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This overview delves into the requirements, modes of delivering databases via the web, relevant technologies, and evaluation of Web DBMS. It discusses dynamic web pages, real-time querying mechanisms, and differentiating two-tier and three-tier Web-DBMS structures.
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BBIT423/CISY423ADBMS Internet/Web Databases 31.03.2011
Overview (objective of discussions) • Requirements for a Web DBMS • Modes of delivering databases via the web • Relevant technologies • Evaluation
Introduction • Web DBMS initially about dynamic web pages • Various ways to deliver database services over the web • Periodically dump a database table to an HTML file and make the HTML file available on the web • Provide a mechanism to query the database in real time and format the results in HTML. • Provide the web user with a form or other means to invoke a query on the database in real time. Results are formatted in HTML and returned to the user's browser.
Server-side validation • Database access • User interface • Main business and data processing logic
May differentiate two tier and three tier of Web- DBMS • Your examples:
A note on Web Application Architectures • Model • A model is meant to serve as a computational approximation or abstraction of some real world process or system (the DBMS) • View • Visual feedback / formatting to the users (HTML) • Controller • Interprets user inputs from the user and maps these user actions into commands that are sent to the model and/or view to effect the appropriate change
Web DBMS technologies • Web server • Web server extensions (scripting engines) • + client side scripting • Protocols: HTTP • Languages: HTML, XML
There are two main ways to carry out dynamic real-time queries from the web: • Using traditional HTML forms, information is passed to a CGI script that formats the query and submits it to the DBMS. • Results are returned to the CGI script which then formats the output in HTML
There are two main ways to carry out dynamic real-time queries from the web: • Using traditional HTML forms … • Many DBMS now have the web server built in (or closely tied) to the database. e.g., Oracle Web Applications Server. • Stored procedures in the DBMS are used to accept input from HTML forms, perform the appropriate query and then format the results in HTML
Requirements for Database services over the Web (Interface) • Your database (Access, MySQL, Oracle etc) • A Web server with appropriate DBMS • A way of connecting the two (Middleware) • Scripting technologies to process the interaction
We need a DB first • Case of telephone extensions at KEMU • You are required to provide a web based (intranet) access to the telephone directory at KEMU • DB design • Discussion of findings and evaluated for all
Web-DBMS Advantages • Simplicity • Platform Independence (Cross-Platform Support) • GUI • Standardization • Transparent Network Access • Scalable Deployment
Web-DBMS Disadvantages • Security • Reliability • Bandwidth • Costs – human resources and project management • Limited functionalities • HTTP is a “stateless” protocol - does not retain information between transactions • etc
Next week • Revision for the exam • Come with your questions/points of clarification • Thanks