algorithms or series of mathematical actions developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman. The RSA algorithm is the most commonly used encryption and authentication algorithm and is included as part of the Web browsers from Netscape and Microsoft.
Secure Hash Algorithm-1 (SHA-1)
A one-way cryptographic function, which takes a message, produces a 160-bit message digest. A message digest is a value generated for a message or document that is unique to that message, and is sometimes referred to as a "fingerprint" of that message or data. Once a message digest is computed, any subsequent change to the original data will, with a very high probability, cause a change in the message digest, and the signature will fail to verify. This process is used to compress large data strings to a 20-byte length, which is used in a cryptographic process. The reduced data length relieves computational requirements for data encryption.
VPN (Virtual Private Networking)
A VPN is a technology that overlays communications networks with a management and security layer. Though VPN technology, network managers can set up secure relationships while still enjoying the low cost of a public network such as the Internet.
Routers
A router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any gateway (where one network meets another), including each point-of-presence on the Internet. A router is often included as part of a network switch.
Switches
A digital switch is a device that handles digital signals generated at or passed through a telephone company central office and forwards them across the company's backbone network. It receives the digital signals from the office's channel banks that have been converted from users' analog signals and switches them with other incoming signals out to the wide area network.
BackUp Systems
ArcServe
BrightStor ARCserve Backup r11.1 delivers leading backup and restore protection for all classes of Windows, NetWare, Linux and UNIX servers, as well as Windows, Mac OS X, Linux, UNIX, AS/400 and VMS client environments. It’s easy to use, reliable and scalable, and delivers best-in-class functionality for DAS, NAS and SAN environments, as well as enhanced database and messaging functionality
BMC Patrol
PATROL is a performance and availability monitoring solution that enables you to improve service to your customers while driving down operational costs. You can quickly and cost-effectively integrate PATROL into your management environment. The solution provides QoS monitoring, notification and reporting across customers' servers, networks and application infrastructures. Self-provisioning, ease of use and out-of-the-box capabilities make PATROL Express easy to implement and inexpensive to operate.
Veritas
VERITAS Backup Exec™ 10 for Windows Servers is the Gold Standard in Windows data protection providing comprehensive, cost-effective, and certified backup and recovery - including the fastest disk-based recovery. An intuitive, web-based user interface simplifies installation and management of backup and remote servers with easy-to-use wizards.
Legato
Legato Solutions help organizations solve their data protection, high availability and email management challenges with award-winning backup software.
Tivoli Systems is an IBM-owned company that develops software that allows a business to manage its computing environment. In a large organization, keeping track of and upgrading computer equipment and various levels of operating systems and applications is a formidable task.
e-business infrastructure management
- E-marketplace solutions
- Industry-specific solutions
- Service provider capabilities
- Availability and application management
- Network management
- Operations management
- OS/390 management
Pervasive management (management of mobile devices and point-of-sale terminals)
Storage and storage area network (SAN) management
- Security management
- Service management
- Web management
Cisco Certifications
Cisco Certified Network Professional (CCNP)
Cisco Certified Network Professional (CCNP) is an intermediate-level certification in the Cisco certified professional program. This certification is aimed at full-time network or system administrators, or those who work with local and/or wide-area network (LAN/WAN) infrastructure.
Cisco Certified Network Associate (CCNA)
Cisco Certified Network Associate (CCNA) is an entry-level certification for the Cisco certified professional program. The certification is geared towards junior network administrators.
Cisco Certified Internetwork Expert (CCIE)
Cisco Certified Internetwork Expert (CCIE) is what Cisco describes as its "premium networking certification." The CCIE is widely regarded as having one of the toughest, most demanding exams. It includes both a written exam and a daylong lab exam. This certification is aimed at senior level networking professionals who design, build, implement, maintain, or troubleshoot complex enterprise networking infrastructures. CCIE recipients can specialize in routing and switching, communications and services, security, or voice systems and technologies.
Operating System?
An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
An operating system performs these services for applications:
In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.
It manages the sharing of internal memory among multiple applications.
It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.
It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.
All major computer platforms (hardware and software) require and sometimes include an operating system. Linux, Windows 2000, VMS, OS/400, AIX, and z/OS are all examples of operating systems.
The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure those different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating Systems are classified according to the following parameters: -
- Multi-user: Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
- Multiprocessing: Supports running a program on more than one CPU.
- Multitasking: Allows more than one program to run concurrently.
- Multithreading: Allows different parts of a single program to run concurrently.
- Real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, are not real-time
Types of OS:
DOS
DOS (Disk Operating System) was the first widely installed operating system for personal computers. (Earlier, the same name had been used for an IBM operating system for a line of business computers.)
The first personal computer version of DOS, called PC-DOS, was developed for IBM by Bill Gates and his new Microsoft Corporation. He retained the rights to market a Microsoft version, called MS-DOS. PC-DOS and MS-DOS are almost identical and most users have referred to either of them as just "DOS." DOS was (and still is) a non-graphical line-oriented command- or menu-driven operating system, with a relatively simple interface but not overly "friendly" user interface. Its prompt to enter a command looks like this: C:>
The first Microsoft Windows operating system was really an application that ran on top of the MS-DOS operating system. Today, Windows operating systems continue to support DOS (or a DOS-like user interface) for special purposes by emulating the operating system.
In the 1970s before the personal computer was invented, IBM had a different and unrelated DOS (Disk Operating System) that ran on smaller business computers. It was replaced by IBM's VSE operating system.
Unix (often spelled "UNIX," especially as an official trademark) is an operating system that originated at Bell Labs in 1969 as an interactive time-sharing system. Ken Thompson and Dennis Ritchie are considered the inventors of Unix. The name (pronounced YEW-nihks) was a pun based on an earlier system, Multics. In 1974, Unix became the first operating system written in the C language. Unix has evolved as a kind of large freeware product, with many extensions and new ideas provided in a variety of versions of Unix by different companies, universities, and individuals.
Partly because it was not a proprietary operating system owned by any one of the leading computer companies and partly because it is written in a standard language and embraced many popular ideas, Unix became the first open or standard operating system that could be improved or enhanced by anyone. A composite of the C language and shell (user command) interfaces from different versions of Unix were standardized under the auspices of the IEEE as the Portable Operating System Interface (POSIX). In turn, the POSIX interfaces were specified in the X/Open Programming Guide 4.2. These interfaces are also known as the "Single UNIX Specification" and, in the most recent version, "UNIX 03"). The The Open Group, an industry standards organization, which certifies and brands Unix implementations, now owns the trademarked “UNIX”.
Unix operating systems are used in widely sold workstation products from Sun Microsystems, Silicon Graphics, IBM, and a number of other companies. The Unix environment and the client/server program model were important elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. R a Unix derivative available in both "free software" and commercial versions, is increasing in popularity as an alternative to proprietary operating systems
Windows OS
Windows is a personal computer operating system from Microsoft that, together with some commonly used business applications such as Microsoft Word and Excel, has become a de facto "standard" for individual users in most corporations as well as in most homes.
The original 1985 version of Windows introduced to home and business PC users many of the graphical user interface (GUI) ideas that were developed at an experimental lab at Xerox and introduced commercially by Apple's Lisa and Macintosh computers. Some of the well-known versions of Windows have included:
- Windows 95
- Windows 98
- Windows NT
- Windows 2000
- Windows XP
With the advent of the Internet, Microsoft has repositioned Windows as a kind of "window to the world," and its efforts to take the lead in Web browsers have made Internet Explorer the most popular browser. Microsoft's . NET initiative represents an attempt to become industry-dominant in furnishing products and services that facilitate the use of remote application services on the Web.
Win95 OS
A major release of the Microsoft Windows operating system released in 1995. Windows 95 represents a significant advance over its precursor, Windows 3.1. In addition to sporting a new user interface, Windows 95 also includes a number of important internal improvements. Perhaps most important, it supports 32-bit applications, which means that applications written specifically for this operating system should run much faster. And although Windows 95 can run older Windows and DOS applications, it has essentially removed DOS as the underlying platform. This has meant removal of many of the old DOS limitations, such as 640K of main memory and 8-character filenames.
Win98 OS
Originally it was called
Windows 98 offers support for a number of new technologies, including FAT32, AGP, MMX, USB, DVD, and ACPI. Its most visible feature, though, is the Active Desktop, which integrates the Web browser (Internet Explorer) with the operating system. From the user's point of view, there is no difference between accessing a document residing locally on the user's hard disk or on a Web server halfway around the world
Windows NT OS
Windows NT is a Microsoft Windows personal computer operating system designed for users and businesses needing advanced capability. NT's technology is the base for the Microsoft successor operating system, Windows 2000. Windows NT (which may originally have stood for "New Technology," although Microsoft doesn't say) is actually two products: Microsoft NT Workstation and Microsoft NT Server. The Workstation is designed for users, especially business users, who need faster performance and a system a little more fail-safe than Windows 95 and Windows 98. The Server is designed for business machines that need to provide services for network-attached computers. The Server is required, together with an Internet server such as Microsoft's Internet Information Server (IIS), for a Windows system that plans to serve Web pages.
Windows NT Workstation: Microsoft says that 32-bit applications run 20% faster on this system than on Windows 95 (assuming both have 32 megabytes of RAM). Since older 16-bit applications run in a separate address space, one can crash without crashing other applications or the operating system. Security and management features not available on Windows 95 are provided. The Workstation has the same desktop user interface as Windows 95.
Windows NT Server
The NT Server is probably the second most installed network server operating system after Novell's NetWare operating system. Microsoft claims that its NT servers are beginning to replace both NetWare and the various Unix-based systems such as those of Sun Microsystems and Hewlett-Packard. NT Server 5.0. essentially became what was renamed Windows 2000. Notable features of the Windows 2000 products are:
A fully customizable administrative console that can be based on tasks rather than files, applications, or users.
A new file directory approach called Active Directory that lets the administrator and other users view every file and application in the network from a single point-of-view.
Dynamic Domain Name Server (DNS), which replicates changes in the network using the Active Directory Services, the Dynamic Host Configuration Protocol (DHCP), and the Windows Internet Naming Service (WINS) whenever a client is reconfigured.
The ability to create, extend, or mirror a disk volume without having to shut down the system and to back up data to a variety of magnetic and optical storage media.
A Distributed File System (DFS) that lets users see a distributed set of files in a single file structure across departments, divisions, or an entire enterprise.
Close integration with and support for Microsoft's Message Queue Server, Microsoft Transaction Server, and Internet Information Server (IIS).
WinXP
An operating system introduced in 2001 from Microsoft's Windows family of operating systems, the previous version of Windows being Windows Me. Microsoft called the release its most important product since Windows 95. Along with a redesigned look and feel to the user interface, the new operating system is built on the Windows 2000 kernel, giving the user a more stable and reliable environment than previous versions of Windows. Windows XP comes in two versions, Home and Professional. The company has focused on mobility for both editions, including plug and play features for connecting to wireless networks. The operating system also utilizes the 802.11x wireless security standard.
