Technologies and the Information ProfessionsWeb-Based .ppt

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1、School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,LIS 386.13 Information Technologies and the Information Professions Web-Based Databases,R. E. Wyllys Last revised 2003 Apr 22,School of Information - The University of Texas a

2、t Austin LIS 386.13, Information Technologies & the Information Professions,Lesson Objectives,You will Understand the four main types of uses of databases on the World-Wide Web Become familiar with some of the tools and techniques involved in developing Web-based databases (WBDBs),School of Informat

3、ion - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,What Do WBDBs Do?,What are the purposes for which WBDBs are used? Feiler (1999) distinguishes four main purposes: “Publishing data on the Web.“ “Here, you use the Web as a publication tool; bro

4、wsers interact with dynamic hypertext markup language DHMTL, application servers, and database queries to present the information as requested. The data flow is one way: from the database to the user.“ “Sharing data on the Web.“ “In this scenario you use databases and the Web to share data among peo

5、ple; the data flow is bidirectionalsome people enter data, other people look it up.“,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,What Do WBDBs Do? (contd),“E-commerce.“ “This area includes all online commercial transact

6、ions. Although the data flow is bidirectional, it typically consists of a relatively large amount of data that flows from the database to the customer (during the shopping and evaluation steps); that is followed by a relatively small amount of data that flows from the customer to the database as the

7、 sale is consummated.“ “Totally database-driven Web sites.“ “You can use databases to generate Web pages and keep them up to date. In this case, the database is usually invisible to the user; it is a behind-the-scenes assistant to a Web site.“,School of Information - The University of Texas at Austi

8、n LIS 386.13, Information Technologies & the Information Professions,WBDBs Used for Publishing on the Web,Here are some examples, from A to Z, of WBDBs whose primary purpose is publishing information. I recommend that you look at these WBDBs bearing that purpose in mind, and that you think about how

9、 they succeed or fail in achieving the purpose. WBDBs on astronomy The Space Telescope Science Institute offers pictures taken by the Hubble Space Telescope and other information on astronomy The Planetary Society is an organization that promotes exploration of the solar system. Its Website offers n

10、ews about current and prospective exploratory activities WBDBs about automobiles E is primarily a DB for publishing information about automobiles (although it also maintains a forum for exchanges of information and opinions) National Highway Traffic Safety Administration; its name explains it Insura

11、nce Institute for Highway Safety; its name explains it WBDBs for library and information science American Society for Information Science and Technology provides both information and links Association of Information Management Professionals (formerly, Association of Records Managers and Administrato

12、rs) provides both information and links,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Used for Publishing (contd),WBDBs for library and information science (contd) American Library Association main page ALA Resource

13、s for Parents, Teens and Kids provides links, in itself a form of publishing information* Libraries, Children & the Internet Questions & Answers provides both information and links* Teen Hoopla: An Internet Guide for Teens provides both information and links* Music Library Association provides both

14、information and links National Archives and Records Administration provides Access to Archival Databases, a research tool that makes a selection of the Archives most popular electronic records available to the public over the Internet Society of American Archivists provides both information and link

15、s Special Libraries Association provides both information and links Texas Library Association provides both information and links WBDBs on various subjects Consumer Reports Online provides ratings of goods and services, along with general advice on personal finance and product safety D provides acce

16、ss to the Dilbert comic strip Flags of the World is a WBDB about vexillology, the study of flags,*I am indebted to Ms. E. Joanmarie Marks for suggesting these sites.,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Use

17、d for Publishing (contd),WBDBs on various subjects (contd) offers access to the Frank and Earnest comic strip (with some of the worlds best puns) Hoaxbusters, “a public service of the CIAC and the U.S. Department of Energy“ exposes Internet hoaxes Iceland offers a wide variety of information about

18、Iceland InternetN provides news about the Internet, especially about commercial activities Scientific American offers information on science and access to experts in many scientific fields The Texas Records and Information Locator (TRAIL), of the Texas State Library, provides access to Texas state a

