我正在为客户端/服务器应用程序中的“客户端”类实现异步命令模式。我之前进行过一些套接字编码，喜欢它们在Socket/SocketAsyncEventArgs类中使用的新的异步模式。
我的异步方法是这样的：
如果您需要更多详细信息，请看这里。这与使用SocketAsyncEventArgs类类似，但我的类名为SomeCmd。
与 Socket 类一样，如果您需要与回调方法 (在本例中为 SomeCmd_OnCompleted) 协调，则可以使用 ExecuteAsync 的返回值来确定操作是否挂起 (true) 或操作是否同步完成。
以下是我基础类的大幅简化版，您可以看到它的工作原理：
我的异步方法是这样的：
public bool ExecuteAsync(Command cmd);如果执行挂起，则返回true，如果同步完成，则返回false。我的问题是：即使出现异常，我是否应该始终调用回调（cmd.OnCompleted）？还是应该直接从ExecuteAsync抛出异常？如果您需要更多详细信息，请看这里。这与使用SocketAsyncEventArgs类类似，但我的类名为SomeCmd。
SomeCmd cmd = new SomeCmd(23, 14, 10, "hike!");
cmd.OnCompleted += this.SomeCmd_OnCompleted;
this.ConnectionToServer.ExecuteAsync(cmd);
与 Socket 类一样，如果您需要与回调方法 (在本例中为 SomeCmd_OnCompleted) 协调，则可以使用 ExecuteAsync 的返回值来确定操作是否挂起 (true) 或操作是否同步完成。
SomeCmd cmd = new SomeCmd(23, 14, 10, "hike!");
cmd.OnCompleted += this.SomeCmd_OnCompleted;
if( this.ConnectionToServer.ExecuteAsync(cmd) )
{
Monitor.Wait( this.WillBePulsedBy_SomeCmd_OnCompleted );
}
以下是我基础类的大幅简化版，您可以看到它的工作原理：
class Connection
{
public bool ExecuteAsync(Command cmd)
{
/// CONSIDER: If you don't catch every exception here
/// then every caller of this method must have 2 sets of
/// exception handling:
/// One in the handler of Command.OnCompleted and one where ExecuteAsync
/// is called.
try
{
/// Some possible exceptions here:
/// 1) remote is disposed. happens when the other side disconnects (WCF).
/// 2) I do something wrong in TrackCommand (a bug that I want to fix!)
this.TrackCommand(cmd);
remote.ServerExecuteAsync( cmd.GetRequest() );
return true;
}
catch(Exception ex)
{
/// Command completing synchronously.
cmd.Completed(ex, true);
return false;
}
}
/// <summary>This is what gets called by some magic when the server returns a response.</summary>
internal CommandExecuteReturn(CommandResponse response)
{
Command cmd = this.GetTrackedCommand(response.RequestId);
/// Command completing asynchronously.
cmd.Completed(response, false);
}
private IServer remote;
}
abstract class Command: EventArgs
{
internal void Completed(Exception ex, bool synchronously)
{
this.Exception = ex;
this.CompletedSynchronously = synchronously;
if( this.OnCompleted != null )
{
this.OnCompleted(this);
}
}
internal void Completed(CommandResponse response, bool synchronously)
{
this.Response = response;
this.Completed(response.ExceptionFromServer, synchronously)
}
public bool CompletedSynchronously{ get; private set; }
public event EventHandler<Command> OnCompleted;
public Exception Exception{ get; private set; }
internal protected abstract CommandRequest GetRequest();
}