The "XP" in Windows XP stands for "eXPerience."
Linux
Linux (often pronounced LIH-nuhks with a short "i") is an Unix-like operating system that was designed to provide personal computer users a free or very low-cost operating system comparable to traditional and usually more expensive Unix systems. Linux has a reputation as a very efficient and fast-performing system. Linux's kernel (the central part of the operating system) was developed by Linus Torvalds at the
Linux is a remarkably complete operating system, including a graphical user interface, an X Window System, TCP/IP, the Emacs editor, and other components usually found in a comprehensive Unix system. Although various creators of Linux’s components hold copyrights, Linux is distributed using the Free Software Foundation's copy left stipulations that mean any modified version that is redistributed must in turn be freely available.
Unlike Windows and other proprietary systems, Linux is publicly open and extendible by contributors. Because it conforms to the Portable Operating System Interface standard user and programming interfaces, developers can write programs that can be ported to other operating systems. Linux comes in versions for all the major microprocessor platforms including the Intel, PowerPC, Sparc, and Alpha platforms. It's also available on IBM's S/390. Linux is distributed commercially by a number of companies. A magazine, Linux Journal, is published as well as a number of books and pocket references.
Linux is sometimes suggested as a possible publicly developed alternative to the desktop predominance of Microsoft Windows. Although Linux is popular among users already familiar with Unix, it remains far behind Windows in numbers of users. However, its use in the business enterprise is growing.
Linux is a contraction for Linus' Unix; the short i sound preferred by most (including Torvalds) derives from the Swedish pronunciation of Linus
Mac OS
Mac OS is the computer operating system for Apple Computer's Macintosh line of personal computers and workstations. A popular feature of its latest version, Mac OS X, is a desktop interface with some 3-D appearance characteristics. OS X has a modular design intended to make it easier to add new features to the operating system in the future. It runs Unix applications as well as older Mac applications.
Mac OS comes with Apple Computer's iMac and Power Macintosh line of computers.
Palm OS
Palm OS is the computer operating system that provides a software platform for the Palm series of handheld personal digital assistants (PDAs) made by Palm Inc. According to Palm, Palm OS was designed from the beginning to fit into a palm-size device of a specific size and with a specific display size. Microsoft's Windows CE and Symbian's EPOC (originated by Psion) are also operating systems for handheld devices, but are designed to serve a broader range of devices.
Palm OS uses multitasking, but only one task is for applications. The user uses one application at a time; one application program must finish before the next can be selected. This constraint allows the operating system to devote full attention to the application that is open. The space needed by the system for any application that is running is kept in dynamic, reusable random access memory (RAM). The application and its related database are kept in what is called permanent storage, but here the permanent storage is RAM (rather than a hard disk) that cannot be reused as the dynamic RAM can. Palm OS divides an application into run able code and different types of data elements, such as user interface elements and icons. The data elements can be easily changed without necessarily having to rewrite code.
Palm OS comes with these applications built-in: Dates, Address Book, To Do Lis, Memo Pad, Calculator, and Password Protection. New applications can be written and added using several facilities that accelerate development.
Palm supports Metrowerks' CodeWarrior as the official software development kit (SDK), using a Macintosh or Windows environment. Unix platform users can use a kit called GCC, which is available through the Free Software Foundation. Programmers can use C, C++, assembler, or scripting. The Palm user interface is emulated within a window in the desktop environment, encouraging rapid application development. Simpler applications can be developed using Palm's forms interface.
Palm OS comes with communication interfaces to infrared transmission devices, TCP/IP (for Web connection through wireless or wireline devices), and, optionally, barcode recognition scanners.
Z OS
Z/OS is the computer operating system for IBM's zSeries 900 (z900) line of large (mainframe) servers. Z/OS is a renamed and upgraded version of OS/390, which in turn evolved from the MVS operating system. IBM's renamed servers and operating systems reflect a strategy to realign its products more closely with the Internet and its own e-business initiatives.
Z/OS is described as an extremely scalable and secure high-performance operating system based on the 64-bit z/Architecture. Like its predecessor, OS/390, z/OS lays claim to being highly reliable for running mission-critical applications. The operating system supports Web- and Java-based applications.
Novell
NDS (Novell Directory Services) is a popular software product for managing access to computer resources and keeping track of the users of a network, such as a company's intranet, from a single point of administration. Using NDS, a network administrator can set up and control a database of users and manage them using a directory with an easy-to-use graphical user interface (GUI). Users of computers at remote locations can be added, updated, and managed centrally. Applications can be distributed electronically and maintained centrally.
NDS can be installed to run under Windows NT, Sun Microsystems’s Solaris, and IBM's OS/390 as well as under Novell's own NetWare so that it can be used to control a multi-platform network. NDS is generally considered an industry benchmark against which other products, such as Microsoft's Active Directory, must compete.
Citrix Metaframe Server
MetaFrame is the name for a thin client/server software application from Citrix that is used to provide Microsoft's Windows Terminal Server product (WTS) with additional server and client functionality by allowing any client, no matter what operating system (OS) they are using, to connect to a Windows Terminal Server and run a Windows application through their browser. MetaFrame is useful for its ability to "load balance" by automatically directing a client to the server with the lightest load in a server farm, and its ability to allow publishing and application management from a single server in that farm. MetaFrame also features a secure encryption option through a distributed Windows presentation protocol developed by Citrix, called
Types of Application
Applications can be classified on the basis of platform, which are as follows: -
Desktop Applications
A desktop application system allows you to use different typefaces, specify various margins and justifications, and embed illustrations and graphs directly into the text. The most powerful desktop applications enable you to create illustrations, while less powerful systems let you insert illustrations created by other programs.
As word-processing programs become more and more powerful, the line separating such programs from desktop publishing systems is becoming blurred. In general, though, desktop publishing applications give you more control over typographical characteristics, such as kerning, and provide more support for full-color output.
A particularly important feature of desktop applications is that they enable you to see on the display screen exactly how the document will appear when printed. Systems that support this feature are called WYSIWYGs (what you see is what you get).
Web Applications
A Web application is a dynamic extension of a Web server. There are two types of Web applications, which are mentioned as follows: -
Presentation-oriented
A presentation-oriented Web application generates dynamic Web pages containing various types of markup language (HTML, XML, and so on) in response to requests.
Service-oriented
A service-oriented Web application implements the endpoint of a fine-grained Web service. Service-oriented Web applications are often invoked by presentation-oriented applications.
In the Java 2 Platform, Web components provide the dynamic extension capabilities for a Web server. Web components are either Java Servlets or JSP pages. Servlets are Java programming language classes that dynamically process requests and construct responses. JSP pages are text-based documents that execute as servlets but allow a more natural approach to creating static content. Although servlets and JSP pages can be used interchangeably, each has its own strengths. Servlets are best suited to service-oriented Web applications and managing the control functions of a presentation-oriented application, such as dispatching requests and handling nontextual data. JSP pages are more appropriate for generating text-based markup such as HTML, SVG, WML, and XML.
Web components are supported by the services of a runtime platform called a Web container. In the Java Web Services Developer Pack (Java WSDP) Web components run in the Tomcat Web container. The Web container provides services such as request dispatching, security, concurrency, and life cycle management. It also gives Web components access to APIs such as naming, transactions, and e-mail.
Embedded Applications
An embedded system is some combination of computer hardware and software, either fixed in capability or programmable, which is specifically designed for a particular kind of application device. Industrial machines, automobiles, medical equipment, cameras, household appliances, airplanes, vending machines, and toys (as well as the more obvious cellular phone and PDA) are among the myriad possible hosts of an embedded system. Embedded systems that are programmable are provided with a programming interface, and embedded systems programming is a specialized occupation.
Certain operating systems or language platforms are tailored for the embedded market, such as EmbeddedJava and Windows XP Embedded. However, some low-end consumer products use very inexpensive microprocessors and limited storage, with the application and operating system both part of a single program. The program is written permanently into the system's memory in this case, rather than being loaded into RAM (random access memory), as programs on a personal computer are.
EAI (enterprise application integration) is a business computing term for the plans, methods, and tools aimed at modernizing, consolidating, and coordinating the computer applications in an enterprise. Typically, an enterprise has existing legacy applications and databases and wants to continue to use them while adding or migrating to a new set of applications that exploit the Internet, e-commerce, extranet, and other new technologies. EAI may involve developing a new total view of an enterprise's business and its applications, seeing how existing applications fit into the new view, and then devising ways to efficiently reuse what already exists while adding new applications and data.
EAI encompasses methodologies such as object-oriented programming, distributed, cross-platform program communication using message brokers with Common Object Request Broker Architecture and COM+, the modification of enterprise resource planning (ERP) to fit new objectives, enterprise-wide content and data distribution using common databases and data standards implemented with the Extensible Markup Language (XML), middleware, message queuing, and other approaches.
System Applications
A program or group of programs designed for end users. Software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources.
In contrast, applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.
Wireless application service provider (WASP) is part of a growing industry sector resulting from the convergence of two trends: wireless communications and the outsourcing of services. A WASP performs the same service for wireless clients as a regular application service provider (ASP) does for wired clients: it provides Web-based access to applications and services that would otherwise have to be stored locally. The main difference with WASP is that it enables customers to access the service from a variety of wireless devices, such as a smartphone or personal digital assistant (PDA).
Although the business world is increasingly mobile, many corporations are resisting the idea of wireless communication, because of concerns about set-up and maintenance costs and the need for in-house expertise. WASPs offer businesses the advantages of wireless service with less expense and fewer risks. Because mobile applications are subscribed to, rather than purchased, up-front costs are lower; because the WASP provides support, staffing and training costs are lower.
WASP services may include:
- Constant system monitoring
- Diagnostics and resolution
- User support
- Text formatting for various devices
- Problem detection and reporting
Server
Server is a computer on a network that is dedicated to a particular purpose and which stores all information and performs the critical functions for that purpose. For example, a Web server would store all files related to a Web site and perform all work necessary for hosting the Web site. Most congressional offices have at least one server that is dedicated as both a network server and a file server. This means that, in it's network server role, the computer is responsible for holding the files and managing the processes that enable everyone in the office to access and use the network. In it's file server role, it holds the central computer files and the CMS database.
As the name implies, a server serves information to computers that connect to it. When users connect to a server, they can access programs, files, and other information from the server Common servers is Web servers, mail servers, and LAN servers. A single computer can have several different server programs running on it.
Application Server
An application server is a server program in a computer in a distributed network that provides the business logic for an application program. The application server is frequently viewed as part of a three-tier application, consisting of a graphical user interface (GUI) server, an application (business logic) server, and a database and transaction server. More descriptively, it can be viewed as dividing an application into:
A first-tier, front-end, Web browser-based graphical user interface, usually at a personal computer or workstation
A middle-tier business logic application or set of applications, possibly on a local area network or intranet server
A third-tier, back-end, database and transaction server, sometimes on a mainframe or large server
Older, legacy application databases and transaction management applications are part of the back end or third tier. The application server is the middleman between browser-based front-ends and back-end databases and legacy systems.
