Question

我使用的是SignalR 2.2.1，这是NuGet的最新版本。我反对使用dynamic，因此总是首选强类型。

我的项目有两个“客户类”，因此有两个中心：

ChatClient + ChatHub : Hub<IChatClient>，它们是交换聊天应用程序消息的客户端。
AdminClient + AdminHub : Hub<IAdminClient>，具有特殊管理权限的客户

在AdminHub我希望调用ChatHub的方法，例如从数据库加载邮件并将其广播到ChatHub的所有用户：

这是我的逻辑（缩写）：

public interface IChatClient {

    void ReceiveMessage(String message);
}

public class AdminHub : Hub<IAdminClient> {

    // this method is called from the Admin client
    public void ShowMotdToRandomUser() {

        String message = GetMessageOfTheDayFromDatabase( ... );

        // get the Chat hub:
        DefaultHubManager defaultHubs = new DefaultHubManager( GlobalHost.DependencyResolver );
        ChatHub chatHub = defaultHubs.ResolveHub( "Chat" ) as ChatHub;
        chatHub.Context = this.Context; // because chatHub.Context == null

        chatHub.InternalSendMessageToRandomUser( message );
    }
}


public class ChatHub : Hub<IChatClient> {

    // this is a normal hub method that chat hub clients call
    public void SendMessage(String message) {

        this.Clients.All.ReceiveMessage( message );
    }

    // this is the special method called from AdminHub:
    internal void InternalSendMessageToRandomUser(String message) {

        String connectionId = GetRandomConnectionId( ... ); // the Hub stores all connectionIds from OnConnected to static state
        this.Client( connectionId ).ReceiveMessage( message );
    }
}

然而，在IChatClient.ReceiveMessage：

的调用中失败了

NullReferenceException {"Object reference not set to an instance of an object."}
at Microsoft.AspNet.SignalR.Hubs.SignalProxy.Invoke(String method, Object[] args)
at Microsoft.AspNet.SignalR.Hubs.TypedClientBuilder.IChatHubClientImpl.ReceiveMessage(String )
at MyProject.ChatHub.InternalSendMessageToRandomUser(String message)
at MyProject.AdminHub.ShowMotdToRandomUser(String message)
at lambda_method(Closure , IHub , Object[] )
at Microsoft.AspNet.SignalR.Hubs.HubMethodDispatcher.<>c__DisplayClass10_0.<WrapVoidAction>b__0(IHub hub, Object[] parameters)
at Microsoft.AspNet.SignalR.Hubs.HubMethodDispatcher.Execute(IHub hub, Object[] parameters)
at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.Incoming(IHubIncomingInvokerContext context)

SignalR 2.2.1中的跨中心调用 - DefaultHubManager使用null HubCallerContext获取Hub

0 个答案: