如何在SignalR客户端中使用async / await与hub.On

我有一个与SignalR Hub（服务器）通信的.Net Windows服务（客户端）。 大多数客户端方法都需要时间来完成。 当从服务器接收调用时，我如何（或者我需要）包装目标方法/ hub.On以避免警告：

“因为没有等待这个调用，所以当前方法的执行在调用完成之前继续。考虑将await运算符应用于调用的结果”

在客户端上，这是启动/设置代码的示例：

IHubProxy _hub string hubUrl = @"http://localhost/"; var connection = new HubConnection(hubUrl, hubParams); _hub = connection.CreateHubProxy("MyHub"); await connection.Start(); _hub.On("SendMessageToClient", i => OnMessageFromServer(i.Id, i.Message)); _hub.On("SendCommandToClient", i => OnCommandFromServer(i.Id, i.Command)); 

同样在客户端上，这是方法的示例：

 public static async Task OnMessageFromServer(string Id, string message) { try { var result = await processMessage(message); //long running task } catch (Exception ex) { throw new Exception("There was an error processing the message: ", ex); } return result; } public static async Task OnCommandFromServer(string Id, string command) { try { var result = await processCommand(command); //long running task } catch (Exception ex) { throw new Exception("There was an error processing the message: ", ex); } return result; } 

最终，我认为_hub.On正在注册回调，而不是来自服务器的实际执行（调用）。 我想我需要进入实际执行的中间，等待On [X] FromServer的结果并返回结果。

*************更新后的示例和更正后的代码*********************

 IHubProxy _hub string hubUrl = @"http://localhost/"; var connection = new HubConnection(hubUrl, hubParams); _hub = connection.CreateHubProxy("MyHub"); await connection.Start(); //original //_hub.On("SendMessageToClient", i => OnMessageFromServer(i.Id, i.Message)); //_hub.On("SendCommandToClient", i => OnCommandFromServer(i.Id, i.Command)); //new async _hub.On("SendMessageToClient", async (i) => await OnMessageFromServer(i.Id, i.Message)); _hub.On("SendCommandToClient", async (i) => await OnCommandFromServer(i.Id, i.Message)); //expanding to multiple parameters _hub.On<Message, List, bool, int>("SendComplexParamsToClient", async (p1, p2, p3, p4) => await OnComplexParamsFromServer(p1.Id, p1.Message, p2, p3, p4)); 

然后目标方法签名就像

 public static async Task OnComplexParamsFromServer(string id, string message, List incommingMessages, bool eatMessages, int repeat) { try { var result = await processCommand(message); //long running task if (result) { // eat up your incoming parameters } } catch (Exception ex) { throw new Exception("There was an error processing the message: ", ex); } return result; } 

感谢@AgentFire的快速反应!!!

Answer 1

这是一个无法等待的模式，使用它像这样：

 _hub.On("SendMessageToClient", async i => await OnMessageFromServer(i.Id, i.Message))