WWW Functions

Presentations at the SKYPE conversation conference on 16^th July 2008

World Wide Web

Appeared in eighties of the last century

1991 is the date of the WWW debut as a publicly available service on the Internet

WWW founder is Sir Timothy Berners-Lee (then worked at CERN in Geneva, Switzerland)

Now Berners-Lee heads the World Wide Web Consortium (W3C)

WWW basic ideas

Prepared by Galina Vitkova

Hypertext – a format of information, which enables to move from one part of a dokument toanother OR from one dokument to another through internal connections (hyperlinks)

Resource Identifiers –unique identifiers for locating a resource (computer file, document etc.)

Client-server model of computing – client software or a client computer makes requests of server software or a server computer that provides the client with resources or services

Markup language – characters or codes embedded in a text

How the Web works

1^st step: Type URL into browser OR Follow hyperlink

Behind the screen:

· server part of URL is resolved into IP address by DNS

· browser establishes TCP connection

2^nd step: HTTP request is sent to the server:

· HTML text is parsed by browser, it makes add. requests (graphics, other fines, etc.)

· Browser renders the page by HTML, CSS, etc., incorporates images, as a result produces on-screen page

Web standards

By Patrik Majkowski

• set of standardized best practices for building web sites
• need for web standards emerged when there was more than one major web browser
• standards allow constant look of web pages when using a range of browsers
• standards are adopted after extensive consensus-building
• when some browsers don’t respect standards correctly, webmasters must use hacks and tricks to make pages look similar in their browsers
• earlier versions of Internet Explorer are known not to respect standards of that time
• the most rigorous test for web standards is called ACID test (http://www.acidtests.org/ )

even today, only a few browsers pass the ACID test with 100% score