Web Engineering An interim report for the Economic and Social - PowerPoint PPT Presentation

News to discuss? Internet May Be Just A Fad, Says European Body (04-Dez-00) http://www.newsbytes.com/news/00/158904.html Web Engineering An interim report for the Economic and Social Research Council (ESRC), says that the development of the Internet over the last decade may not be the epoch -making event that many have Prof. Dr. Dr. h.c. mult. Gerhard Krüger, Albrecht Schmidt said.... ... The report stems from the results of a two-year investigation Universität Karlsruhe into the use of the Internet, undertaken by the University of Warwick, which claims that there is already some evidence that Fakultät für Informatik the Net may be a passing fad, as usage among British Institut für Telematik teenagers is already starting to fall from its previously high levels. Wintersemester 2000/2001 The report speculates that as many as 2 million users of the Internet in the UK have stopped using it regularly because of the vast amounts of data online and the need to spend time on the Web to research that information.... Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 1 Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 3 Table of Contents 1. Introduction and History 2. Media and Information Web Engineering 3. Organizing Information 4. Access to Information and Navigation Chapter 3: The Web – An Information System � Methods for Information Access � Hypertext Navigation � Access Strategies for the Web 5. Describing and coding Information Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 2 Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 4

Methods for Information Access Quality of Search Results � addressing pages directly � recall = the ratio of documents retrieved versus the number of available documents relevant to the query, i.e., the fraction returned out of all desirable � search/browse in catalogs documents � search for keywords � precision = the ratio of the number of relevant documents retrieved versus the total number of � associative documents retrieved, or the useful fraction of what was actually retrieved � navigation � see information retrieval Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 5 Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 7 Search / Browse in Catalogs Addressing Pages Directly � browse predefined classes � search if classes/subclasses are unknown � requires unique addresses � less directed, open search strategy � URL: Uniform Resource Locator � if you can not specify what you are looking for ... � How to get listed in a catalog? � how to get the address? � automatically (submit in a certain category) � external channel, e.g. TV, radio, press, print, email, etc. � pages are manually selected, reviews, and added � guessing the DNS-name, e.g. � address of the catalog must be known www.uni-karlsruhe.de, www.oracle.com, www.linux.org � examples � conventions � yahoo.com � web.de � E.g. index.html, default.htm, robots.txt � lycos.de � netcenter.com � dmoz.org open directory project � and many others ... Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 6 Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 8

source: www.altavista.com Search for Keywords Incremental Search www.northernlight.com � concept map � refine search results � specific WWW server � categorizing results � search within results � parts of a search engine � robot/crawler � indexer � analyzer module � database � retrieval component � recommendation system � other user rank content � number of links to a page � how often is the page opened when displayed � etc ... Prof. Dr. Dr. h.c. mult . Ge rhard Krüger , Albrecht Schmidt: Web Engineering, WS00/01 page 9 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 11 Advanced Search Concepts I Search using a Query Language � specify search by � matching (exact, fuzzy) � mechanisms to search for keywords � search term � search term in: � keyword matching � term � title exclusion � query language � body � date � Boolean operators � domain � top level domain � “fuzzy operators” e.g. NEAR � link � domain � search for values of certain attributes � hostname � examples: www.altavista.com � language +domain:com +Netscape � country +url:Java +applet:* +host:www.ibm.com +confidential +image:sharon * +title:stone link:www.teco .uni-karlsruhe.de (image:bill NEAR clinton ) OR source: (image:clinton NEAR bill) OR www.google.com title:"Bill Clinton" Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 10 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 12

Advanced Search Concepts II Multimedia Search � searching for similar pages � content � images � video � audio � searching for pages that link to a page � based on � searching within a certain domain text/keywords � specialized search engines next to content � e.g. � www.altavista.com � www.ditto.com � music.lycos.com � multimedia.lycos.com source: � cached pages – no 404 www.google.com Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 13 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 15 Natural Language Search Associative � query a search engine in „plain“ English � semantic links in hypertext � links in text (related content) � icons and images � maps � different types of links � different semantics source: www.askjeeves.com Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 14 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 16

Search Functionality Hypertext – Navigational Patterns � providing a search function to visitors of a specific site (company web site, university site) � Navigational Design Patterns [Rossi et al. 98] � text based � when a users is on the site you want to help him to find � e.g. www.useit.com what he/she is looking for � landmark � two approaches „ Provide direct access to critical sub-systems in the Web Information System“ � search engine or directory � set-based navigation for the specific site „ Organize the information in Sets of related information items. � customized interface Provide intra-set navigation capabilities .“ � detailed inclusion � often combined landmark & set-based navigation and exclusion rules � e.g.: www.sun.com � using a „public“ search engine � e.g.: www.amazon.de with attributes to restrict the � metaphorical navigation search to this site � z.B.: www.iflyswa .com, www.hagebau.de � embedded in the site � also useful instead http://www8.org/w8-papers/5b-hypertext-media/improving/improving.html of a missing page Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 17 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 19 Hypertext - Navigation Text Based Navigation � links beyond content and semantic � navigational structure within the content � up, down, next, ... � often based on icon � author builds/defines this structure � tools for navigation � history, back/forward, home � bookmarks � in the user interface of the web client � navigational patterns Source: http://www.useit.com Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 18 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 20

Landmark & Set-based Navigation I Metaphorical Navigation I Source, 1998: http://www.iflyswa.com Source: http://www.amazon.de Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 21 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 23 Landmark & Set-based Navigation II Metaphorical Navigation II Source: http://www.wapforum .org Source: http://www.hagebau.de Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 22 Prof. Dr. Dr. h.c. mult . GerhardKrüger, Albrecht Schmidt: Web Engineering, WS00/01 page 24