A New Approach to web applications - AJAX
The standard and well-known method for user interaction with web-based applications involves the user entering information (e.g. filling out a form), submitting that information to the server, and awaiting a page refresh or redirect to return the response from the server. This is at times frustrating for the user, besides being rather different to the 'desktop' style of user interface with which (s)he may be more familiar.
Ajax (Asynchronous JavaScript and XML) is a technique for submitting server requests 'in the background' and returning information from the server to the user without the necessity of waiting for a page load. i.e. Ajax allow web pages to be updated with new information from the server, without the user having to wait for a page refresh, providing a better experience for the user.
The following is an outline of the sequence of events when using AJAX:
· Web page is rendered
· A trigger executes a JavaScript function call (i.e. onKeyUp, button click, setTimeout, page load, etc.)
· JavaScript instantiates an XML HTTP object
· XML HTTP object calls a remote page
· Remote Page transforms an XML structure using XSLT and returns the result
· JavaScript accepts the results and applies it to the page
· No page reload, just magical dynamic data
XML HTTP allows code to connect to a remote location and perform GET and POST requests asynchronously.
*** XML HTTP- Primary communication broker
The AJAX Engine- Which calls web services asynchronously
Benefits of AJAX
ü Better Performance and Efficiency - small amount of data is transferred from the server and low band width network.
ü More Responsive Interfaces - the improved performance leads to much more responsive application.
ü Reduced or Eliminated "Waiting" Time – in AJAX-based applications only the relevant page elements are updates, with the rest of the page remaining unchanged.
ü Users Can Work with the Rest of the Page – applications allow you to continue working with the rest of the page, while data is being transferred in the background.
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