WWW and HTTP

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WWW and HTTP



* The Hypertext Transfer Protocol (HTTP) is the main protocol used to access data on the World Wide Web (WWW).
* The World Wide Web is a repository of information spread all over the world and linked together.
* Hypertext and hypermedia are documents linked to one another through the con-cept of pointers.
* Browsers interpret and display a Web document.
* A browser consists of a controller, client programs, and interpreters.
* A Web document can be classified as static, dynamic, or active.
* A static document is one in which the contents are fixed and stored in a server. The client can make no changes in the server document.
* Hypertext Markup Language (HTML) is a language used to create static Web pages.
* Any browser can read formatting instructions (tags) embedded in an HTML document.
* A dynamic Web document is created by a server only at a browser request.
* The Common Gateway Interface (CGI) is a standard for creating and handling dynamic Web documents.
* A CGI program with its embedded CGI interface tags can be written in a language such as C, C++, shell script, or Perl.
* The server sends the output of the CGI program to the browser.
* The output of a CGI program can be text, graphics, binary data, status codes, instructions, or an address of a file.
* An active document is a copy of a program retrieved by the client and run at the client site.
* Java is a combination of a high-level programming language, a run-time environment, and a class library that allows a programmer to write an active document and a browser to run it.
* Java is used to created applets (small application programs).
* Java is an object-oriented typed language with a rich library of classes.