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ASP.net中的服务器回调

[英]Server callbacks in ASP.net

原文 2009-12-26 17:16:19 2 1 asp.net

What is the correct way to implement server callbacks in ASP.net to update a control? 在ASP.net中实现服务器回调以更新控件的正确方法是什么？ I know all about AJAX and async client calls to server but what about this scenario: 我了解有关服务器的AJAX和异步客户端调用的全部知识，但这种情况如何：

You display a treeview (server control) with a list of items to the user. 您将显示一个树视图（服务器控件），其中包含用户列表。 You have a server process running which checks a queue. 您有一个正在运行的服务器进程正在检查队列。 When an item gets added to the queue it should update the tree control. 将项目添加到队列时，它应该更新树控件。 How? 怎么样？ Sounds easy. 听起来很简单。 But seems ridiculously difficult in ASP.net. 但是在ASP.net中似乎非常困难。

1 个解决方案

The server cannot (generally) push content out to the client. 服务器无法（通常）将内容推送到客户端。 Web browsers operate in a disconnected environment - in order to simulate "push" behavior you have to have the client periodically poll the server. Web浏览器在断开连接的环境中运行-为了模拟“推送”行为，您必须让客户端定期轮询服务器。

The exception to this is if you can use a technology like Silverlight or Flash, which can maintain persistent duplex connections to the server independent of the browser. 例外情况是，如果您可以使用Silverlight或Flash之类的技术，该技术可以独立于浏览器维护与服务器的持久双工连接。

As far as I'm aware, most website that appear to dynamically "push" content out to the browser (eg. gmail, facebook chat, etc) are really polling periodically from the client. 据我所知，大多数似乎动态地将内容“推送”到浏览器（例如gmail，facebook聊天等）的网站实际上都是定期从客户端进行轮询。