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Types of Web browsers and Servers - Digital Communication


A Web browser is a program you use to view pages on and navigate the World Wide Web. Browsers are sometimes referred to as Web clients or other fancy names ('Internet navigation tools'), but Web browser is the most common term.

A wide range of Web browsers is available for every type of system you can imagine, including graphical-user-interface, and text-only for dial-up UNIX connections. Most browsers are freeware. Usually, all you have to do is to get a browser downloaded from the Internet. For example, the Internet Explorer 6.0 version comes free as part of Windows XP.

Types of Web browsers and Servers - Digital Communication

Currently, the most popular browsers for the World Wide Web are Netscape's Navigator, developed by Netscape Communications Corporation, and Internet Explorer developed by Microsoft Corporation. a Web browser does the following two types of services:
  1. Given a URL address, it should be able to access that information, For hypertext Web documents, this means that the browser must be able to communicate with the Web browser using the HTTP protocol.
  2. Because the Web can also manage information contained on FTP and Gopher servers, in Usenet news postings, in e-mail, and soon, browsers can often communicate with those servers or protocols as well.

Different browsers may format and display the same file differently, depending on the capabilities of the hardware and the default layout options for the browser itself.

Retrieving documents from the Web and formatting them for your system are the two tasks that make up the core of a browser's functionality. However, depending on the browser you use and the features it includes, you may also be able to play multimedia files, view and interact with Java applets, read your mail, or use other advanced features that a particular browser offers.


Popular Web Browsers



NCSA Mosaic

A few years ago, Mosaic had Netscape's place on the Web as the most popular browser. As a matter of fact, Mosaic was the first full-color graphical browser and is instrumental in making the Web as popular as it is today. Mosaic was developed by NCSA at the University of Illinois, with several supported commercial versions available from companies such as Spry and Spyglass. NCSA Mosaic is free for personal use and comes in versions for Windows, Macintosh, and UNIX (the X Window System). Each version is colloquially called WinMosaic, MacMosaic, and XMosaic respectively.

Lynx

If the only connection you have to the Internet is through a dial-up text-only UNIX (or other) account, you are limited to using text-only browsers such as Lynx. you will not be able to view documents in color or view graphics online. Lynx was originally developed by the University of Kansas and now by Fotos Macrides at the Worcester Foundation for Biological Research.

It is an excellent browser for text-only Internet connections such as dial-up UNIX accounts. It requires VT100 terminal emulation, which most terminal emulation programs should support. you can use arrow keys to select links on Web pages. Because Lynx runs on systems that lack the ability to display graphics, viewing Web pages using Lynx gives you nothing but the text and the links. Designing pages that work equally well in Lynx and in graphical browsers is one of the more interesting challenges of Web page design.

Lynx is the ideal solution for people who either do not have a direct Internet connection or do not want to take time to use the Web graphically. It is fast and it enables you to get hold of just about everything on the Web.

Netscape Navigator

Netscape Navigator also familiarly known as Netscape is available for Windows, Macintosh, and for many different versions of UNIX running the X Window System. It is well supported and provides up-to-the-minute features including an integrated news and mail reader, support for Java applets, and the ability to handle "plug-ins" for more new and interesting features yet to be developed.

Microsoft Internet Explorer

New on the scene but expected to make a significant impact in the coming months is Microsoft's new browser Internet Explorer, usually just called Explorer. Explorer runs on all versions of Windows OS, and Macintosh, and it is free for download from Microsoft's Web site (http://www.microsoft.com/ie/).

Mozilla Firefox 2.0

Mozilla Firefox is a fast, full-featured Web browser that makes browsing very efficient. Firefox includes pop-up blocking, tab-browsing, integrated Google searching, simplified privacy controls that let you cover your tracks more effectively. A streamlined browser window that shows you more of the page than any other browser and a number of additional features that work with you to help you get the most out of your time online. This is also available for free.

WWW Servers

To make available the services of Web pages, Web sites need a host, a computer, and server software that runs on the host. The host manages the communication protocols and the related software required to create a Website on the Internet. The host machine often uses the UNIX, Windows NT, Windows 2000, or Macintosh Operating systems which have the TCP/IP protocols built in. The server software resides on the host and serves up the pages and otherwise acts on the requests sent from the client browser software.

A Web server is a program that runs on a Website and is responsible for replying to Web browser requests for files. you need a Web server to publish documents on the Web.

Types of Servers

There are different types of server software (database servers or network servers, etc) that perform different types of services for different types of clients. Specifically, a Web server is an HTTP server and its function is to send information to the client software (typically a browser) using the Hypertext Transfer Protocol (HTTP). The client browser requests and the server returns and Hypertext Markup Language (HTML) document. The server receives this request and sends back a response.

Functions performed by Web Server

A web server does the following jobs:
It passes requests to run CGI (Common Gateway Interface) scripts to the CGI applications. These scripts run external mini-programs, such as a database lookup or interactive forms processing.
The server software includes configuration files and utilities to secure and manage the Website in a variety of ways.

Working of Web Server Software

Client (Internet browser) software sends its request for data to the host, and the Web server software processes the request. Included in the browser's request are the desired information and the file formats the browser can accept. If the browser asks for an HTML file, the Web server retrieves the file, attaches a header to the file, and sends it to the browser.

If the browser has asked for specific database information, the Web server will pass a request through CGI to the application, which performs a database lookup. The CGI script returns the result to the Web server, which in turn attaches a header to the data and sends it to the browser.

The host computer must have a uniques IP address to send and receive information across the Internet.

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