通用主机中的同步发送/回复

Question

我正在尝试使用通用主机 Windows 服务的处理程序函数的同步发送/回复，如下所示。但我认为NServiceBus只有在完成句柄功能后（在当前事务完成期间）才会发送消息。因此下面的代码将挂在“synchronousHandle.AsyncWaitHandle.WaitOne()”中。

这里最好的方法应该是什么？你能指导我吗...

    Handler constructer

    ConstructorFunction(bus)
    {
                    Bus = bus
    }

    code in the handle function. 
    // sent the message to the bus and wait for the reply

    IMessage response = null;

    var synchronousHandle = Bus.Send(service2queue, requestMessage)
                                            .Register(
                                            (AsyncCallback)delegate(IAsyncResult asyncResult)
                                            {
                                                // Callback block for reply message
                                                // Reply message received
                                                NServiceBus.CompletionResult completionResult = asyncResult.AsyncState as NServiceBus.CompletionResult;
                                                if (completionResult != null && completionResult.Messages.Length > 0)
                                                {
                                                    // Always expecting one IMessage as reply
                                                    response = completionResult.Messages[0];
                                                }
                                            },
                                            null);


// block the current thread till the reply received.
synchronousHandle.AsyncWaitHandle.WaitOne();

谢谢， 阿贾伊

Answer 1

当事情不应该做时，nservicebus 会尝试让事情变得尽可能困难。

来自 nservicebus 文档：

Bus.Send(request).Register(asyncCallback, state)

Callback only fires on first response, then is cleaned up to prevent memory leaks. 
Doesn’t survive restarts – not suitable for server-side

假设您位于服务器端（我在这里猜测是因为您向我们展示了一个消息处理程序）我会考虑重新设计。

service1 gets a notification about messageA
service1 sends message requestMessage to service2
service2 replies with message responseMessage to service1
service1 handles responseMessage and continues processing

如果您想在继续处理之前等待 service1 中的多条消息，请尝试考虑实现 sagas。