Web Access to Databases

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Web Access to Databases

• Tom Whaley
• Department of Computer Science
• Washington and Lee University
• Part 1
• Overview of Web Access to Database

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Goal

• Create a simple database together with a suite of
  simple web pages that provide access to the
  database.

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How do we get there?
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The Plan where are we going?

• I. General Overview
• II. Web Forms
• III. VBScript and Active Server Pages
• IV. Web Access to Database

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Part I General Overview
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Why web access to database?

• Provides platform independent, remote access to
  the database
• Data viewing
• Data gathering

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Web Browsers and Servers

• Web browser - This is a program that runs on your
  local PC (client). It allows you to request web
  pages from an internet host.
• Web server - This is a program that runs on the
  internet host computer (server). It takes
  requests for web pages from clients and delivers
  the pages back to the client.

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HTML and HTTP

• HyperText Markup Language - Allows marking up a
  document with tags specifying appearance and
  structure.
• HyperText Transfer Protocol - Protocol used for
  browsers to communicate with web servers.
  Basically, this consists of requests from the
  browser and responses from the server.

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Typical HTTP Request
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Typical HTML Request

• Client Side (Browser)
• Issues request for HTML page
• Receives response HTML page
• Interprets HTML and creates web page
• Displays web page
• Work is done here

• Server Side
• Reads request from client
• Finds page on server
• Sends response page to client
• Essentially a file server

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Scripting Languages

• Scripting languages - Allow us to add capability
  to whats provided by HTML. Allow parts of the
  page to be built on the fly
• Client-side scripts - Script engine on client
  machine builds parts of page when page is loaded
  by browser (date is simple example). This is
  often used to validate user input before sending
  to server.
• Server-side scripts - Script engine on server
  builds parts of page before sending to client
  (database query results for example).

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Typical Server-Side Request
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Typical Server-Side Request

• Client Side (Browser)
• Issues request for HTML page
• Receives response HTML page
• Interprets HTML and creates web page
• Displays web page

• Server Side
• Reads request from client
• Finds page on server
• Interprets script code
• Does work dictated by this code (or has it done)
• Alters HTML file
• Sends response page to client

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Web Access of Database

• The database resides on the server.
• Web pages with scripts (or calls to scripts)
  allows the user to send database requests to the
  server.
• The server accesses the database to honor the
  requests.
• Results can be returned on an html page.
• Actions can take place on the database.

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So, what are the pieces we need?

• Browser software on user machines
• A machine for the server
• Web server software on server
• Database management system on server
• Scripting/programming language for accessing the
  database
• Drivers/interfaces for scripting language to
  access the database
• A book

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So, what are the pieces we use?

• Browser Netscape or Internet Explorer
• Server machine NT Server
• Web server Microsoft Internet Information Server
  (IIS)
• Includes ASP
• Database management system Access
• Scripting VBScript with ASP
• Database interface ActiveX Data Objects
• Books
• Beginning Active Server Pages 2.0, Francis, et.
  al., Wrox
• ASP in a Nutshell, Weissinger, OReilly

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