In many usages, the application server combines or works with a Web (Hypertext Transfer Protocol) server and is called a Web application server. The Web browser supports an easy-to-create HTML-based front-end for the user. The Web server provides several different ways to forward a request to an application server and to forward back a modified or new Web page to the user. These approaches include the Common Gateway Interface (CGI), FastCGI, Microsoft's Active Server Page, and the Java Server Page. In some cases, the Web application servers also support request "brokering" interfaces such as CORBA Internet Inter-ORB Protocol (IIOP).
Web Server
A Web server is a program that, using the client/server model and the World Wide Web's Hypertext Transfer Protocol (HTTP), serves the files that form Web pages to Web users (whose computers contain HTTP clients that forward their requests). Every computer on the Internet that contains a Web site must have a Web server program. Two leading Web servers are Apache, the most widely installed Web server, and Microsoft's Internet Information Server (IIS). Other Web servers include Novell's Web Server for users of its NetWare operating system and IBM's family of Lotus Domino servers, primarily for IBM's OS/390 and AS/400 customers.
Web servers often come as part of a larger package of Internet- and intranet-related programs for serving e-mail, downloading requests for File Transfer Protocol (FTP) files, and building and publishing Web pages. Considerations in choosing a Web server include how well it works with the operating system and other servers, its ability to handle server-side programming, security characteristics, and publishing, search engine, and site building tools that may come with it.
FTP Server
A computer responsible for serving any kind of files, via the FTP protocol to ftp clients, which can also web browsers;
A software program that implements the FTP protocol and is working as a daemon serving any kind of files.
Proxy Server
A proxy server is a server that acts as an intermediary between a workstation user and the Internet so that the enterprise can ensure security, administrative control, and caching service. A proxy server is associated with or part of a gateway server that separates the enterprise network from the outside network and a firewall server that protects the enterprise network from outside intrusion.
A proxy server receives a request for an Internet service (such as a Web page request) from a user. If it passes filtering requirements, the proxy server, assuming it is also a cache server, looks in its local cache of previously downloaded Web pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.
To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server. (The proxy is not quite invisible; its IP address has to be specified as a configuration option to the browser or other protocol program.)
An advantage of a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy's cache, which will improve user response time. In fact, there are special servers called cache servers. A proxy can also do logging.
The functions of proxy, firewall, and caching can be in separate server programs or combined in a single package. Different server programs can be in different computers. For example, a proxy server may in the same machine with a firewall server or it may be on a separate server and forward requests through the firewall.
File Server
In the client/server model, a file server is a computer responsible for the central storage and management of data files so that other computers on the same network can access the files. A file server allows users to share information over a network without having to physically transfer files by floppy diskette or some other external storage device. Any computer can be configured to be a host and act as a file server. In its simplest form, a file server may be an ordinary PC that handles requests for files and sends them over the network. In a more sophisticated network, a file server might be a dedicated network-attached storage (NAS) device that also serves as a remote hard disk drive for other computers, allowing anyone on the network to store files on it as if to their own hard drive.
Internet Information Server (IIS)
IIS (Internet Information Server) is a group of Internet servers (including a Web or Hypertext Transfer Protocol server and a File Transfer Protocol server) with additional capabilities for Microsoft's Windows NT and Windows 2000 Server operating systems. IIS is Microsoft's entry to compete in the Internet server market that is also addressed by Apache, Sun Microsystems, O'Reilly, and others. With IIS, Microsoft includes a set of programs for building and administering Web sites, a search engine, and support for writing Web-based applications that access databases. Microsoft points out that IIS is tightly integrated with the Windows NT and 2000 Servers in a number of ways, resulting in faster Web page serving.
A typical company that buys IIS can create pages for Web sites using Microsoft's Front Page product (with its WYSIWYG user interface). Web developers can use Microsoft's Active Server Page (ASP) technology, which means that applications - including ActiveX controls - can be imbedded in Web pages that modify the content sent back to users. Developers can also write programs that filter requests and get the correct Web pages for different users by using Microsoft's Internet Server Application Program Interface (ISAPI) interface. ASPs and ISAPI programs run more efficiently than common gateway interface (CGI) and server-side include (SSI) programs, two current technologies. (However, there are comparable interfaces on other platforms.)
Microsoft includes special capabilities for server administrators designed to appeal to Internet service providers (ISPs). It includes a single window (or "console") from which all services and users can be administered. It's designed to be easy to add components as snap-ins that you didn't initially install. Individual customers can customize the administrative windows for access. Microsoft has been criticized for IIS's susceptibility to computer virus attacks such as Code Red and Nimda.
Microsoft Internet Security And Acceleration Server (MS-ISA)
Microsoft's ISA Server (Internet Security and Acceleration Server) is the successor to Microsoft's Proxy Server 2.0 (see proxy server) and is part of Microsoft's .NET support. ISA Server provides the two basic services of an enterprise firewall and a Web proxy/cache server. ISA Server's firewall screens all packet-level, circuit-level, and application-level traffic. The Web cache stores and serves all regularly accessed Web content in order to reduce network traffic and provide faster access to frequently accessed Web pages. ISA Server also schedules downloads of Web page updates for non-peak times.
ISA Server allows administrators to create policies for regulating usage based on user, group, application, destination, schedule, and content type criteria. ISA Server is designed to work with Windows 2000 and later operating systems and to take advantage of Windows' Kerberos security. ISA Server includes a software development kit (SDK).
SMS Server
SMS Server is an efficient tool that makes sending and receiving SMS messages from a computer easy. It uses a GSM phone connected to the PC with a phone-to-pc data cable. The software can be used as a stand-alone SMS communicator or can be attached to other systems to accomplish automatic messaging.
RIS Server
Remote Installation Service (RIS) is a feature included in Microsoft's Windows 2000 server that allows network administrators to install the Windows 2000 Professional operating system and its upgrades to any number of client computers at one time from a centralized location. If the client computer is connected to the server through a local area network (LAN), the computer's hardware will find the RIS server and request a copy of the operating system. The network administrator can use the RISrep imaging option to copy several versions, or images, of a company's desktop configuration to the server so that if a request is made, the server can issue an "image" for a particular computer or user. Microsoft promotes the use of RIS as a way to configure new computers right out of the box and to restore the operating system on a computer that has failed.
Apache Server
Apache is a freely available Web server that is distributed under an "open source" license. Version 2.0 runs on most Unix-based operating systems (such as Linux, Solaris, Digital UNIX, and AIX), on other UNIX/POSIX-derived systems (such as Rhapsody, BeOS, and BS2000/OSD), on AmigaOS, and on Windows 2000.
Technologies
Java
Java is a programming language expressly designed for use in the distributed environment of the Internet. It was designed to have the "look and feel" of the C++ language, but it is simpler to use than C++ and enforces an object-oriented programming model. Java can be used to create complete applications that may run on a single computer or be distributed among servers and clients in a network. It can also be used to build a small application module or applet for use as part of a Web page. Applets make it possible for a Web page user to interact with the page.
The major characteristics of Java are:
The programs you create are portable in a network.
Your source program is compiled into what Java calls byte code, which can be run anywhere in a network on a server or client that has a Java virtual machine.
The Java virtual machine interprets the byte code into code that will run on the real computer hardware.
This means that individual computer platform differences such as instruction lengths can be recognized and accommodated locally just as the program is being executed.
Platform-specific versions of your program are no longer needed.
The code is robust, here meaning that, unlike programs written in C++ and perhaps some other languages, the Java objects can contain no references to data external to themselves or other known objects.
This ensures that an instruction cannot contain the address of data storage in another application or in the operating system itself, either of which would cause the program and perhaps the operating system itself to terminate or "crash."
The Java virtual machine makes a number of checks on each object to ensure integrity.
Java is object-oriented, which means that, among other characteristics, an object can take advantage of being part of a class of objects and inherit code that is common to the class. Objects are thought of as "nouns" that a user might relate to rather than the traditional procedural "verbs." A method can be thought of as one of the object's capabilities or behaviors.
In addition to being executed at the client rather than the server, a Java applet has other characteristics designed to make it run fast.
Relative to C++, Java is easier to learn. (However, it is not a language you'll pick up in an evening!)
Java was introduced by Sun Microsystems in 1995 and instantly created a new sense of the interactive possibilities of the Web. Both of the major Web browsers include a Java virtual machine. Almost all major operating system developers (IBM, Microsoft, and others) have added Java compilers as part of their product offerings.
The Java virtual machine includes an optional just-in-time compiler that dynamically compiles byte code into executable code as an alternative to interpreting one byte code instruction at a time. In many cases, the dynamic JIT compilation is faster than the virtual machine interpretation.
JavaScript should not be confused with Java. JavaScript, which originated at Netscape, is interpreted at a higher level, is easier to learn than Java, but lacks some of the portability of Java and the speed of byte code. Because Java applets will run on almost any operating system without requiring recompilation and because Java has no operating system-unique extensions or variations, Java is generally regarded as the most strategic language in which to develop applications for the Web. (However, JavaScript can be useful for very small applications that run on the Web client or server.)
JavaScript
JavaScript is an interpreted programming or script language from Netscape. It is somewhat similar in capability to Microsoft's Visual Basic, Sun's Tcl, the UNIX-derived Perl, and IBM's Rexx. In general, script languages are easier and faster to code in than the more structured and compiled languages such as C and C++. Script languages generally take longer to process than compiled languages, but are very useful for shorter programs.
JavaScript is used in Web site development to do such things as:
- Automatically change a formatted date on a Web page
- Cause a linked-to page to appear in a popup window
- Cause text or a graphic image to change
VBScript
VBScript is an interpreted script language from Microsoft that is a subset of its Visual Basic programming language designed for interpretation by Web browsers.
VBScript is Microsoft's answer to Netscape's popular JavaScript. Both are designed to work with an interpreter that comes with a Web browser - that is, at the user or client end of the Web client/server session. VBScript is designed for use with Microsoft's Internet Explorer browser together with other programming that can be run at the client, including ActiveX controls, automation servers, and Java applets. Although Microsoft does support Netscape's JavaScript (it converts it into its own JScript), Netscape does not support VBScript. For this reason, VBScript is best used for intranet Web sites that use the Internet Explorer browser only.
Perl
Perl was originally said to stand for "Practical Extraction and Reporting Language" but that name is no longer used. Perl is a script programming language that is similar in syntax to the C language and that includes a number of popular Unix facilities such as SED, awk, and tr. Perl is an interpreted language that can optionally be compiled just before execution into either C code or cross-platform byte code. When compiled, a Perl program is almost (but not quite) as fast as a fully precompiled C language program. Perl is regarded as a good choice for developing common gateway interface (CGI) programs because it has good text manipulation facilities (although it also handles binary files). Larry Wall invented it.
