SignalR and Typed Objects

Question

I have a very basic self-hosted webservice using SignalR 2.x with the following configuration:

Server:

internal class WebService
{
    public void Configuration( IAppBuilder app )
    {
        var config = new HttpConfiguration { DependencyResolver = new ControllerResolver() };
        config.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
        config.Formatters.JsonFormatter.SerializerSettings.TypeNameHandling = TypeNameHandling.Objects;
        config.Routes.MapHttpRoute( "Default", "{controller}/{id}", new { id = RouteParameter.Optional } );
        app.UseWebApi( config );
        app.MapConnection<EventDispatcher>( "", new ConnectionConfiguration { EnableCrossDomain = true } );

        GlobalHost.DependencyResolver.Register(typeof(JsonSerializer), () => JsonSerializer.Create(new JsonSerializerSettings
                                            {
                                                TypeNameHandling = TypeNameHandling.All
                                            }));

        app.MapHubs();
    }
}

Server code to send a message:

public class Notifier
{
    static readonly IPersistentConnectionContext Context = GlobalHost.ConnectionManager.GetConnectionContext<EventDispatcher>();

    public static void NotifyAll( NotificationType type, object obj )
    {
        Context.Connection.Broadcast( ConstructEvent( type, obj ) );
    }

    public static object ConstructEvent( NotificationType type, object obj )
    {
        var notevent =  new { Event = type.ToString(), Data = obj };
        return notevent;
    }
}

Client:

void connect()
{
    var _eventHandler = new Connection(Address);
    _eventHandler.JsonSerializer.TypeNameHandling = TypeNameHandling.Objects;
    _eventHandler.Received += eventHandler_Received;
    _eventHandler.Start().Wait();
}

The web service nicely returns typed JSON, but the updates send by SignalR are plain JSON. Am I missing something here?

I tried your sample client and it sends Json Typed data=%7B%22%24type%22%3A%22%3C%3Ef__AnonymousType0%602%5B%5BSystem.Int32%2C+mscorlib%5D%2C%5BSystem.String%2C+mscorlib%5D%5D%2C+Microsoft.AspNet.SignalR.Client.Samples%22%2C%22type%22%3A1%2C%22value%22%3A%22first+message%22%7D — Gustavo Armenta
– Gustavo Armenta, Commented Jul 12, 2013 at 16:08
It turns out the problem is that I call the PersistentConnection through Notifier.NotifyAll() outside of the Controllers. For some reason it then uses the default JSonParser. I tried to set the TypeNameHandling inside the overrid Initializeof the PersistentConnection , but that does not have any effect. — dsfgsho
– dsfgsho, Commented Jul 16, 2013 at 16:07

dsfgsho · Accepted Answer · 2013-07-16 16:24:52Z

Although the whole setup is rather esoteric, here's the solution for those interested.

I think the problem was caused by making the GlobalHost.ConnectionManager.GetConnectionContext static. By doing this I think I created a PersistentConnection before the WebService DependencyResolver was properly set (although I am not sure why this is). The problem is solved by grabbing the ConnectionContext again for each event:

public class Notifier
{
    public static void NotifyAll(NotificationType type, object obj)
    {
        var context = GlobalHost.ConnectionManager.GetConnectionContext<EventDispatcher>();
        var output = ConstructEvent(type, obj);
        context.Connection.Broadcast(output);
    }

    protected static object ConstructEvent(NotificationType type, object obj)
    {
        var notevent = new { Event = type.ToString(), Data = obj };
        return notevent;
    }
}

Rather than:

public class Notifier
{
    static readonly IPersistentConnectionContext Context = GlobalHost.ConnectionManager.GetConnectionContext<EventDispatcher>();

    public static void NotifyAll(NotificationType type, object obj)
    {
        var output = ConstructEvent(type, obj);
        Context.Connection.Broadcast(output);
    }

    protected static object ConstructEvent(NotificationType type, object obj)
    {
        var notevent = new { Event = type.ToString(), Data = obj };
        return notevent;
    }
}

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