异步方法是否在单独的线程中运行？

Question

My silverlight application is calling a webservice method asynchronously as follows:

 gServer = new ServiceReference1.Service1SoapClient();

 gServer.Retrieve_DataSet_ListCompleted += new EventHandler<ServiceReference1.Retrieve_DataSet_ListCompletedEventArgs>(Retrieve_Data_List_Completed);

Does Retrieve_Data_List_Completed method run in a different thread?

Answer 1

The event handler will run in the thread that instantiated Gserver. The asynchronous bit is gServer beavering away gettimng the data on it's thread, when it's don it tells "your" thread it is.

Answer 2

No thread will be running waiting for the result. Async webservice calls are entirely threadless. Everything down to the socket read and write operations happens using async methods. The socket itself will queue the request to an IO completion port which is a Windows kernel primitive.

Only when the result is available your callback will be invoked on some random thread. But this thread did not need to be there all the time. It is taken from the thread-pool.