postback and callback

postback:
In the default model for ASP.NET Web pages, the user interacts with a page and clicks a button or performs some other action that results in a postback. The page and its controls are re-created, the page code runs on the server, and a new version of the page is rendered to the browser.

callback:
In a client callback, a client script function sends a request to an ASP.NET Web page. The Web page runs a modified version of its normal life cycle — the page is initiated and its controls and other members are created, and then a specially marked method is invoked. The method performs the processing that you have coded and then returns a value to the browser that can be read by another client script function. Throughout this process, the page is live in the browser.  

2006-04-24 22:06 by 心只有你

@ James Chen

看了你的解答我清楚了很多，是不是IsPostBack为true时，页面有任何变化都需要重新生成，给人刷新的感觉。而IsCallBack为true时，感觉只是客户端脚本在运行，虽然页面有变化，但是没有刷新的感觉。不过写客户端脚本是真的是一件很繁人的事情！！！
你看过Atlas吗？那个框架提供了一大堆的控件来实现Ajax一样的感觉，是不是也用到了Page的IsCallBack？

2006-04-24 22:34 by James Chen

你说的不错。PostBack方式刷新整个页面，CallBack方式不刷新整个页面。但是CallBack不能等同于Ajax，据说两者的实现原理不同。CallBack只能传送string类型的参数，而Ajax使用的是httprequest+xml的机制。Atlas我没看过，但它是实实在在的.NET环境下的Ajax库。没看的原因一是因为苏鹏的Ajax Webcast里还没讲到它，二是没听到它是否正式release了，呵呵。
原文链接:http://www.cnblogs.com/dkhero/archive/2006/04/19/379188.html