AJAX Daniel Daugherty [email protected]

What is AJAX

Asynchronous JavaScript and XML Other terms to know  XMLHttpRequest  JSON

What is AJAX used for

Data retrivial Send data to the server for processing.

Form Validation Anything you might load a new page for.

 It is possible to build “One Page” Ajax Applications.

What is AJAX NOT

AJAX is NOT DHTML

AJAX is commonly used allong with DHTML to provide enhanced user interface. But they are 2 separate things.

How to implement AJAX Write XMLHttpRequest your self.

Use a AJAX Framework.

 Many many many many frameworks out there.  DWR for JAVA  AJAX.CFC + DWR.CFC for Coldfusion.

DWR Setup

Download DWR – http://getahead.ltd.uk/dwr/ Install DWR.jar in your J2EE server classpath.

Edit web.xml to add the DWR as a servlet.

Edit DWR.XML to list objects to be made available via AJAX.

AJAX.CFC /DWR.CFC

Unzip AJAX.zip into a folder in your web root. Edit DWR.XML to list objects to be made available via AJAX

How do I call DWR/AJAX.CFC

JS templates are needed engine.js util.js optional but recomeneded .

JAVA  dwr/interface/[JavascriptName].js

ColdFusion   ajax_js_stub.cfm?component=[JavascriptName] wddx.js

Demo

Security

Limit the type of things available via AJAX.

Java  Supports restriction with J2EE roles  Security Filter.

ColdFusion  Application.cfm or Application.CFC

 cflogin roles

Error Handling

Client Side  DWREngine.setWarningHandler()  DWREngine.setErrorHandler() Server Side  May need to adjust server side error trapping to be AJAX aware.

Debugging

Server side  LOG files are your friend. Client Side  Firefox Javascript Debugger  Firebugs  HTTP Trace utility  Javascript alert()  DDumper.js - Comes with AJAX.CFC