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The World Wide Web

• Architectural Overview

• Static Web Documents

• Dynamic Web Documents

• HTTP – The HyperText Transfer Protocol

• Performance Enhancements

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Architectural Overview

The parts of the Web model.

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The Client Side

(a) A browser plug-in. (b) A helper application.

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Typical Server Processing Module

1. Resolve the name of the Web page requested

2. Authenticate the client

3. Perform access control on the client

4. Perform access control on the Web page (.htaccess)

5. Check the cache

6. Fetch the requested page from disk

7. Determine the MIMI type to include in the response

8. Take care of miscellaneous odds and ends

9. Return the reply to the client

10.Make an entry in the server log

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The Server Side

A multithreaded Web server with a front end and processing modules.

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The Server Side (2)

A server farm.

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The Server Side (3)

(a) Normal request-reply message sequence.

(b) Sequence when TCP handoff is used.

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URLs – Uniform Resource Locaters

Some common URLs.

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Statelessness and Cookies

Some examples of cookies.

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Static Web Documents

•HTML – HyperText Markup Language

•Forms

•XML and XSL

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XML and XSL

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XML and XSL (2)

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Dynamic Web Documents

Steps in processing the information from an HTML form.

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Dynamic Web Documents (2)

A sample HTML page with embedded PHP.

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Client-Side Dynamic Web Page Generation

(a) Server-side scripting with PHP.(b) Client-side scripting with JavaScript.

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Client-Side Dynamic Web Page Generation (5)

The various ways to generate and display content.

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HTTP Methods

The built-in HTTP request methods.

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HTTP Methods (2)

The status code response groups.

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Example HTTP Usage

The start of the output of www.ietf.org/rfc.html.

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Caching

Hierarchical caching with three proxies.