World Wide Web

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World Wide Web

• COMP 101
• Spring Semester, 2006
• (Last Modified 2006/2/16)

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A computer system
Applications
Operating System
Device Drivers
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A killer application

• Invented by Tim Berners-Lee at CERN around 1990
• Based on the hypertext concept
• Allows information retrieval over the Internet
  with little training
• Handles text, graphics, voice, video, programs,
  etc.
• Supports various levels of privacy

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Popular browsing tools

• Microsoft Internet Explorer (IE)
• Netscape Communicator
• Mozilla
• Opera (for mobile devices)
• A few research browsers, such as the W3C Amaya

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Basic elements of WWW

• Each information repository must have a unique
  Internet address called the Uniform Resource
  Locator (URL) (e.g., www.cs.ust.hk).
• The address (not necessarily starting with www)
  is registered with a Web server at the users
  organization or at an Internet service provider.
• A data file may contain URL links to other
  relevant information repositories.

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Information on the WWW

• Coded in the Hyper Text Markup Language (HTML) or
  its descendants
• Transferred using the Hyper Text Transfer
  Protocol (HTTP)

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Finding information on WWW

• www.google.com
• www.yahoo.com
• And many others that use Web crawlers to follow
  links and index the keywords for fast retrieval
• Funded mainly by advertisers
• Use Boolean operators (AND, OR, NOT) to limit
  searches

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Privacy on the WWW

• Web servers often use cookies to track users
  browsing habits.
• Cookies are small files placed by the Web server
  in a directory of the users computer.
• A cookie is meaningful only to the Web server who
  placed it there.
• A privacy concern?

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Business transactions on WWW

• Use secure connection (https) before entering
  personal data.
• Make sure the company/site is legitimate.

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Governance of the WWW

• World Wide Web Consortium (W3C) for standards
• World Wide Web Conference (WWWn) for latest
  development

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Future of the WWW

• Services, in addition to contents
• Machines, in addition to people

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Technology evolution
Internet
Services on demand
WWW
Web services
HTML
WSDL SOAP UDDI
OGSA
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Maturing technology

• Internet e-mails and file transfers
  (human-to-human through machines)
• WWW getting information (human-to-machine)
• Web services getting work done
  (machine-to-machine)
• Grid computing computing on demand (future
  possibility)

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Building a SUPER Web

• SafeNo violation of privacy
• UsableEqual access by all
• ProductiveRaising levels of abstraction
• EconomicalRewards to contributors
• RobustResistance to sporadic failures