Week 7 Lecture

Web Database Development

Samuel Conn, Asst. Professor

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In this lecture, 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

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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 (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

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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 O’Reilly (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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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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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

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Denormalization

Web forms Cannot use multiple data entry

lines 1:M relationships problematic

Solutions Web programming languages Java, JavaScript, VBScript