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Connecting to the Digital Domain

Connecting to the Digital Domain. Chapter 4 Exploring the Digital Domain. Connecting to the Digital Domain. basics of data communication networks how the Internet provides global connectivity how WWW is a client/server app supported by the Internet how Web pages are hypermedia

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Connecting to the Digital Domain

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  1. Connecting to theDigital Domain Chapter 4 Exploring the Digital Domain

  2. Connecting to theDigital Domain • basics of data communication networks • how the Internet provides global connectivity • how WWW is a client/server app supported by the Internet • how Web pages are hypermedia • Web browser fundamentals • Web directories and search engines • keyword searching In this chapter, you will learn about . . .

  3. Data Communications Network A collection of computer systems configured to share digital data and resources

  4. Local Area Networks • LANs extend across limited geographical area • servers, terminals, etc.

  5. Internetwork • collection of autonomous networks • The Internet • intranets

  6. The Internet • evolved from an experimental DOD network created in the late 1960s • decentralized • loosely-coupled • redundant

  7. Internet Applications • e-mail • telnet • ftp (file transfer protocol) • World Wide Web

  8. World Wide Web • created as a medium for disseminating scientific research • organized by Tim Berners-Lee in 1989 • hypertext system • Documents with built-in cross-referencing called “hyperlinks” • open system

  9. Client/Server • CLIENT--(local) system requesting services • SERVER--(remote) system that receives and handles requests from many clients concurrently

  10. Web as Client/Server App • Protocol--a set of rules that govern how an activity takes place • HTTP--(HyperText Transfer Protocol) specifies how Web clients and servers communicate • URL--(Uniform Resource Locator) addressing for Web resources • HTML--(HyperText Markup Language) defines content and display of Web pages

  11. URL Example • protocol • Domain Name • resource location

  12. Web Browser (Client)

  13. Researching on the Web • Search service--generates lists of other Web sites containing information about supplied topics • Web directory--a search service organized as a topical hierarchy and compiled by (human) editors • Search engine--search services whose databases are compiled by automated Web crawlers

  14. Keyword Searching • A form of (automated) text matching • keyword--a word or phrase used as a text pattern for matching • hits--matches with text patterns • misses--fails to match some or all of the text pattern • false positives--hits that are not related to the desired topic

  15. Boolean Expressions • search engines interpret multiple keywords as Boolean expressions • AND--intersection, i.e., references that contain both keywords

  16. Boolean Expressions • OR--union, i.e., references that contain either keyword

  17. Boolean Expressions • NOT--negation, i.e., references that do not contain the keyword

  18. Mathematical Operators Mathematical operators may be used to signify Boolean expressions

  19. Hybrid Search Services • metasearch engines--consult other search engines and directories and summarize query data • niche services--commercial services targeted at a specific audience or topic • portals--gateway Web site with searching capabilities

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