Microsoft Front Page
FrontPage 2000, part of the Microsoft Office 2000 Premium package, allows you to create engaging Web sites that look and work exactly the way you want them to. FrontPage includes the ability to lay out pages with exacting care, design the pages with elements that color-coordinate, and use such cutting-edge features as dynamic HTML (DHTML) and cascading style sheets, which add style, movement, and interest to Web pages. The FrontPage Explorer, which is integrated into FrontPage 2000, makes it easy to manage the pages and the navigation structure of your Web site.
FrontPage also includes publishing features that make it easy to post your site to your Web server, as well as collaboration features. Because FrontPage 2000 preserves all foreign HTML, including formatting, you can use FrontPage 2000 to edit and enhance data access pages without any loss of functionality.
Cascading Style Sheets
A cascading style sheet (CSS) is a Web page derived from multiple sources with a defined order of precedence where the definitions of any style element conflict. The Cascading Style Sheet, level 1 (CSS1) recommendation from the World Wide Web Consortium (W3C), which is implemented in the latest versions of the Netscape and Microsoft Web browsers, specifies the possible style sheets or statements that may determine how a given element is presented in a Web page.
CSS gives more control over the appearance of a Web page to the page creator than to the browser designer or the viewer.
CorelDraw
Corel Draw is multi-media based application, instrumental in creation of graphics and animation.
Visual Basic For Applications (VBA)
A Visual Basic system included with Windows 95 applications and used for creating basic and customized programs.
Personal Home Page (PHP)
In Web programming, PHP is a script language and interpreter that is freely available and used primarily on Linux Web servers. PHP, originally derived from Personal Home Page Tools, now stands for PHP: Hypertext Preprocessor.
PHP is an alternative to Microsoft's Active Server Page (ASP) technology. As with ASP, the PHP script is embedded within a Web page along with its HTML. Before the page is sent to a user that has requested it, the Web server calls PHP to interpret and perform the operations called for in the PHP script.
Hyper Text Markup Language (HTML)
HTML 4.0 was the final version of the Hypertext Markup Language (HTML) before the Extensible Markup Language (XHTML) and remains the set of markup on which most large Web sites today are based. Like all HTML levels, HTML 4.0 was the official "recommendation" of the World Wide Web Consortium (W3C), the group that suggests industry standards for the Web.
Among new features introduced in HTML 4.0 were:
- The cascading style sheet, the ability to control Web page content at multiple levels
- The ability to create richer forms
- Support for frames (which is already supported by the major browsers)
- Enhancements for tables that make it possible to use captions to provide table content for Braille or speech users
- The capability to manage pages so that they can be distributed in different languages
In practice, the two leading browsers, Netscape and Internet Explorer, support HTML 4.0 somewhat differently or offer non-standard approaches. These require Web developers that use more advanced features to create pages for each browser and send the appropriate pages to the user
Java Server Pages (JSP)
Java Server Page (JSP) is a technology for controlling the content or appearance of Web pages through the use of servlets, small programs that are specified in the Web page and run on the Web server to modify the Web page before it is sent to the user who requested it. Sun Microsystems, the developer of Java, also refers to the JSP technology as the Servlet application program interface (API). JSP is comparable to Microsoft's Active Server Page (ASP) technology. Whereas a Java Server Page calls a Java program that is executed by the Web server, an Active Server Page contains a script that is interpreted by a script interpreter (such as VBScript or JScript) before the page is sent to the user.
Servlet
A servlet is a small program that runs on a server. The term was coined in the context of the Java applet, a small program that is sent as a separate file along with a Web (HTML) page. Java applets, usually intended for running on a client, can result in such services as performing a calculation for a user or positioning an image based on user interaction.
XML
XML (Extensible Markup Language) is a flexible way to create common information formats and share both the format and the data on the World Wide Web, intranets, and elsewhere. For example, computer makers might agree on a standard or common way to describe the information about a computer product (processor speed, memory size, and so forth) and then describe the product information format with XML. Such a standard way of describing data would enable a user to send an intelligent agent (a program) to each computer maker's Web site, gather data, and then make a valid comparison. Any individual or group of individuals or companies that wants to share information in a consistent way can use XML
Struts
Jakarta Struts, the premier framework for building Java-based Web applications. Using the model-view-controller (MVC) architecture, Struts solves many of the problems associated with developing Web applications using JavaServlets and JavaServer Pages. Consequently, costs are reduced and development time is enhanced through the re-use of software components and the implementation of a framework based on industry best practices.
J2EE
(Java 2 Platform, Enterprise Edition) is a Java platform designed for the mainframe-scale computing typical of large enterprises. Sun Microsystems (together with industry partners such as IBM) designed J2EE to simplify application development in a thin client tiered environment. J2EE simplifies application development and decreases the need for programming and programmer training by creating standardized, reusable modular components and by enabling the tier to handle many aspects of programming automatically.
J2EE includes many components of the Java 2 Platform, Standard Edition (J2SE):
The Java Development Kit (JDK) is included as the core language package.
Write Once Run Anywhere technology is included to ensure portability.
Support is provided for Common Object Request Broker Architecture (CORBA), a predecessor of Enterprise JavaBeans (EJB), so that Java objects can communicate with CORBA objects both locally and over a network through its interface broker.
Java Database Connectivity 2.0 (JDBC), the Java equivalent to Open Database Connectivity (ODBC), is included as the standard interface for Java databases.
A security model is included to protect data both locally and in Web-based applications.
J2EE also includes a number of components added to the J2SE model, such as the following:
- Full support is included for Enterprise JavaBeans.
- EJB is a server-based technology for the delivery of program components in an enterprise environment.
- It supports the Extensible Markup Language (XML) and has enhanced deployment and security features.
The Java servlet API (application programming interface) enhances consistency for developers without requiring a graphical user interface (GUI).
Java Server Pages (JSP) is the Java equivalent to Microsoft's Active Server Pages (ASP) and is used for dynamic Web-enabled data access and manipulation.
The J2EE architecture consists of four major elements:
- The J2EE Application Programming Model is the standard programming model used to facilitate the development of multi-tier, thin client applications.
- The J2EE Platform includes necessary policies and APIs such as the Java servlets and Java Message Service (JMS).
- The J2EE Compatibility Test Suite ensures that J2EE products are compatible with the platform standards.
- The J2EE Reference Implementation explains J2EE capabilities and provides its operational definition.
Weblogic
BEA Systems' WebLogic is a server software application that runs on a middle tier, between back-end databases and related applications and browser-based thin clients. WebLogic is a leading e-commerce online transaction-processing (OLTP) platform; developed to connect users in a distributed computing environment and to facilitate the integration of mainframe applications with distributed corporate data and applications.
WebLogic server is based on Java 2 Platform, Enterprise Edition (J2EE), the standard platform used to create Java-based multi-tier enterprise applications. J2EE platform technologies were developed through the efforts of BEA Systems and other vendors in collaboration with the main developer, Sun Microsystems. Because J2EE applications are standardized modules, WebLogic can automate many system-level tasks that would otherwise have demanded programming time.
The main features of WebLogic server include connectors that make it possible for any legacy application on any client to interoperate with server applications, Enterprise JavaBean (EJB) components, resource pooling, and connection sharing that make applications very scalable. An administration console with a user interface makes management tasks more efficient and features such as Secure Sockets Layer (SSL) support for the encryption of data transmissions, as well as authentication and authorization mechanisms, make applications and transactions secure.
WebSphere
WebSphere is a set of Java-based tools from IBM that allow customers to create and manage sophisticated business Web sites. The central WebSphere tool is the WebSphere Application Server (WAS), an application server that a customer can use to connect Web site users with Java applications or servlets. Servlets are Java programs that run on the server rather than on the user's computer as Java applets do. Servlets can be developed to replace traditional common gateway interface (CGI) scripts, usually written in C or Practical Extraction and Reporting Language, and run much faster because all user requests run in the same process space.
In addition to Java, WebSphere supports open standard interfaces such as the Common Object Request Broker Architecture (CORBA) and Java Database Connectivity (JDC) and is designed for use across different operating system platforms. One edition of WebSphere is offered for small-to-medium size businesses and another edition for larger businesses with a higher number of transactions. WebSphere also includes Studio, a developer's environment with additional components that allow a Web site's pages to be created and managed. Both editions support Solaris, Windows NT, OS/2, OS/390, and AIX operating systems.
Java Message Service (JMS)
Java Message Service (JMS) is an application program interface (API) from Sun Microsystems that supports the formal communication known as messaging between computers in a network. Sun's JMS provides a common interface to standard messaging protocols and also to special messaging services in support of Java programs. Sun advocates the use of the Java Message Service for anyone developing Java applications, which can be run from any major operating system platform.
The messages involved exchange crucial data between computers - rather than between users - and contain information such as event notification and service requests. Messaging is often used to coordinate programs in dissimilar systems or written in different programming languages.
Using the JMS interface, a programmer can invoke the messaging services of IBM's MQSeries, Progress Software's SonicMQ, and other popular messaging product vendors. In addition, JMS supports messages that contain serialized Java objects and messages that contain Extensible Markup Language (XML) pages.
J2ME: -
J2ME (Java 2 Platform, Micro Edition) is a technology that allows programmers to use the Java programming language and related tools to develop programs for mobile wireless information devices such as cellular phones and personal digital assistants (PDAs). J2ME consists of programming specifications and a special virtual machine, the K Virtual Machine that allows a J2ME-encoded program to run in the mobile device.
There are two programming specifications: Connected, Limited Device Configuration (CLDC) and the Mobile Information Device Profile (MIDP). CLDC lays out the application program interface (API) and virtual machine features needed to support mobile devices. MIDP adds to the CLDC the user interface, networking, and messaging details needed to interface with mobile devices. MIDP includes the idea of a midlet, a small Java application similar to an applet but one that conforms to CLDC and MIDP and is intended for mobile devices.
Devices with systems that exploit J2ME are already available and are expected to become even more available in the next few years.
Java Naming and Directory Interface (JNDI)
JNDI (Java Naming and Directory Interface) enables Java platform-based applications to access multiple naming and directory services. Part of the Java Enterprise application programming interface (API) set, JNDI makes it possible for developers to create portable applications that are enabled for a number of different naming and directory services, including: file systems; directory services such as Lightweight Directory Access Protocol (LDAP), Novell Directory Services, and Network Information System (NIS); and distributed object systems such as the Common Object Request Broker Architecture (CORBA), Java Remote Method Invocation (RMI), and Enterprise JavaBeans (EJB).
Common Object Request Broker Architecture (CORBA)
Common Object Request Broker Architecture (CORBA) is an architecture and specification for creating, distributing, and managing distributed program objects in a network. It allows programs at different locations and developed by different vendors to communicate in a network through an "interface broker." CORBA was developed by a consortium of vendors through the Object Management Group (OMG), which currently includes over 500 member companies. Both International Organization for Standardization (ISO) and X/Open have sanctioned CORBA as the standard architecture for distributed objects (which are also known as components). CORBA 3 is the latest level.
