Linux as a webserver

Linux as a Webserver (Apache) (QLX25)

IBM Learning Services

Unit 1 Web Service Concepts

Objectives
Describe the history of the Internet and World Wide Web Describe advantages and disadvantages of the HTTP protocol Describe how different WWW languages and protocols relate Describe the advantages of the Apache server

History of the Internet
Created in 1973 Originally a researchproject funded by the U.S. Department of Advanced Research Projects Agency (DARPA) Original goal: design a distributed fault-tolerant network New protocol suite created (TCP/IP) TCP - Transmission Control Protocol IP - Internet Protocol many other protocols make up the suite Internet is based on TCP/IP

What Is the Internet?
Interconnected network of networks spanning the globe Vendor andplatform independent No one organization controls the Internet Made up of companies and organizations, and many different network types

First Uses for the Internet
First applications tended to be textual Telnet (login to remote machines) FTP (transfer files between machines email - Electronic Mail Talk - Interactive chat Usenet - Distributed discussion groups Gopher - Distributed text informationArchie - Distributed FTP server information

What is Hypertext?
Document Document Document

LINK

LINK

LINK LINK Document Document

LINK

Interactive Distributed Information
Documents stored on servers Links in documents allow references to documents which may be stored on other servers Gopher - First version Text based Minimal formatting Not visually appealing (static content)Links allow access to documents on other servers World Wide Web (WWW) - Second version Text based (with formatting hints) Graphics embedded with text Visually appealing (static and dynamic content) Links allow access to documents on other servers

Birth of the World Wide Web
1990 - World Wide Web (WWW) was born Tim Berners-Lee while working at the European Organization for Nuclear Research (CERN)Original browser and server ran on NeXT computers 1993 - National Center for Supercomputing Applications (NCSA) releases Mosaic web browser Multiplatform X Windows (Motif) Microsoft Windows Apple Macintosh December 1993 - There were 200 Web sites!

How Does the WWW Work?

Internet
Web Server
Request Response

Web Browser

Web Browser

Client/Server and the WWW
WWW follows TCP/IPdefinition of client/server client = machine requesting a service server = machine providing a service Client - Web Browser Runs on local computer Formats and displays the document Interacts with the user Original browser was NCSA Mosaic Today we have many (Netscape, Mozilla, Arena, Opera, Galeon, Konqueror, Lynx/Links, MSIE) Server - Web Server Delivers documents to the Web browser Executes programson the server Original Web server was NCSA httpd Today we have many (Apache, iPlanet, IIS)

Content Format
HyperText Markup Language (HTML) Describes the sections of a document Does not describe the format Browser is responsible for formatting Other markup languages exist SGML XML DHTML XHTML

HTML Advantages
Simple Language made up of "tags" easy to write from scratch, or generate from aprogram Lightweight text tags; quick to send on a network Portable browser independent (to a certain degree) open spec, can be implemented by anyone can be integrated in other programs (email, word processors, etc.) Flexible easy to create visually appealing web pages Latest version: HTML 4.0

HTML Disadvantages
Formatting decisions are handled by browser each can interpret the tabsdifferently, resulting in different output Web authors must take all browsers into account when writing pages; extra programming effort Different vendors add their own extensions to HTML; don't follow the standards laid out by W3C Leads to pages that only are visible in one browser

How Are Web Pages Transferred?
HyperText Transfer Protocol (HTTP) Communications protocol used between browser and...