Desk top aplications use an event driven i/o cycle

Web applications use a request-response i/o cycle

1. Client web browser requests a page from a server using HTTP protocol
2. Server builds response in HTML code from files and programs
3. Server returns response to client
4. Client displays the HTML in appropriate format

HTML is a page description or text markup language

• It is not a programming language
• It doesn't support variables or any sort of dynamic information

Adding dynamic information to the request-response cycle

The WOAdaptor is the link between the HTTP request-response cycle and your object-oriented web application

CGI adaptor provides interface to any standard HTTP server

Server specific adaptors are more efficient, e.g. Netscape API

WOApplications modify the request-respone i/o cycle

1. Client web browser - requests a page from a server using HTTP protocol
2. HTTP server - sends the request to the WOAdaptor
3. WOAdaptor - packages the request into a WORequest object and sends it to the WOApplication
4. WOApplication - replaces the <WEBOBJECTS> tag in the HTML with HTML to layout the dynamic elements on the page
5. WOApplication - returns a WOResponse object to the WOAdaptor
6. WOAdaptor - extracts the HTTP response and sends it to the HTTP Server
7. HTTP Server - sends HTML page to client
   

Demo : Building a WebObjects Application ( Download )