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CE80N Introduction to Networks & The Internet

CE80N Introduction to Networks & The Internet. Dr. Chane L. Fullmer UCSC Winter 2002. General Information. TA Office… Trailer #15 is no more TA offices moved to the ISB Contact TA for current info…. Web Search based Essay. Essay based on Web search results

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CE80N Introduction to Networks & The Internet

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  1. CE80NIntroduction to Networks&The Internet Dr. Chane L. Fullmer UCSC Winter 2002

  2. General Information • TA Office… • Trailer #15 is no more • TA offices moved to the ISB • Contact TA for current info… CE80N -- Lecture #15

  3. Web Search based Essay • Essay based on Web search results • 1-2 pages on any topic of interest • Must include results from at least four Web page references • References must be listed in a bibliography • Due Today, February 26, 2002 CE80N -- Lecture #15

  4. Class Information • Web page tutorial available on-line • Web page submission: • Email to venkat@cse.ucsc.edu • Subject: cmpe080n-assgn4 • Final Exam • Last class session • March 14, 2002 CE80N -- Lecture #15

  5. Personal Web Page of the Day • A few brave souls…. • So, here’s: • Robbie Stockman • Ryan Rodriguez CE80N -- Lecture #15

  6. Description Of Functionality An automated search service allows one to find information that resides on remote computers. CE80N -- Lecture #15

  7. Browsing Vs. Automated Searching • The size of the Internet makes it impossible to find specific information by searching one computer at a time. • Called Browsing, like window shopping at the mall • The solution is to use an automated search engine. • Like using the yellow pages and calling from home. CE80N -- Lecture #15

  8. A Search Engine Helps Users Get Started • Automated searching is especially helpful when a user first begins to explore a topic. CE80N -- Lecture #15

  9. A Search Tool Can Help Recover From Loss • Automated search tools help users recover quickly when the location of information is lost. CE80N -- Lecture #15

  10. Automated Searching By Name • One can search by specific name or content. • NetScape -- search site • Overture (formerly Goto.com) CE80N -- Lecture #15

  11. How An Automated Search Service Operates • Search engines: • gather information globally • store it locally • Servers do not have to search the entire Internet when responding to a user’s request. • Caveat – Information can get stale… CE80N -- Lecture #15

  12. Figure 25.1 An illustration of the two-step process an automated search service uses. (a) A spider program automatically contacts web sites and obtains a list of available items. (b) When someone uses a browser to contact the search engine, the server consults the database on its local disk. Figure 25.1

  13. Modern Systems Search Web Page Contents • Users can assume the search will look for Web pages matching the topic specified. CE80N -- Lecture #15

  14. How A Web Search Appears To A User • Search services are: • Accessed through a Web site • Search services: • Require user interaction • Use forms technology • NetScape Search Site CE80N -- Lecture #15

  15. How A Search Engine Returns Results • The search engine creates a Web page that has a link to each found topic. • Uses cgi technology to create pages dynamically CE80N -- Lecture #15

  16. Automated Search Services Use String Matching • The simplest automated search mechanism is string matching. • The user enters a topic, the search engine finds Web pages that contain that topic string. Google.com CE80N -- Lecture #15

  17. String Matching • Advantages of string matching • Simplicity • Disadvantage of string matching • Lack of semantics • Inability to tell the meaning of words • “This sentence is NOT about trains, planes and automobiles” CE80N -- Lecture #15

  18. Advanced Search Programs • Some search engines offer multi-key search service. • Group synonyms with a common theme together • ie, hospital doctor nurse health CE80N -- Lecture #15

  19. Advanced Services- More Sophisticated Matching • Some services offer the opportunity to give more detailed specifications. • Use plus sign to denote a required term • Lycos CE80N -- Lecture #15

  20. Personalized Search Results • Search engines keep information about users and use the information to select and order search results. • Results in different users getting different search results on same keys CE80N -- Lecture #15

  21. How An Automated Content Search Works • The search service runs a program called a spider. • Explores Web • Compiles a list of topics • Stores list on server disk • Filters out articles, prepositions from text as one way to avoid storing useless information. CE80N -- Lecture #15

  22. Searches Are Restricted • Automated search services search only the beginning of each page. • Use the special HTML tag: • <META name=“my travel” content=“travel, air, sea, tickets”> • Allows specific keywords that do not appear in the browser • Gives the site better coverage from search engines CE80N -- Lecture #15

  23. Advertising Pays For Searching • Web searching appears to be free. • Uses advertising to generate revenue CE80N -- Lecture #15

  24. Example of Automated Search Services Figure 25.4 Examples of automated search services available on the World Wide Web. Although most services provide a general index to Web pages, a few are restricted to specific types of information. • Infoseek Site • Dogpile • WebCrawler

  25. Significance Of Automated Web Search • Automated search engines have become an essential part of finding information. • Growing rapidly on the Internet • A gigantic, freely accessible, global database at your disposal, 24/7….. CE80N -- Lecture #15

  26. Glossary • Personalized Search Results • Results from a search engine that are personalized to the user who makes the request. Personalization depends on a history of searches and web accesses. CE80N -- Lecture #15

  27. Glossary • Wide Area Information Server • (WAIS) An early automated search service that permitted one to locate documents that contain key words or phrases. CE80N -- Lecture #15

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