19、gencies and information sources. The U.S. Postal Service Rate Calculator enables you to calculate the postage required on letters and packages, both domestically and internationally. WBDBs on zoology University of Michigan Zoology Museum; its name explains it World Lecture HallZoology, UT-Austin pro

20、vides links to lectures, pictures, and divers sources of information on zoology,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Used for Publishing (contd),Other kinds of WBDBs whose primary purpose can be viewed as p

21、ublishing (after finding) information include search engines and online public-access catalogs Web-Search Engines maintain enormous DBs about the contents of Websites. Some examples: AltaVista Advanced Search Cest Trouv specializes in information in French Google Infobel and InfoSpace offer director

22、y information for people and businesses InfoSel offers search capabilities and news about Mexico and other parts of Latin America Northern Light S specializes in information in German Yahoo!,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Informat

23、ion Professions,WBDBs Used for Publishing (contd),Many libraries provide online access to their holdings via online public-access catalogs (OPACs). Clearly, OPACs are WBDBs. Some examples: The Austin Public Library Catalog The Catlogo de la Biblioteca Daniel Coso Villegas of El Colegio de Mxico Note

24、: This appears to be inaccessible with Netscape; use Internet Explorer. The Catlogo de Recursos de Informacin del Centro de Informacin-Biblioteca of the Instituto Tecnolgico y de Estudios Superiores de Monterrey (ITESM) The Catalogue BN-OPALE-PLUS of the Bibliothque Nationale Franaise. (After you re

25、ach the hyperlinked page, click on “Connexion au catalogue“. You should experiment with both the Recherche Simple and the Recherche Combine.) The Catalogue of the National Library of Australia The Harvard OnLine Library Information System (HOLLIS) of Harvard University The Library of Congress Online

26、 Catalog The OPACs of the University of California, Berkeley (GLADIS) and the University of California System (MELVYL) are both available via Library Online Catalog Systems The UTNetCat of the UT-Austin General Libraries I recommend that you visit all these online catalogs, do a search in each, and

27、compare the techniques that the catalogs offer and the results they yield. You will find interesting similarities and interesting differences.,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Used for Sharing Data,Foru

28、ms and Chat Rooms typify the WBDBs that are using for sharing data and information (and often misinformation). These uses are characterized by a two-way flow of information and data between the user and the WBDB, with the user typically supplying a substantial part of the flow. Some examples: CSICOP

29、 Chat Room, of the Committee for the Scientific Investigation of Claims of the Paranormal E Town Hall Community, “where smart car shoppers talk about cars, trucks and related consumer issues“ (the forum of E) Straight Dope Message Board, a forum for discussing topics related to Cecil Adamss syndicat

30、ed column, “The Straight Dope“ Teens Chat and Hang-Out Home Page, a chat room for teenagers ThirdAge, a forum for seniors to “meet & talk“ Upper Valley Materials Exchange, which “links businesses and community members who have surplus furniture, supplies, materials, equipment, etc. with schools (and

31、 other non-profits) in the Upper Connecticut Valley that have a use for them“ And, of course, any of the 59,000+ Usenet Groups can be regarded as a WBDB for sharing data (or at least opinions) and, lamentably often, for solicitations from businesses and services, pornography, etc.,School of Informat

32、ion - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Used for E-Commerce,As you are undoubtedly already aware, an enormous number of Websites are devoted to commercial activities, also characterized by a two-way flow of information and data

33、 between the user and the WBDB, with the user supplying only a limited part of the flow. As examples, we can mention four Websites that deal with books, both new and second-hand: A A BarnesandN P Note: Each of the above sites is slightly different from the others. You should compare each of them aga

34、inst the others with respect to their design, organization, and means of obtaining information from their users.,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,WBDBs Used to Drive Websites,Some WBDBs serve to keep Websites

35、 constantly up-to-date with current information. A few examples: CNBC.com, financial news from National Broadcasting Company CNN.com, general news from Cable News Network (CNN) CNNFN.com, financial news from CNN Note: I recommend your comparing CNBC and CNNFN. Though they target exactly the same aud