The essential concept in CORBA is the Object Request Broker (ORB). ORB support in a network of clients and servers on different computers means that a client program (which may itself be an object) can request services from a server program or object without having to understand where the server is in a distributed network or what the interface to the server program looks like. To make requests or return replies between the ORBs, programs use the General Inter-ORB Protocol (GIOP) and, for the Internet, it’s Internet Inter-ORB Protocol (IIOP). IIOP maps GIOP requests and replies to the Internet's Transmission Control Protocol (TCP) layer in each computer.
A notable holdout from CORBA is Microsoft, which has its own distributed object architecture, the Distributed Component Object Model (DCOM). However, CORBA and Microsoft have agreed on a gateway approach so that a client object developed with the Component Object Model will be able to communicate with a CORBA server (and vice versa).
Internet Inter-Orb Protocol (IIOP)
IIOP (Internet Inter-ORB Protocol) is a protocol that makes it possible for distributed programs written in different programming languages to communicate over the Internet. IIOP is a critical part of a strategic industry standard, the Common Object Request Broker Architecture (CORBA). Using CORBA's IIOP and related protocols, a company can write programs that will be able to communicate with their own or other company's existing or future programs wherever they are located and without having to understand anything about the program other than its service and a name. CORBA and IIOP are competing with a similar strategy from Microsoft called the Distributed Component Object Model (DCOM). (Microsoft and the Object Management Group, sponsors of CORBA, have agreed to develop software bridges between the two models so that programs designed for CORBA can communicate with programs designed for DCOM.
RMI (Remote Method Invocation)
RMI (Remote Method Invocation) is a way that a programmer, using the Java programming language and development environment, can write object-oriented programming in which objects on different computers can interact in a distributed network. RMI is the Java version of what is generally known as a remote procedure call (RPC), but with the ability to pass one or more objects along with the request. The object can include information that will change the service that is performed in the remote computer. Sun Microsystems, the inventors of Java, calls this "moving behavior." For example, when a user at a remote computer fills out an expense account, the Java program interacting with the user could communicate, using RMI, with a Java program in another computer that always had the latest policy about expense reporting. In reply, that program would send back an object and associated method information that would enable the remote computer program to screen the user's expense account data in a way that was consistent with the latest policy. The user and the company both would save time by catching mistakes early. Whenever the company policy changed, it would require a change to a program in only one computer.
Sun calls its object parameter-passing mechanism object serialization. An RMI request is a request to invoke the method of a remote object. The request has the same syntax as a request to invoke an object method in the same (local) computer. In general, RMI is designed to preserve the object model and its advantages across a network.
RMI is implemented as three layers:
- A stub program in the client side of the client/server relationship, and a corresponding skeleton at the server end. The stub appears to the calling program to be the program being called for a service. (Sun uses the term proxy as a synonym for stub.)
- A Remote Reference Layer that can behave differently depending on the parameters passed by the calling program. For example, this layer can determine whether the request is to call a single remote service or multiple remote programs as in a multicast.
- A Transport Connection Layer, which sets up and manages the request.
A single request travels down through the layers on one computer and up through the layers at the other end.
RMI is supplied as part of Sun Microsystems’s Java Development Kit (JDK).
Jini
Jini (pronounced DJEE-nee like the Arabic word for "magician") is a new idea that Sun Microsystems calls "spontaneous networking." Using the Jini architecture, users will be able to plug printers, storage devices, speakers, and any kind of device directly into a network and every other computer, device, and user on the network will know that the new device has been added and is available. Each plug gable device will define itself immediately to a network device registry. When someone wants to use or access the resource, his or her computer will be able to download the necessary programming from it to communicate with it. No longer will the special device support software known as a device driver need to be present in an operating system. The operating system will know about all accessible devices through the network registry.
Jini can be viewed as the next step after the Java programming language toward making a network look like one large computer. Jini promises to enable manufacturers to make devices that can attach to a network independently of an operating system like Windows 95. Equipped with its own small, special-purpose and possibly microchip-embedded operating system, a printer could be plugged into a network and immediately shared by users at a mix of computers: Windows, Macintosh, and UNIX. Mobile devices could be transported and easily plugged into a network so that others could use the device.
How It Works
Jini consists of four program layers:
- Directory Service
- JavaSpace
- Remote Method Invocation (RMI)
- Boot, Join, and Discover Protocol
Any device with an operating system that supports a Java can be plugged into the network. (For many devices, the operating system can be much smaller than Windows 2000, for example, since it is serving only the functions that device requires.) When a device is plugged into the Jini network, the Directory Service layer as a member of the network immediately registers it. Its necessary program objects are placed in a JavaSpace layer so that other network members can discover and download them when that network member wants to use the device. The actual communication with objects in JavaSpace is done using the Remote Method Invocation (RMI) interface and layer. The layer supporting the boot, join, and discover protocols enables devices, users, and applications to announce and register themselves and to discover others.
. Net Technologies
. NET is the Microsoft Web services strategy to connect information, people, systems, and devices through software. Integrated across the Microsoft platform, .NET technology provides the ability to quickly build, deploy, manage, and use connected, security-enhanced solutions with Web services. . NET-connected solutions enable businesses to integrate their systems more rapidly and in a more agile manner and help them realize the promise of information anytime, anywhere, on any device.
The Microsoft platform includes everything a business needs to develop and deploy a Web service-connected IT architecture: servers to host Web services, development tools to create them, applications to use them, and a worldwide network of more than 35,000 Microsoft Certified Partner organizations to provide support.
Microsoft .NET
Microsoft software for connecting information, people, systems, and devices. . NET provides XML-based interoperability and is being incorporated across Microsoft clients, servers, services, and tools. For example, products like Microsoft Windows and Microsoft Office will use .NET to connect with other systems and applications. For developers, .NET is manifested in the programming model delivered in the Microsoft .NET Framework.
Microsoft .NET Framework
An integral Windows component that enables building and running the next generation of software applications and Web services. It includes technologies for Web services and Web applications (ASP.NET), data access (ADO.NET), smart client applications (Windows Forms), and many others.
Microsoft Visual Studio .NET
An integrated development environment for helping developers to build scalable applications and Web services.
Distributed Component Object Model
Distributed Component Object Model (DCOM) is a programming model in which processing occurs in many different places (or nodes) around a network. Processing can occur wherever it makes the most sense, whether that is on a server, personal computer, handheld device, or other smart device. In contrast to the two-node system prevalent today (the client and the centralized server), Microsoft .NET uses distributed computing.
ASP.Net
ASP.NET (originally called ASP+) is the next generation of Microsoft's Active Server Page (ASP), a feature of their Internet Information Server (IIS). Both ASP and ASP.NET allow a Web site builder to dynamically build Web pages on the fly by inserting queries to a relational database in the Web page. ASP.NET is different than its predecessor in two major ways: it supports code written in compiled languages such as Visual Basic, C++, C#, and Perl, and it features server controls that can separate the code from the content, allowing WYSIWYG editing of pages. Although ASP.NET is not backwards compatible with ASP, it is able to run side by side with ASP applications. ASP.NET files can be recognized by their .asp extension.
Visual Basic .Net
Visual Basic .NET (VB.NET or VB .NET) is a version of Microsoft's Visual Basic that was designed, as part of the company's .NET product group, to make Web services applications easier to develop. According to Microsoft, VB .NET was reengineered, rather than released as VB 6.0 with added features, to facilitate making fundamental changes to the language. VB.NET is the first fully object-oriented programming (OOP) version of Visual Basic, and as such, supports OOP concepts such as abstraction, inheritance, polymorphism, and aggregation.
C
C is a structured, procedural programming language that has been widely used both for operating systems and applications and that has had a wide following in the academic community. Many versions of Unix-based operating systems are written in C. C has been standardized as part of the Portable Operating System Interface (POSIX).
With the increasing popularity of object-oriented programming, C is being rapidly replaced as "the" programming language by C++, a superset of the C language that uses an entirely different set of programming concepts, and by Java, a language similar to but simpler than C++, that was designed for use in distributed networks.
ActiveServerPages (ASP)
ASP is also an abbreviation for application service provider.
An Active Server Page (ASP) is an HTML page that includes one or more scripts (small-embedded programs) that are processed on a Microsoft Web server before the page is sent to the user. An ASP is somewhat similar to a server-side include or a common gateway interface (CGI) application in that all involve programs that run on the server, usually tailoring a page for the user. Typically, the script in the Web page at the server uses input received as the result of the user's request for the page to access data from a database and then builds or customizes the page on the fly before sending it to the requestor.
ASP is a feature of the Microsoft Internet Information Server (IIS), but, since the server-side script is just building a regular HTML page, it can be delivered to almost any browser. You can create an ASP file by including a script written in VBScript or JScript in an HTML file or by using ActiveX Data Objects (ADOs) program statements in the HTML file. You name the HTML file with the ".asp" file suffix. Microsoft recommends the use of the server-side ASP rather than a client-side script, where there is actually a choice, because the server-side script will result in an easily displayable HTML page. Client-side scripts (for example, with JavaScript) may not work as intended on older browsers.
For Web service applications, Microsoft provides a new version of ASP support called ASP.NET.
C++
C++ is an object-oriented programming (OOP) language that is viewed by many as the best language for creating large-scale applications. C++ is a superset of the C language. C++ is based on the paradigm of Object Oriented Programming (OOPS).
Visual C++
An application development tool developed by Microsoft for C++ programmers. Visual C++ supports object-oriented programming of 32-bit Windows applications with an integrated development environment (IDE), a C/C++ compiler, and a class library called the Microsoft Foundation Classes (MFC). The IDE includes an AppWizard, ClassWizard, and testing features to make programming easier
C#
C# (pronounced "C-sharp") is an object-oriented programming language from Microsoft that aims to combine the computing power of C++ with the programming ease of Visual Basic. C# is based on C++ and contains features similar to those of Java.
C# is designed to work with Microsoft's . NET platform. Microsoft's aim is to facilitate the exchange of information and services over the Web, and to enable developers to build highly portable applications. C# simplifies programming through its use of Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP) which allow access to a programming object or method without requiring the programmer to write additional code for each step. Because programmers can build on existing code, rather than repeatedly duplicating it, C# is expected to make it faster and less expensive to get new products and services to market.
Microsoft is collaborating with ECMA, the international standards body, to create a standard for C#. International Standards Organization (ISO) recognition for C# would encourage other companies to develop their own versions of the language. Companies that are already using C# include Apex Software, Bunka Orient, Component Source, devSoft, FarPoint Technologies, LEAD Technologies, ProtoView, and Seagate Software.
Web Services
Web services (sometimes called application services) are services (usually including some combination of programming and data, but possibly including human resources as well) that are made available from a business's Web server for Web users or other Web-connected programs. Providers of Web services are generally known as application service providers. Web services range from such major services as storage management and customer relationship management (CRM) down to much more limited services such as the furnishing of a stock quote and the checking of bids for an auction item. The accelerating creation and availability of these services is a major Web trend.
