Web Database Development

1
Chapter 15

• Web Database Development
• Database Systems Design, Implementation, and
  Management, Fifth Edition, Rob and 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

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

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Typical Uses of Internet
Table 15.2
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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

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Characteristics/Benefits of Internet Technology
(cont.)

• 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

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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

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Web-to-Database Middleware
Figure 15.1
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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 OReilly (WSAPI)

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API and CGI Web Server Interfaces
Figure 15.2
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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

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ODBC to Access Databases
Figure 15.3
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Web-to-Database Middleware Uses ODBC to Access
Databases
Figure 15.4
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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

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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

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How ColdFusion Works
Figure 15.5
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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

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ColdFusion Tags

• CFQuery
• Queries a database
• CFOutput
• Displays data returned by query
• CFTable
• Displays data in Tabular format

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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

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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

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INSERTs and UPDATEs with ColdFusion

• CFINSERT Tag
• Adds records to database
• Parameters
• DATASOURCE
• TABLENAME
• CFUPDATE Tag
• Updates selected database contents
• Parameters
• DATASOURCE
• TABLENAME

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DELETEs with ColdFusion

• CFQUERY Tag
• Uses SQL DELETE Statement
• Parameters
• DATASOURCE
• TABLENAME

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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

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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

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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

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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

27
Denormalization

• Web forms
• Cannot use multiple data entry lines
• 1M relationships problematic
• Solutions
• Web programming languages
• Java, JavaScript, VBScript