Difference between callback and postback?

Posted on 2006-05-26
Last Modified: 2012-05-05

I guess callback is a new term introduced in .NET 2.0
Pls explain the difference between callback and postback?

Thanks & Regards
Question by:pradith
    LVL 19

    Accepted Solution

    Callbacks are HTTP requests called from the client browser using javascripts and the response are also intercepted by javascript.
    The essential difference between callbacks and postbacks is the absence of a full page reload in a callback.
    In a postback, the form data content is submitted as a POST request and the response returned is a complete HTML page.
    A postback request-response cycle results in page refresh, with callbacks, both requests and responses are handled with javascript, it is unnecessary to reload the whole page on a callback response, only additional or new content are added or replaced.

    Effectively, callbacks allows incremental changes to a page.

    Basically, callbacks are the basic principle for AJAX to work.

    LVL 4

    Expert Comment

    Max is absolutly right.

    Callbacks allow to refresh the page contents partially while page gets reloaded during postback.

    For IE , we can use XMLHttp object to implement callback.. Callback is related to the browser's behaviour.

    Author Comment

    Thank You
    LVL 19

    Expert Comment

    You are very welcome!


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