The three major components of Web Services are mentioned as below: -
SOAP (Simple Object Access Protocol)
Simple Object Access Protocol is a way for a program running in one kind of operating system (such as Windows 2000) to communicate with a program in the same or another kind of an operating system (such as Linux) by using the World Wide Web's Hypertext Transfer Protocol (HTTP) and its Extensible Markup Language (XML) as the mechanisms for information exchange. Since Web protocols are installed and available for use by all major operating system platforms, HTTP and XML provide an already at-hand solution to the problem of how programs running under different operating systems in a network can communicate with each other. SOAP specifies exactly how to encode an HTTP header and an XML file so that a program in one computer can call a program in another computer and pass it information. It also specifies how the called program can return a response.
SOAP was developed by Microsoft, DevelopMentor, and Userland Software and has been proposed as a standard interface to the Internet Engineering Task Force (IETF). It is somewhat similar to the Internet Inter-ORB Protocol (IIOP), a protocol that is part of the Common Object Request Broker Architecture (CORBA). Sun Microsystems' Remote Method Invocation (RMI) is a similar client/server interprogram protocol between programs written in Java.
An advantage of SOAP is that program calls are much more likely to get through firewall servers that screen out requests other than those for known applications (through the designated port mechanism). Since HTTP requests are usually allowed through firewalls, programs using SOAP to communicate can be sure that they can communicate with programs anywhere.
UDDI
UDDI (Universal Description, Discovery, and Integration) is an XML-based registry for businesses worldwide to list them on the Internet. Its ultimate goal is to streamline online transactions by enabling companies to find one another on the Web and make their systems interoperable for e-commerce. UDDI is often compared to a telephone book's white, yellow, and green pages. The project allows businesses to list themselves by name, product, location, or the Web services they offer.
Microsoft, IBM, and Ariba spearheaded UDDI. The project now includes 130 companies, including some of the biggest names in the corporate world. Compaq, American Express, SAP AG, and Ford Motor Company are all committed to UDDI, as is Hewlett-Packard, whose own XML-based directory approach, called e-speak, is now being integrated with UDDI.
While the group does not refer to itself as a standards body, it does offer a framework for Web services integration. The UDDI specification utilizes World Wide Web Consortium (W3C) and Internet Engineering Task Force (IETF) standards such as XML, HTTP, and Domain Name System (DNS) protocols. It has also adopted early versions of the proposed Simple Object Access Protocol (SOAP) messaging guidelines for cross platform programming.
In November 2000, UDDI entered its public beta-testing phase. Each of its three founders - Microsoft, IBM, and Ariba - now operates a registry server that is interoperable with servers from other members. As information goes into a registry server, servers in the other businesses share it. The UDDI beta is scheduled to end in the first quarter of 2001. In the future, other companies will act as operators of the UDDI Business Registry.
UDDI registration is open to companies worldwide, regardless of their size.
Database
A database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.
In computing, databases are sometimes classified according to their organizational approach. The most prevalent approach is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and subclasses.
The various types of database applications are mentioned as follows: -
Database Management Systems (DBMS)
A database management system (DBMS), sometimes just called a database manager, is a program that lets one or more computer users create and access data in a database. The DBMS manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and, in a multi-user system, which else may also be accessing the data. In handling user requests, the DBMS ensures the integrity of the data (that is, making sure it continues to be accessible and is consistently organized as intended) and security (making sure only those with access privileges can access the data). The most typical DBMS is a relational database management system (RDBMS). A standard user and program interface is the Structured Query Language (SQL). A newer kind of DBMS is the object-oriented database management system (ODBMS).
A DBMS can be thought of as a file manager that manages data in databases rather than files in file systems. In IBM's mainframe operating systems, the nonrelational data managers were (and are, because these legacy application systems are still used) known as access methods.
A DBMS is usually an inherent part of a database product. On PCs, Microsoft Access is a popular example of a single- or small-group user DBMS. Microsoft's SQL Server is an example of a DBMS that serves database requests from multiple (client) users. Other popular DBMS’s (these are all RDBMS’s, by the way) are IBM's DB2, Oracle's line of database management products, and Sybase's products.
DBase
A popular database management system produced by Ashton Tate Corporation. The dBase format for storing data has become a de facto standard, and is supported by nearly all database management and spreadsheet systems. Even systems that do not use the dBase format internally are able to import and export data in dBase format.
MS-Access
Access is a database application package, where data is stored in tables. Data can be inserted, updated, deleted. It is extensively used as a back end application.
Sybase
Sybase is a computer software company that develops and sells database management system (DBMS) and middleware products. Sybase products have found extensive application, particularly in commercial, industrial, and military communications systems.
RDBMS (Relational Database Management System)
A relational database management system (RDBMS) is a program that lets you create, update, and administer a relational database. Most commercial RDBMS's use the Structured Query Language (SQL) to access the database, although SQL was invented after the development of the relational model and is not necessary for its use.
The leading RDBMS products are Oracle, IBM's DB2 and Microsoft's SQL Server. Despite repeated challenges by competing technologies, as well as the claim by some experts that no current RDBMS has fully implemented relational principles, the majority of new corporate databases are still being created and managed with an RDBMS.
Oracle
It is the world's leading supplier of software for information management but it is best known for its sophisticated relational database products (notably Oracle9i), which are used in Fortune 1000 corporations and by many of the largest Web sites. Oracle's relational database was the world's first to support the Structured Query Language (SQL), now an industry standard.
Oracle targets high-end workstations and minicomputers as the server platforms on which to run its database systems. Along with Sun Microsystems, Oracle has long been a champion of network computers. It now boasts that it was the world's first software company to develop and deploy 100 percent Internet-enabled enterprise software across its entire product line: database, server, enterprise business applications, and application development and decision support tools.
Structured Query Language (SQL)
SQL (Structured Query Language) is a standard interactive and programming language for getting information from and updating a database. Although SQL is both an ANSI and an ISO standard, many database products support SQL with proprietary extensions to the standard language. Queries take the form of a command language that lets you select, insert, update, find out the location of data, and so forth. There is also a programming interface
Object Oriented Database Management Systems (OODBMS)
An object-oriented database management system (OODBMS) sometimes shortened to ODBMS for object database management system), is a database management system (DBMS) that supports the modeling and creation of data as objects. This includes some kind of support for classes of objects and the inheritance of class properties and methods by subclasses and their objects. There is currently no widely agreed-upon standard for what constitutes an OODBMS, and OODBMS products are considered to be still in their infancy. In the meantime, the object-relational database management system (ORDBMS), the idea that object-oriented database concepts can be superimposed on relational databases, is more commonly encountered in available products. An object-oriented database interface standard is being developed by an industry group, the Object Data Management Group (ODMG). The Object Management Group (OMG) has already standardized an object-oriented data-brokering interface between systems in a network. Postgres is an example of Object Relational Database Management Systems.
Postgres
PostgreSQL is a highly scalable, SQL compliant, open source object-relational database management system. With more than 15 years of development history, it is quickly becoming the de facto database for enterprise level open source solutions.
SAP (System Application Product)
SAP, started in 1972 by five former IBM employees in Mannheim, Germany, states that it is the world's largest inter-enterprise software company and the world's fourth-largest independent software supplier, overall. The original SAP idea was to provide customers with the ability to interact with a common corporate database for a comprehensive range of applications. Gradually, the applications have been assembled and today many corporations, including IBM and Microsoft, are using SAP products to run their own businesses.
SAP applications, built around their latest R/3 system, provide the capability to manage financial, asset, and cost accounting, production operations and materials, personnel, plants, and archived documents. The R/3 system runs on a number of platforms including Windows 2000 and uses the client/server model. The latest version of R/3 includes a comprehensive Internet-enabled package.
SAP has recently recast its product offerings under a comprehensive Web interface, called mySAP.com, and added new e-business applications, including customer relationship management (CRM) and supply chain management (SCM).
In early 2001, SAP, a publicly traded company, had 21,500 employees in over 50 countries, and more than 30,000 installations. SAP is turning its attention to small- and-medium sized businesses. A recent R/3 version was provided for IBM's AS/400 platform.
SAP R/3
R/3 is the comprehensive set of integrated business applications from SAP, the German company that states it is the market and technology leader in business application software. R/3 replaced an earlier system, R/2, which is still in use. R/3 uses the client/server model and provides the ability to store, retrieve, analyze, and process in many ways corporate data for financial analysis, production operation, human resource management, and most other business processes.
A recent release of R/3 makes it possible to get to the R/3 database and applications through Internet access and Web browsers. A sales representative can initiate the workflow for a sales order by filling out an electronic form on a laptop that will be "translated" into input for the R/3 system. Other interfaces such as Lotus Notes can also be used. The Web implementation adheres to the Workflow Client API standard of the Workflow Management Coalition (WfMC).
A more recent version of R/3 adds features designed to speed product delivery by helping to manage the supply chain.
SAP Modules
In the past when people were discussing SAP, the conversation very quickly boiled down to modules, for example:
SAP’s courses were structured along module lines so that you would attend MM 101, 102 and 103. While at the course you would learn many things about MM, but not much about the rest of the SAP system and how MM fits into it.
A conversation with a SAP recruiter might go something like this:
Recruiter … “which modules do you work with?”
Candidate … “well, I have a lot of purchasing process experience”
Recruiter … “yes, but which modules do you work with?”
Candidate … “well, it’s purchasing functionality … so that would be… umm. MM, FI and CO mainly”
Recruiter … “great I have just the job for you”
Candidate … “fantastic, is it purchasing?”
Recruiter … “well it says here that they want an MM, FI and CO person and that’s you, right?”
Not necessarily! A MM, FI, CO role might include Inventory Management (MM), Accounts Receivable (FI) and Profitability Analysis (CO) – none of which a purchasing person is guaranteed to have
Many programmer teams were organized along module lines, so that you would have a FI/CO, an MM and a HR team, for example. Training courses were (therefore) often prepared and delivered along module lines too. The result of this was that solutions were frequently optimized along module lines, and less often well integrated, and as for users, well, they were pretty much trained up in a module and left to get on with it post go-live. Fortunately those days are mostly passed, and more and more programmes (from design to build to training) are being organized along process lines such as:
- Order to Cash (including parts of SD, FI-AR and probably TY as well)
- Purchase to Pay (including MM-Purchasing and FI-AP)
- Record to Report (FI-GL etc)
SAP now are moving away from describing their system as a set of modules, and now are using the term ‘solutions’, which is much better. If you visit SAP’s website you will find that they have structured their Solutions tab as follows:
- Financials
- Human Resources
- Customer Relationship Management
- Supplier Relationship Management
- Product Lifecycle Management
- Supply Chain Management
- Business Intelligence
- The list of various SAP Modules is as follows: -
- FI Financial Accounting – essentially your regulatory ‘books of record’, including
- General ledger
- Book close
- Tax
- Accounts receivable
- Accounts payable
- Consolidation
- Special ledgers
- CO Controlling – basically your internal cost/management accounting, including
- Cost elements
- Cost centers
- Profit centers
- Internal orders
- Activity based costing
- Product costing
- AM Asset Management – track, value and depreciate your assets, including
- Purchase
- Sale
- Depreciation
- Tracking
- PS Project Systems – manage your projects, large and small, including
- Make to order
- Plant shut downs (as a project)
- Third party billing (on the back of a project)
- HR Human Resources – ah yes, people, including
- Employment history
- Payroll
- Training
- Career management
- Succession planning
- PM Plant Maintenance – maintain your equipment (e.g. a machine, an oil rig, an aircraft etc), including
- Labor
- Material
- Down time and outages
- MM Materials Management – underpins the supply chain, including
- Requisitions
- Purchase orders
- Goods receipts
- Accounts payable
- Inventory management
- BOM’s
- Master raw materials, finished goods etc
- QM Quality Management – improve the quality of your goods, including
- Planning
- Execution
- Inspections
- Certificates
- PP Production Planning – manages your production process, including
- Capacity planning
- Master production scheduling
- Material requirements planning
- Shop floor
- SD Sales and Distribution – from order to delivery, including
- RFQ
- Sales orders
- Pricing
- Picking (and other warehouse processes)
- Packing
- Shipping
- CA Cross Application – these lie on top of the individual modules, and include
- WF – workflow
- BW – business information warehouse
- Office – for email
- Workplace
- Industry solutions
- New Dimension products such as CRM, PLM, SRM, APO etc
Network
Network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain sub networks.
