SignalR + Dependency Injection Questions

Question

I am using SignalR in my MVC3 application, and since I have implemented StructureMap Dependency Injection on my controllers I would like to do the same in my hub, but I can't seem to get it working.

Please tell me what's wrong with my codes below:

SignalRSmDependencyResolver.cs

public class SignalRSmDependencyResolver : DefaultDependencyResolver
{
    private IContainer _container;

    public SignalRSmDependencyResolver(IContainer container)
    {
        _container = container;
    }

    public override object GetService(Type serviceType)
    {
        object service = null;
        if (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
        {
            // Concrete type resolution
            service = _container.GetInstance(serviceType);
        }
        else
        {
            // Other type resolution with base fallback
            service = _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
        }
        return service;
    }

    public override IEnumerable<object> GetServices(Type serviceType)
    {
        var objects = _container.GetAllInstances(serviceType).Cast<object>();
        objects.Concat(base.GetServices(serviceType));
        return objects;
    }
}

SignalRExtensionsRegistry.cs

public class SignalRExtensionsRegistry : Registry
{
    public SignalRExtensionsRegistry()
    {
        For<IDependencyResolver>().Add<SignalRSmDependencyResolver>();
    }
}

IoC.cs

public static class IoC {
    public static IContainer Initialize() {

        var container = BootStrapper.Initialize();

        container.Configure(x =>
        {
            x.For<IControllerActivator>().Singleton().Use<StructureMapControllerActivator>();
        });

        return container;
    }
}

public class StructureMapControllerActivator : IControllerActivator {
    public StructureMapControllerActivator(IContainer container) {
        _container = container;
    }

    private IContainer _container;

    public IController Create(RequestContext requestContext, Type controllerType) {
        IController controller = DependencyResolver.Current.GetService(controllerType) as IController;
        return controller;
    }
}

AppStart_Structuremap.cs

[assembly: WebActivator.PreApplicationStartMethod(typeof(StoreUI.AppStart_Structuremap), "Start")]

namespace MyNameSpace {
public static class AppStart_Structuremap {
    public static void Start() {
        var container = (IContainer) IoC.Initialize();
        DependencyResolver.SetResolver(new StructureMapDependenceyResolver(container));
        AspNetHost.SetResolver(new StructureMapDependencyResolver(container));            
    }
}
}

NotificationsHub.cs

[HubName("notificationsHub")]
public class NotificationsHub : Hub
{    
    #region Declarations
    private readonly IUserService userService;
    #endregion

    #region Constructor

    public NotificationsHub(IUserService userService)
    {
        this.userService = userService;
    }

    #endregion

    public void updateServer(string message)
    {
        Clients.updateClient(message);
    }
}

Thanks

Answer 1

Getting Structuremap into SignalR is actually pretty easy. First you want to create your own resolver:

StructureMap Resolver

Usings:

using SignalR.Infrastructure;
using StructureMap;

Class:

public class StructureMapResolver : DefaultDependencyResolver
{
    private IContainer _container;

    public StructureMapResolver(IContainer container)
    {
        _container = container;
    }

    public override object GetService(Type serviceType)
    {
        object service = null;
        if (!serviceType.IsAbstract && !serviceType.IsInterface && serviceType.IsClass)
        {
            // Concrete type resolution
            service = _container.GetInstance(serviceType);
        }
        else
        {
            // Other type resolution with base fallback
            service = _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
        }
        return service;
    }

    public override IEnumerable<object> GetServices(Type serviceType)
    {
        var objects = _container.GetAllInstances(serviceType).Cast<object>();
        return objects.Concat(base.GetServices(serviceType));
    }
}

The idea here is to try and use your container to resolve the dependencies, if you do not have the dependency wired up, pass it through to the default resolver. This way you don't have to worry about all of the other dependencies in SignalR and can focus only on the stuff you want to inject into (Hubs, ConnectionIdFactory, MessageBus, etc.).

Bindings for Resolver and Hub

Next you will want to register this in your container (i like using registries):

Usings:

using SignalR.Infrastructure;
using StructureMap.Configuration.DSL;

Class:

public class ExtensionsRegistry : Registry
{
    public ExtensionsRegistry()
    {
        For<IDependencyResolver>().Add<StructureMapResolver>();
    }
}

Resolver Replacement

Finally you will want to tell SignalR to use your resolver instead of the default:

Global::Application_Start or WebActivator::Pre_Start

Usings:

using SignalR.Hosting.AspNet;
using SignalR.Infrastructure;

Application_Start:

// Make sure you build up the container first
AspNetHost.SetResolver(StructureMap.ObjectFactory.GetInstance<IDependencyResolver>());

Silly Hub with injected dependencies

Now you can just inject any dependencies your container knows about into the hubs themselves:

[HubName("defaultHub")]
public class DefaultHub : Hub, IDisconnect
{
    private readonly IRepository _repo;
    public DefaultHub(IRepository repo)
    {
        _repo = repo;
    }

    public void Connect()
    {
        Caller.setUser(Context.ConnectionId);
        Clients.addMessage(string.Format("{0} has connected", Context.ConnectionId));
    }

    public void MessageSender(string message)
    {
        Caller.addMessage(_repo.RepositoryMessage());
        Clients.addMessage(message);
    }

    public Task Disconnect()
    {
        var clientId = this.Context.ConnectionId;
        return Task.Factory.StartNew(() => { Clients.addMessage(string.Format("{0} has disconnected", clientId)); });
    }
}

Answer 2

Have you followed the instructions here:- https://github.com/SignalR/SignalR/wiki/Extensibility ?

You'll need to use AspNetHost.SetResolver.

Answer 3

I know this is an old thread, but for those who are wondering where is the AspNetHost.SetResolver in the newer version of signalR, you can use this in the App_Start StructuremapMvc.cs:

    public static void Start() {
        IContainer container = IoC.Initialize();
        GlobalHost.DependencyResolver = new SignalRSmDependencyResolver(container); // for signalR

        DependencyResolver.SetResolver(new StructureMapDependencyResolver(container));
        GlobalConfiguration.Configuration.DependencyResolver = new StructureMapDependencyResolver(container);
    }

Answer 4

Add something like this to a file in your App_Start folder. This code snippet is for Ninject, so just replace AspNetHost.SetResolver()

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using Ninject;
using SignalR.Hosting.AspNet;
using SignalR.Infrastructure;
using SignalR.Ninject;
using Web.Models;

[assembly: WebActivator.PreApplicationStartMethod(typeof(Web.App_Start.NinjectSignalR), "Start")]

namespace Web.App_Start
{
    public static class NinjectSignalR
    {
        public static void Start()
        {
            IKernel kernel = CreateKernel();
            // switch this line to the structuremap resolver
            AspNetHost.SetResolver(new NinjectDependencyResolver(kernel));
        }

        private static IKernel CreateKernel()
        {
            var kernel = new StandardKernel();
            RegisterServices(kernel);
            return kernel;
        }

        private static void RegisterServices(IKernel kernel)
        {
            // add your services here
            //kernel.Bind<IRepository>().To<Repository>();
        }
    }
}