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Web Programming

Notes
Figure 1.6: The Web Client Communicates with the Web
Server using an HTTP Virtual Circuit

Web Client Web Server

Virtual
HTTP HTTP

Connection

TCP/IP Internet TCP/IP
Protocol Protocol
Suite Suite

Details of HTTP can be found in the following Request for comments (RFC):

 HTTP 1.0 specifications are described in RFC 1945:
http://www.cis.ohio-state.edu/htbin/rfc/rfc1945.html
 MIME specifications are described in RFC 1521:
http://www.cis.ohio-state.edu/htbin/rfc/rfc1521.html

1.8.2 Hypertext: The Motion of the Web

The operation of the Web relies primarily on hypertext as its means of information retrieval.
HyperText is a document containing words that connect to other documents. These words are
called links and are selectable by the user. A single hypertext document can contain links to many
documents. In the context of the Web, words or graphics may serve as links to other documents,
images, video, and sound. Links may or may not follow a logical path, as each connection is
programmed by the creator of the source document. Overall, the WWW contains a complex
virtual web of connections among a vast number of documents, graphics, videos and sounds.

Producing hypertext for the Web is accomplished by creating documents with a language called
Hyper Text Markup Language, or HTML. With HTML, tags are placed within the text to accomplish
document formatting, visual features such as font size, italics and bold, and the creation of
hypertext links. Graphics may also be incorporated into an HTML document. HTML is an evolving
language, with new tags being added as each upgrade of the language is developed and released.

Notes The World Wide Web Consortium, led by Tim Berners-Lee, co-ordinates the efforts
of standardising HTML.

1.8.3 Understanding Hypertext Markup Language (HTML)

The Hypertext Markup Language is a document-layout, hyperlink specification, and markup
language. Web clients use it to generate resource requests for Web servers, and to process output
returned by the Web server for presentation. A markup language described what text means and
what it is supposed to look like. Figure 1.7 shows where the HTML layer fits into Web clients.

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