The most common topology or general configurations of networks include the bus, star, Token Ring, and mesh topologies. Networks can also be characterized in terms of spatial distance as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs).
Local Area Network (LAN)
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users (for example, in a home network) or as many as thousands of users (for example, in an FDDI network).
Major local area network technologies are:
- Ethernet
- Token Ring
- FDDI (Fiber Distributed Data Interface)
Ethernet
Ethernet is the most widely installed local area network (LAN) technology. Specified in a standard, IEEE 802.3, Ethernet was originally developed by Xerox from an earlier specification called Alohanet (for the Palo Alto Research Center Aloha network) and then developed further by Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Devices are connected to the cable and compete for access using a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.
Fast Ethernet or 100BASE-T provides transmission speeds up to 100 megabits per second and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1000 megabits per second (1 gigabit or 1 billion bits per second). 10-Gigabit Ethernet provides up to 10 billion bits per second.
Token Ring
A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second
The token scheme can also be used with bus topology LANs.
FDDI (Fiber Distributed Data Interface)
FDDI is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km (124 miles). The FDDI protocol is based on the Token Ring protocol. In addition to being large geographically, an FDDI local area network can support thousands of users. FDDI is frequently used on the backbone for a wide area network (WAN).
An FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbps capacity. If the secondary ring is not needed for backup, it can also carry data, extending capacity to 200 Mbps. The single ring can extend the maximum distance; a dual ring can extend 100 km (62 miles).
FDDI is a product of American National Standards Committee X3-T9 and conforms to the Open Systems Interconnection (OSI) model of functional layering. It can be used to interconnect LANs using other protocols. FDDI-II is a version of FDDI that adds the capability to add circuit-switched service to the network so that voice signals can also be handled. Work is underway to connect FDDI networks to the developing Synchronous Optical Network (SONET).
Metropolitan Area Network (MAN)
A metropolitan area network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.
Wide Area Network (WAN)
A wide area network (WAN) is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN).
The various types of Network Topologies are as follows: -
Bus Network Topology
A bus network is an arrangement in a local area network (LAN) in which each node (workstation or other device) is connected to a main cable or link called the bus. A bus network is simple and reliable. If one node fails to operate, all the rest can still communicate with each other. For a major disruption to take place, the bus itself must be broken somewhere. Bus networks are easy to expand. Additional nodes can be added anywhere along the bus.
There are several limitations to the bus network topology. The length of the bus is limited by cable loss. A bus network may not work well if the nodes are located at scattered points that do not lie near a common line. In situations like this, a ring network, mesh network, or star network may prove more flexible and more cost effective.
Star Network Topology
A star network is a local area network (LAN) in which all nodes (workstations or other devices) are directly connected to a common central computer. Every workstation is indirectly connected to every other through the central computer. In some star networks, the central computer can also operate as a workstation.
The star network topology works well when workstations are at scattered points. It is easy to add or remove workstations.
If the workstations are reasonably close to the vertices of a convex polygon and the system requirements are modest, the ring network topology may serve the intended purpose at lower cost than the star network topology. If the workstations lie nearly along a straight line, the bus network topology may be best.
In a star network, a cable failure will isolate the workstation that it links to the central computer, but only that workstation will be isolated. All the other workstations will continue to function normally, except that they will not be able to communicate with the isolated workstation. If any workstation goes down, none of the other workstations will be affected. But if the central computer goes down, the entire network will suffer degraded performance or complete failure. If redundancy is required, the mesh network topology may be preferable.
Mesh Network Topology
A mesh network is a local area network (LAN) that employs one of two connection arrangements, full mesh topology or partial mesh topology. In the full mesh topology, each node (workstation or other device) is connected directly to each of the others. In the partial mesh topology, some nodes are connected to all the others, but some of the nodes are connected only to those other nodes with which they exchange the most data.
A mesh network is reliable and offers redundancy. If one node can no longer operate, all the rest can still communicate with each other, directly or through one or more intermediate nodes. Mesh networks work well when the nodes are located at scattered points that do not lie near a common line.
The chief drawback of the mesh topology is expense, because of the large number of cables and connections required. In some scenarios, a ring network or star network may prove more cost effective than a mesh network. If all the nodes lie near a common line, the bus network topology is often the best alternative in terms of cost.
Token Ring Network Topology
A Token Ring network is a local area network (LAN) in which all computers are connected in a ring or star topology and a bit- or token-passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time. The Token Ring protocol is the second most widely used protocol on local area networks after Ethernet. The IBM Token Ring protocol led to a standard version, specified as IEEE 802.5. Both protocols are used and are very similar. The IEEE 802.5 Token Ring technology provides for data transfer rates of either 4 or 16 megabits per second
The token scheme can also be used with bus topology LANs.
Network Models
1) Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session. Other models with which it might be contrasted include the client/server model and the master/slave model. In some cases, peer-to-peer communications is implemented by giving each communication node both server and client capabilities. In recent usage, peer-to-peer has come to describe applications in which users can use the Internet to exchange files with each other directly or through a mediating server.
2) Client/server model describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. Although programs within a single computer can use the client/server idea, it is a more important idea in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations. Computer transactions using the client/server model are very common.
The client/server model has become one of the central ideas of network computing. Most business applications being written today use the client/server model. So does the Internet's main program, TCP/IP. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the "monolithic" centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client/server model and become part of network computing.
In the usual client/server model, one server, sometimes called a daemon, is activated and awaits client requests. Typically, multiple client programs share the services of a common server program. Both client programs and server programs are often part of a larger program or application. Relative to the Internet, your Web browser is a client program that requests services (the sending of Web pages or files) from a Web server (which technically is called a Hypertext Transport Protocol or HTTP server) in another computer somewhere on the Internet. Similarly, your computer with TCP/IP installed allows you to make client requests for files from File Transfer Protocol (FTP) servers in other computers on the Internet.
Network Protocols
When data is being transmitted between two or more devices something needs to govern the controls that keep this data intact. A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which hits and bytes are sent across wire) or high-level exchanges between application programs (e.g., the way in which two programs transfer a file across the Internet).
The most widely used protocols are as follows: -
HTTP: -
HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of protocols (the foundation protocols for the Internet).
HTTP concepts include (as the Hypertext part of the name implies) the idea that files can contain references to other files whose selection will elicit additional transfer requests. Any Web server machine contains, in addition to the Web page files it can serve, an HTTP daemon, a program that is designed to wait for HTTP requests and handle them when they arrive. Your Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a Uniform Resource Locator or URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the Internet Protocol address (IP address) indicated by the URL. The HTTP daemon in the destination server machine receives the request and sends back the requested file or files associated with the request. (A Web page often consists of more than one file.)
The latest version of HTTP is HTTP 1.1.
FTP
File Transfer Protocol (FTP), a standard Internet protocol, is the simplest way to exchange files between computers on the Internet. Like the Hypertext Transfer Protocol (HTTP), which transfers displayable Web pages and related files, and the Simple Mail Transfer Protocol (SMTP), which transfers e-mail, FTP is an application protocol that uses the Internet's TCP/IP protocols. FTP is commonly used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet. It's also commonly used to download programs and other files to your computer from other servers.
As a user, you can use FTP with a simple command line interface (for example, from the Windows MS-DOS Prompt window) or with a commercial program that offers a graphical user interface. Your Web browser can also make FTP requests to download programs you select from a Web page. Using FTP, you can also update (delete, rename, move, and copy) files at a server. You need to logon to an FTP server. However, publicly available files are easily accessed using anonymous FTP.
Basic FTP support is usually provided as part of a suite of programs that come with TCP/IP. However, any FTP client program with a graphical user interface usually must be downloaded from the company that makes it.
TCP/IP
TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.
TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.
TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. TCP/IP and the higher-level applications that use it are collectively said to be "stateless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being stateless frees network paths so that everyone can use them continuously. (Note that the TCP layer itself is not stateless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)
SMTP
SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving e-mail. However, since it is limited in its ability to queue messages at the receiving end, it is usually used with one of two other protocols, POP3 or IMAP that let the user save messages in a server mailbox and download them periodically from the server. In other words, users typically use a program that uses SMTP for sending e-mail and either POP3 or IMAP for receiving e-mail. On Unix-based systems, sendmail is the most widely used SMTP server for e-mail. A commercial package, Sendmail, includes a POP3 server. Microsoft Exchange includes an SMTP server and can also be set up to include POP3 support.
PPP
PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server. For example, your Internet server provider may provide you with a PPP connection so that the provider's server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. PPP uses the Internet protocol (IP) (and is designed to handle others). It is sometimes considered a member of the TCP/IP suite of protocols. Relative to the Open Systems Interconnection (OSI) reference model, PPP provides layer 2 (data-link layer) services. Essentially, it packages your computer's TCP/IP packets and forwards them to the server where they can actually be put on the Internet.
Serial Line Internet Protocol (SLIP)
SLIP is a TCP/IP protocol used for communication between two machines that are previously configured for communication with each other. For example, your Internet server provider may provide you with a SLIP connection so that the provider's server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you. Your dial-up connection to the server is typically on a slower serial line rather than on the parallel or multiplex lines such as a line of the network you are hooking up to.
A better service is provided by the Point-to-Point Protocol (PPP).
Network Security Terminologies
Access Control
Refers to mechanisms and policies that restrict access to computer resources. An access control list (ACL), for example, specifies what operations different users can perform on specific files and directories
Antivirus
A software program designed to identify and remove a known or potential computer virus
Application Gateway Firewall
Application gateways look at data at the application layer of the protocol stack and serve as proxies for outside users, intercepting packets and forwarding them to the application. Thus, outside users never have a direct connection to anything beyond the firewall. The fact that the firewall looks at this application information means that it can distinguish among such things as Telnet, file transfer protocol (FTP), or Lotus Notes traffic. Because the application gateway understands these protocols, it provides security for each application it supports.
