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Web Applications

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ActiveX and VBScript. 11/14/2002. TCSS445A Isabelle Bichindaritz. 15. The Web as ... Java, JavaScript, VBScript. 11/14/2002. TCSS445A Isabelle Bichindaritz. 16 ... – PowerPoint PPT presentation

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Title: Web Applications


1
Web Applications
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 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

4
Typical Uses of Internet
Table 15.2
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

6
Characteristics/Benefits of Internet Technology
  • 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

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
  • JSP, Servlet

8
Web-to-Database Middleware
Figure 15.1
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 OReilly (WSAPI)

10
API and CGI Web Server Interfaces
Figure 15.2
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

12
ODBC to Access Databases
Figure 15.3
13
Web-to-Database Middleware Uses ODBC to Access
Databases
Figure 15.4
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
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

16
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

17
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

18
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

19
Denormalization
  • Web forms
  • Cannot control data entry
  • 1M relationships problematic (not dynamic) (Ex
    invoice / invoice line)
  • Solutions
  • Web programming languages
  • Java, JavaScript, VBScript

20
JSPs
  • JSP tutorial http//java.sun.com/j2ee/tutorial/
    1_3-fcs/doc/JSPIntro.html
  • Bookstore example.

21
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