15 Chapter 15 Web Database Development Database Systems: Design, Implementation, and Management, Fifth Edition, Rob and Coronel

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 2 In this chapter, you will learn: How Internet databases are typically used About the architecture of Web-to-database middleware How Web-to-database middleware (ColdFusion) is used to integrate databases with the Internet What special considerations govern Web database development

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 3 Web Database Connectivity Allows rapid response to competitive pressures –New services –New products Customer support enhanced Fast effective information dissemination –Universal access –Local –Around the globe

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 4 Typical Uses of Internet Table 15.2

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 5 Characteristics/Benefits of Internet Technology Hardware & software independence –Cost savings –Uses existing equipment –Platform independence and portability –No need for multiple platform development Common simple user interface –Reduced training –Reduced support

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 6 Characteristics/Benefits of Internet Technology (con’t.) Location Independence –Global access through Internet –Reduced costs for dedicated connections Rapid development at manageable costs –Development tools –Low entry costs –Available software & access tools

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 7 Web-to-Database Middleware Server-side extension –Interacts directly with Web server –Handles specific requests –Also known as Web-to-database middleware –Examples ColdFusion CGI API

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 8 Web-to-Database Middleware Figure 15.1

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 9 Web Server Interfaces Common Gateway Interface (CGI) –Uses script files to connect to database –Perl, C++, VB Application Programming Interface (API) –Newer and more efficient –Uses DLLs –Memory resident and faster –Well known APIs Netscape (NSAPI) Internet Server API from Microsoft (ISAPI) WebSite API from O’Reilly (WSAPI)

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 10 API and CGI Web Server Interfaces Figure 15.2

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 11 Web-to-Database Middleware Connection Methods Native SQL access middleware Use services of Open Database Connectivity (ODBC) Use Object Linking and Embedding Database (OLE DB) interface with Windows ODBC most common

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 12 ODBC to Access Databases Figure 15.3

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 13 Web-to-Database Middleware Uses ODBC to Access Databases Figure 15.4

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 14 Web Browser Located on the client computer End user Web interface Interprets HTML code received from Web server Presents page components in a standard way Client-side extensions –Plug-ins –Java and JavaScript –ActiveX and VBScript

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 15 ColdFusion Web application server Uses –Connect and query database from Web page –Present database data in a Web page –Create dynamic Web search pages –Create Web pages to insert, update, and delete data –Define required and optional relationships –Define required and optional form fields –Enforce referential integrity in form fields –Use simple and nested queries to represent business rules

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 16 How ColdFusion Works Figure 15.5

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 17 How ColdFusion Works Server-side markup language –HTML extensions –ColdFusion Markup Language (CFML) Executed in interpreter mode Contain HTML, CFML May contain Java, JavaScript, or VBScript Client browser requests.cfm page from Web Server –ColdFusion application server executes.cfm script –Sends resulting output in HTML to Web Server –Web server sends to client browser

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 18 ColdFusion Tags CFQuery –Queries a database CFOutput –Displays data returned by query CFTable –Displays data in Tabular format

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 19 ColdFusion Dynamic Query Create script to generate form with criteria used in database search Create script to execute query and display results –Uses ColdFusion tags –Uses HTML

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 20 The Web as a Stateless System Web server does not know status of any client at any given time Request-reply model of communication Browser concerned only with current page Data processing requires additional software –Java, JavaScript, VBScript

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 21 INSERTs and UPDATEs with ColdFusion CFINSERT Tag –Adds records to database –Parameters DATASOURCE TABLENAME CFUPDATE Tag –Updates selected database contents –Parameters DATASOURCE TABLENAME

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 22 DELETEs with ColdFusion CFQUERY Tag –Uses SQL DELETE Statement –Parameters DATASOURCE TABLENAME

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 23 Internet Database: Special Considerations Involve more than just database-enabled Web applications Issues important to corporate databases –Data security –Transaction management –Client-side data validation –Operational and management challenges Database applications development most affected by Internet

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 24 Supported Data Types Integrated data from multiple sources –Word-processor documents –Pictures –Sounds –Movies Methods for storing and extracting data objects Overhead created by storage Client browser support of object being accessed Size of database considering multimedia and other data

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 25 Data Security Web Server Level –Secure transactions using encryption –TCP/IP protocol level –Firewalls RMDBS Vendors –Login authentication –Restrict access to particular SQL commands Web-to-database middleware –End user restrictions –Designer created algorithms Must support e-commerce applications

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 26 Transaction Management Concept is foreign to Web Dilemma created by request-reply model –Web cannot maintain open line between client and database –Recovery requires client maintain open communications Designers must ensure proper transaction management support at database server level ColdFusion uses CFTRANSACTION tag for transaction management support

15 Database Systems: Design, Implementation, & Management, 5 th Edition, Rob & Coronel 27 Denormalization Web forms –Cannot use multiple data entry lines –1:M relationships problematic Solutions –Web programming languages –Java, JavaScript, VBScript