Archiving
an archive is a collection of computer files that have been packaged together for backup, to transport to some other location, for saving away from the computer so that more hard disk storage can be made available, or for some other purpose. An archive can include a simple list of files or files organized under a directory or catalog structure (depending on how a particular program supports archiving).
Authentication
The process of determining the identity of a user that is attempting to access a network. Authentication occurs through challenge/response, time-based code sequences or other techniques
Authorization
The process of determining what types of activities or access is permitted on a network. Usually used in the context of authentication: once you have authenticated a user, they may be authorized to have access to a specific service.
Certificate Authority (CA)
A certificate authority is an authority in a network that issues and manages security credentials and public keys for message encryption and decryption. As part of a public key infrastructure (PKI), a CA checks with a registration authority (RA) to verify information provided by the requestor of a digital certificate. If the RA verifies the requestor's information, the CA can then issue a certificate.
Challenge-Response
A common authentication technique whereby an individual is prompted (the challenge) to provide some private information (the response). Most security systems that rely on smart cards are based on challenge-response. A user is given a code (the challenge), which he or she enters into the smart card. The smart card then displays a new code (the response) that the user can present to log in.
CHAP (Challenge-Handshake Authentication Protocol)
An authentication technique where after a link is established, a server sends a challenge to the requestor. The requestor responds with a value obtained by using a one-way hash function. The server checks the response by comparing it its own calculation of the expected hash value. If the values match, the authentication is acknowledged otherwise the connection is usually terminated.
Cryptography
A branch of complex mathematics and engineering devoted to protecting information from unwanted access. In the context of computer networking, cryptography consists of encryption, authentication, and authorization
DES (Data Encryption Standard)
A widely-used method of data encryption using a private (secret) key that was judged so difficult to break by the U.S. government that it was restricted for exportation to other countries. There are 72,000,000,000,000,000 (72 quadrillion) or more possible encryption keys that can be used. For each given message, the key is chosen at random from among this enormous number of keys. Like other private key cryptographic methods, both the sender and the receiver must know and use the same private key
DHCP (Dynamic Host Configuration Protocol)
DHCP enables individual computers on an IP network to extract their configurations from a server (the 'DHCP server') or servers, in particular, servers that have no exact information about the individual computers until they request the information. The overall purpose of this is to reduce the work necessary to administer a large IP network. The most significant piece of information distributed in this manner is the IP address.
Digital Certificate
A digital certificate is an electronic "credit card" that establishes your credentials when doing business or other transactions on the Web. It is issued by a certification authority (CA). It contains your name, a serial number, expiration dates, a copy of the certificate holder's public key (used for encrypting and decrypting messages and digital signatures), and the digital signature of the certificate-issuing authority so that a recipient can verify that the certificate is real.
Digital Signature
A digital signature is an electronic rather than a written signature that can be used by someone to authenticate the identity of the sender of a message or of the signer of a document. It can also be used to ensure that the original content of the message or document that has been conveyed is unchanged. Additional benefits to the use of a digital signature are that it is easily transportable, cannot be easily repudiated, cannot be imitated by someone else, and can be automatically time-stamped.
DMZ (de-militarized zone)
a network added between a protected network and an external network in order to provide an additional layer of security. Sometimes called a perimeter network.
DNS (Domain Name System)
The Internet protocol for mapping host names, domain names and aliases to IP addresses
Encryption
Scrambling data in such a way that it can only be unscrambled through the application of the correct cryptographic key.
Filter
A filter is a program or section of code that is designed to examine each input or output request for certain qualifying criteria and then process or forward it accordingly.
Firewall
A firewall is a program that protects the resources of one network from users from other networks. Typically, an enterprise with an intranet that allows its workers access to the wider Internet will want a firewall to prevent outsiders from accessing its own private data resources.
Gateway
A gateway is a network point that acts as an entrance to another network. In a company network, a proxy server acts as a gateway between the internal network and the Internet. A gateway may also be any machine or service that passes packets from one network to another network in their trip across the Internet.
Hubs
In describing network topologies, a hub topology consists of a backbone (main circuit) to which a number of outgoing lines can be attached ("dropped"), each providing one or more connection port for device to attach to. For Internet users not connected to a local area network, this is the general topology used by your access provider. Other common network topologies are the bus network and the ring network. (Either of these could possibly feed into a hub network, using a bridge.)
As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a local area network (for example, an Ethernet or a Token Ring), and a connection to a line.
Internet Key Exchange (IKE)
A hybrid protocol whose purpose is to negotiate, and provide authenticated keying material for, security associations in a protected manner. Processes, which implement this protocol, can be used for negotiating virtual private networks (VPNs) and also for providing a remote user from a remote site (whose IP address need not be known beforehand) access to a secure host or network.
IPSec (Internet Protocol Security)
A developing standard for security at the network or packet processing layer of network communication. IPSec provides two choices of security service: Authentication Header (AH), which essentially allows authentication of the sender of data, and Encapsulating Security Payload (ESP), which supports both authentication of the sender and encryption of data as well.
Key
In cryptography, a key is a variable value that is applied using an algorithm to a string or block of unencrypted text to produce encrypted text. The length of the key generally determines how difficult it will be to decrypt the text in a given message.
Public Key Infrastructure (PKI)
PKI (public key infrastructure) enables users of a basically insecure public network such as the Internet to securely and privately exchange data and money through the use of a public and a private cryptographic key pair that is obtained and shared through a trusted authority. The public key infrastructure provides for a digital certificate that can identify an individual or an organization and directory services that can store and, when necessary, revoke the certificates.
Network Information System (NIS)
NIS (Network Information System) is a network naming and administration system for smaller networks that was developed by Sun Microsystems. NIS+ is a later version that provides additional security and other facilities. Using NIS, each host client or server computer in the system has knowledge about the entire system. A user at any host can get access to files or applications on any host in the network with a single user identification and password. NIS is similar to the Internet's domain name system (DNS) but somewhat simpler and designed for a smaller network. It's intended for use on local area networks.
NIS uses the client/server model and the Remote Procedure Call (RPC) interface for communication between hosts. NIS consists of a server, a library of client programs, and some administrative tools. NIS is often used with the Network File System (NFS). NIS is a Unix-based program.
Public Key Cryptography
Asymmetric or public key cryptography is based on the concept of a key pair. Each half of the pair (one key) can encrypt information so that only the other half (the other key) can decrypt it. Only the designated owner knows one part of the key pair, the private key, the other part, the public key, is published widely but is still associated with the owner.
The public key infrastructure assumes the use of public key cryptography, which is the most common method on the Internet for authenticating a message sender or encrypting a message. Traditional cryptography has usually involved the creation and sharing of a secret key for the encryption and decryption of messages. This secret or private key system has the significant flaw that if the key is discovered or intercepted by someone else, messages can easily be decrypted. For this reason, public key cryptography and the public key infrastructure is the preferred approach on the Internet
RSA (Rivest-Shamir-Adleman)
One of the fundamental encryption algorithms or series of mathematical actions developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman. The RSA algorithm is the most commonly used encryption and authentication algorithm and is included as part of the Web browsers from Netscape and Microsoft.
Secure Hash Algorithm-1 (SHA-1)
A one-way cryptographic function, which takes a message, produces a 160-bit message digest. A message digest is a value generated for a message or document that is unique to that message, and is sometimes referred to as a "fingerprint" of that message or data. Once a message digest is computed, any subsequent change to the original data will, with a very high probability, cause a change in the message digest, and the signature will fail to verify. This process is used to compress large data strings to a 20-byte length, which is used in a cryptographic process. The reduced data length relieves computational requirements for data encryption.
VPN (Virtual Private Networking)
A VPN is a technology that overlays communications networks with a management and security layer. Though VPN technology, network managers can set up secure relationships while still enjoying the low cost of a public network such as the Internet.
Routers
A router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any gateway (where one network meets another), including each point-of-presence on the Internet. A router is often included as part of a network switch.
Switches
A digital switch is a device that handles digital signals generated at or passed through a telephone company central office and forwards them across the company's backbone network. It receives the digital signals from the office's channel banks that have been converted from users' analog signals and switches them with other incoming signals out to the wide area network.
BackUp Systems
ArcServe
BrightStor ARCserve Backup r11.1 delivers leading backup and restore protection for all classes of Windows, NetWare, Linux and UNIX servers, as well as Windows, Mac OS X, Linux, UNIX, AS/400 and VMS client environments. It’s easy to use, reliable and scalable, and delivers best-in-class functionality for DAS, NAS and SAN environments, as well as enhanced database and messaging functionality
BMC Patrol
PATROL is a performance and availability monitoring solution that enables you to improve service to your customers while driving down operational costs. You can quickly and cost-effectively integrate PATROL into your management environment. The solution provides QoS monitoring, notification and reporting across customers' servers, networks and application infrastructures. Self-provisioning, ease of use and out-of-the-box capabilities make PATROL Express easy to implement and inexpensive to operate.
Veritas
VERITAS Backup Exec™ 10 for Windows Servers is the Gold Standard in Windows data protection providing comprehensive, cost-effective, and certified backup and recovery - including the fastest disk-based recovery. An intuitive, web-based user interface simplifies installation and management of backup and remote servers with easy-to-use wizards.
Legato
Legato Solutions help organizations solve their data protection, high availability and email management challenges with award-winning backup software.
Tivoli Systems is an IBM-owned company that develops software that allows a business to manage its computing environment. In a large organization, keeping track of and upgrading computer equipment and various levels of operating systems and applications is a formidable task.
e-business infrastructure management
- E-marketplace solutions
- Industry-specific solutions
- Service provider capabilities
- Availability and application management
- Network management
- Operations management
- OS/390 management
Pervasive management (management of mobile devices and point-of-sale terminals)
Storage and storage area network (SAN) management
- Security management
- Service management
- Web management
Cisco Certifications
Cisco Certified Network Professional (CCNP)
Cisco Certified Network Professional (CCNP) is an intermediate-level certification in the Cisco certified professional program. This certification is aimed at full-time network or system administrators, or those who work with local and/or wide-area network (LAN/WAN) infrastructure.
Cisco Certified Network Associate (CCNA)
Cisco Certified Network Associate (CCNA) is an entry-level certification for the Cisco certified professional program. The certification is geared towards junior network administrators.
Cisco Certified Internetwork Expert (CCIE)
Cisco Certified Internetwork Expert (CCIE) is what Cisco describes as its "premium networking certification." The CCIE is widely regarded as having one of the toughest, most demanding exams. It includes both a written exam and a daylong lab exam. This certification is aimed at senior level networking professionals who design, build, implement, maintain, or troubleshoot complex enterprise networking infrastructures. CCIE recipients can specialize in routing and switching, communications and services, security, or voice systems and technologies.
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