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

2. 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 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. 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 Boolean ExpressionMathematical Operator Labrador AND retrievers+Labrador +retrievers Labrador AND NOT retrievers +Labrador -retrievers 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