我想实现一个网络聊天。
后端是双 WCF 通道。双通道工作在控制台或winform中,
它实际上可以在网络上运行。我至少可以发送和接收消息。
作为我使用的基础这篇博文 http://blogs.claritycon.com/blog/2011/04/12/roll-your-own-mvc-3-long-polling-chat-site/这样,异步操作就完成了。
当我调试结果时,我看到消息已准备好发送到浏览器。
[AsyncTimeout(ChatServer.MaxWaitSeconds * 1020)] // timeout is a bit longer than the internal wait
public void IndexAsync()
{
ChatSession chatSession = this.GetChatSession();
if (chatSession != null)
{
this.AsyncManager.OutstandingOperations.Increment();
try
{
chatSession.CheckForMessagesAsync(msgs =>
{
this.AsyncManager.Parameters["response"] = new ChatResponse { Messages = msgs };
this.AsyncManager.OutstandingOperations.Decrement();
});
}
catch (Exception ex)
{
Logger.ErrorException("Failed to check for messages.", ex);
}
}
}
public ActionResult IndexCompleted(ChatResponse response)
{
try
{
if (response != null)
{
Logger.Debug("Async request completed. Number of messages: {0}", response.Messages.Count);
}
JsonResult retval = this.Json(response);
Logger.Debug("Rendered response: {0}", retval.);
return retval;
}
catch (Exception ex)
{
Logger.ErrorException("Failed rendering the response.", ex);
return this.Json(null);
}
}
但实际上什么也没发送。
检查 Fiddler,我看到了请求,但从未得到响应。
[SessionState(SessionStateBehavior.ReadOnly)]
public class ChatController : AsyncController
我还必须将 SessionStateBehaviour 设置为 Readonly,否则异步操作会阻塞整个页面。
编辑:
这是 CheckForMessagesAsync:
public void CheckForMessagesAsync(Action<List<ChatMessage>> onMessages)
{
if (onMessages == null)
throw new ArgumentNullException("onMessages");
Task task = Task.Factory.StartNew(state =>
{
List<ChatMessage> msgs = new List<ChatMessage>();
ManualResetEventSlim wait = new ManualResetEventSlim(false);
Action<List<ChatMessage>> callback = state as Action<List<ChatMessage>>;
if (callback != null)
{
IDisposable subscriber = m_messages.Subscribe(chatMessage =>
{
msgs.Add(chatMessage);
wait.Set();
});
bool success;
using (subscriber)
{
// Wait for the max seconds for a new msg
success = wait.Wait(TimeSpan.FromSeconds(ChatServer.MaxWaitSeconds));
}
if (success) this.SafeCallOnMessages(callback, msgs);
else this.SafeCallOnMessages(callback, null);
}
}, onMessages);
}
private void SafeCallOnMessages(Action<List<ChatMessage>> onMessages, List<ChatMessage> messages)
{
if (onMessages != null)
{
if (messages == null)
messages = new List<ChatMessage>();
try
{
onMessages(messages);
}
catch (Exception ex)
{
this.Logger.ErrorException("Failed to call OnMessages callback.", ex);
}
}
}
这与引用的博客文章中的想法相同
编辑2:
顺便说一句,当没有收到任何消息时,等待超时就会生效,响应就会返回。所以它似乎在某个地方崩溃了。知道如何记录这个吗?