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At the risk of stepping into holy war territory, What are the strengths and weaknesses of these popular DI/IoC frameworks, and could one easily be considered the best? ..:

  • Ninject
  • Unity
  • Castle.Windsor
  • Autofac
  • StructureMap

Are there any other DI/IoC Frameworks for C# that I haven't listed here?

In context of my use case, I'm building a client WPF app, and a WCF/SQL services infrastructure, ease of use (especially in terms of clear and concise syntax), consistent documentation, good community support and performance are all important factors in my choice.


The resources and duplicate questions cited appear to be out of date, can someone with knowledge of all these frameworks come forward and provide some real insight?

I realise that most opinion on this subject is likely to be biased, but I am hoping that someone has taken the time to study all these frameworks and have at least a generally objective comparison.

I am quite willing to make my own investigations if this hasn't been done before, but I assumed this was something at least a few people had done already.

Second Update:

If you do have experience with more than one DI/IoC container, please rank and summarise the pros and cons of those, thank you. This isn't an exercise in discovering all the obscure little containers that people have made, I'm looking for comparisons between the popular (and active) frameworks.

Best Answer:

Disclaimer: As of early 2015, there is a great comparison of IoC Container features from Jimmy Bogard, here is a summary:

Compared Containers:

  • Autofac
  • Ninject
  • Simple Injector
  • StructureMap
  • Unity
  • Windsor

The scenario is this: I have an interface, IMediator, in which I can send a single request/response or a notification to multiple recipients:

public interface IMediator 
    TResponse Send<TResponse>(IRequest<TResponse> request);
    Task<TResponse> SendAsync<TResponse>(IAsyncRequest<TResponse> request);
    void Publish<TNotification>(TNotification notification)
        where TNotification : INotification;
    Task PublishAsync<TNotification>(TNotification notification)
        where TNotification : IAsyncNotification; 

I then created a base set of requests/responses/notifications:

public class Ping : IRequest<Pong>
    public string Message { get; set; }
public class Pong
    public string Message { get; set; }
public class PingAsync : IAsyncRequest<Pong>
    public string Message { get; set; }
public class Pinged : INotification { }
public class PingedAsync : IAsyncNotification { }

I was interested in looking at a few things with regards to container support for generics:

  • Setup for open generics (registering IRequestHandler<,> easily)
  • Setup for multiple registrations of open generics (two or more INotificationHandlers)

Setup for generic variance (registering handlers for base INotification/creating request pipelines) My handlers are pretty straightforward, they just output to console:

public class PingHandler : IRequestHandler<Ping, Pong> { /* Impl */ }
public class PingAsyncHandler : IAsyncRequestHandler<PingAsync, Pong> { /* Impl */ }
public class PingedHandler : INotificationHandler<Pinged> { /* Impl */ }
public class PingedAlsoHandler : INotificationHandler<Pinged> { /* Impl */ }
public class GenericHandler : INotificationHandler<INotification> { /* Impl */ }
public class PingedAsyncHandler : IAsyncNotificationHandler<PingedAsync> { /* Impl */ }
public class PingedAlsoAsyncHandler : IAsyncNotificationHandler<PingedAsync> { /* Impl */ }


var builder = new ContainerBuilder();
builder.RegisterSource(new ContravariantRegistrationSource());
builder.RegisterAssemblyTypes(typeof (IMediator).Assembly).AsImplementedInterfaces();
builder.RegisterAssemblyTypes(typeof (Ping).Assembly).AsImplementedInterfaces();
  • Open generics: yes, implicitly
  • Multiple open generics: yes, implicitly
  • Generic contravariance: yes, explicitly


var kernel = new StandardKernel();
kernel.Components.Add<IBindingResolver, ContravariantBindingResolver>();
kernel.Bind(scan => scan.FromAssemblyContaining<IMediator>()
kernel.Bind(scan => scan.FromAssemblyContaining<Ping>()
  • Open generics: yes, implicitly
  • Multiple open generics: yes, implicitly
  • Generic contravariance: yes, with user-built extensions

Simple Injector

var container = new Container();
var assemblies = GetAssemblies().ToArray();
container.Register<IMediator, Mediator>();
container.Register(typeof(IRequestHandler<,>), assemblies);
container.Register(typeof(IAsyncRequestHandler<,>), assemblies);
container.RegisterCollection(typeof(INotificationHandler<>), assemblies);
container.RegisterCollection(typeof(IAsyncNotificationHandler<>), assemblies);
  • Open generics: yes, explicitly
  • Multiple open generics: yes, explicitly
  • Generic contravariance: yes, implicitly (with update 3.0)


var container = new Container(cfg =>
    cfg.Scan(scanner =>
  • Open generics: yes, explicitly
  • Multiple open generics: yes, explicitly
  • Generic contravariance: yes, implicitly


/* later down */
static bool IsNotificationHandler(Type type)
    return type.GetInterfaces().Any(x => x.IsGenericType && (x.GetGenericTypeDefinition() == typeof(INotificationHandler<>) || x.GetGenericTypeDefinition() == typeof(IAsyncNotificationHandler<>)));
static LifetimeManager GetLifetimeManager(Type type)
    return IsNotificationHandler(type) ? new ContainerControlledLifetimeManager() : null;
static string GetName(Type type)
    return IsNotificationHandler(type) ? string.Format("HandlerFor" + type.Name) : string.Empty;
  • Open generics: yes, implicitly
  • Multiple open generics: yes, with user-built extension
  • Generic contravariance: derp


var container = new WindsorContainer();
container.Kernel.AddHandlersFilter(new ContravariantFilter());
  • Open generics: yes, implicitly
  • Multiple open generics: yes, implicitly
  • Generic contravariance: yes, with user-built extension

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