Clicks & Notes

21 February 2005

“Ajax” and the new breed of web applications

adaptive path - ajax: a new approach to web applications

  • “Ajax” (shorthand for “Asynchronous JavaScript + XML") is a way to make web applications more responsive to user interaction
  • traditional web applications rely on communication between a user and a web server via HTTP, which result in a “start-stop-start-stop” type of interaction:
    • user sends a request to the server
    • the server processes the request
    • the server returns a(nother) web page back to the user
    • repeat…
  • an Ajax “engine"– written in JavaScript, and loaded at the start of a user session – can instead act as an intermediary between the user and server:

    Any response to a user action that doesn’t require a trip back to the server — such as simple data validation, editing data in memory, and even some navigation — the engine handles on its own

    If the engine needs something from the server in order to respond — if it’s submitting data for processing, loading additional interface code, or retrieving new data — the engine makes those requests asynchronously, usually using XML, without stalling a user’s interaction with the application.

  • Ajax is not a new technology in and of itself; it incorporates existing web technologies:
    • standards-based presentation using XHTML and CSS;
    • dynamic display and interaction using the Document Object Model;
    • data interchange and manipulation using XML and XSLT;
    • asynchronous data retrieval using XMLHttpRequest;
    • and JavaScript binding everything together.
  • current online applications using Ajax include the various Google products, Flickr and
⇒ Filed under:  by jen @ 11:53 pm


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© Jennifer Vetterli, 2005