36、ience, their designs and organization are somewhat different. Greenwich provides the exact time (at the moment you open its Webpage), along with information about time-keeping The current weather in any of 10,000 cities is available from CNN Online: e.g., click here, Austin, for the weather in Austi

37、n W, the Web version of the Weather Channel on cable television, provides a variety of weather information Note: Again I recommend your comparing CNNs and the Weather Channels displays of local weather information.,School of Information - The University of Texas at Austin LIS 386.13, Information Tec

38、hnologies & the Information Professions,Techniques for Developing and Maintaining WBDBs,The WBDBs discussed in the foregoing slides have to be developed and maintained. The methods involved in doing so can be highly technical, so we shall merely sketch herein some general ideas about these methods.

39、Underlying all WBDBs is a relational database-management system (RDBMS), together with one or more relational databases (RDBs) that actually contain the data or information of interest A Webpage defined in HTML or Dynamic HTML (DHTML) controls the visual display that the user of the WBDB sees. An in

40、terface (1) receives information from the user and passes it to the RDBMS, (2) extracts information from the RDB (with the assistance of the RDBMS), and (3) provides the information to the Webpage, whose HTML or DHTML structure makes the information visible.,School of Information - The University of

41、 Texas at Austin LIS 386.13, Information Technologies & the Information Professions,Techniques for Developing and Maintaining WBDBs (contd),RDBMSs used for WBDBs Although Microsoft Access 97 (and later versions) offer built-in support for WBDBs, the limitations of MS Access restrict it to Websites t

42、hat experience small levels of use (no more than a few simultaneous users). Large and heavily used WBDBs typically use high-level RDBMSs such as IBM DB2, Informix, Microsoft SQL Server, Oracle, and Sybase. A substantial majority of such sites use Oracle.,School of Information - The University of Tex

43、as at Austin LIS 386.13, Information Technologies & the Information Professions,Techniques for Developing and Maintaining WBDBs (contd),The interfaces used for WBDBs fall into two broad classes Interfaces intended for a specific application and written in a scripting language that conforms to Common

44、 Gateway Interface (GCI) standards A script is a set of programming-language statements, typically (but not necessarily) short and used to accomplish certain actions on the Internet Languages used in scripts include C, C+, Java, Perl, and Visual Basic for Applications Interfaces developed commercial

45、ly for a certain class of applications Commercial interfaces include those of Oracle, SAP, and Siebel.,School of Information - The University of Texas at Austin LIS 386.13, Information Technologies & the Information Professions,Techniques for Developing and Maintaining WBDBs (contd),A popular tool f

46、or aiding in the development of CGI scripts is ColdFusion. You can think of ColdFusions role in working with CGI scripts as analogous to that of Dreamweaver and Microsoft FrontPage in aiding the preparation of HTML-formatted pages. P. Mohseni (1996, p. 238) describes ColdFusion as having the capabil

47、ities to “Insert and update records in database tables with HTML forms “Submit database queries that can then be used to dynamically generate Web pages “Intermix the results of queries with HTML tags and text for complete control over how data is displayed and formatted “Track users and customize th

48、eir view of Web pages by using information about their browser, location, or other preferences “Use advanced data input and reporting features “Validate form field entries as integer, floating point, date or numeric range,School of Information - The University of Texas at Austin LIS 386.13, Informat

49、ion Technologies & the Information Professions,Techniques for Developing and Maintaining WBDBs (contd),ColdFusion capabilities (contd) “Make conditional statements (if . . . else branching) to dynamically customize output returned to users and decisions about queries submitted to the database “Embed

50、 SQL statements in templates to specify queries. SQL statements may be dynamically customized using data from from submissions, URL query strings, and CGI environment variables, as well as the results returned from other queries “Execute multiple SQL queries and send SQL queries to multiple databases for each client request “Support Java and JavaScripts “Support Netscape cookies for state control“,