Note this integration is no longer distributed with the core download and needs to be built from source. It may be moved to Contrib in V2.

Introduction

The MEF integration allows you to expose extensibility points in your Autofac applications using the Managed Extensibility Framework.

Referenced Assemblies

To use MEF in an Autofac application, you must reference both System.ComponentModel.Composition.dll and Autofac.Integration.Mef.dll.

Consuming MEF Extensions in Autofac

The Autofac/MEF integration allows MEF catalogs to be registered with the ContainerBuilder.

First, the Autofac.Integration.Mef namespace must be included:

using Autofac.Integration.Mef;

Catalogs containing extensions are registered with the RegisterCatalog() method:

var builder = new ContainerBuilder();
var catalog = new DirectoryCatalog("C\MyExtensions");
builder.RegisterCatalog(catalog);

All MEF catalog types are supported:

• TypeCatalog
• AssemblyCatalog
• DirectoryCatalog

Once MEF catalogs are registered, exports within them can be resolved through the Autofac container or by injection into other components:

[Export(typeof(IFoo))]
public class Foo : IFoo { }

// ...

var fooCatalog = new TypeCatalog(typeof(Foo));
builder.RegisterCatalog(fooCatalog);
var container = builder.Build();
var foo = container.Resolve<IFoo>();

Providing Autofac Components to MEF Extensions

Autofac components aren't automatically available for MEF extensions to import.

To provide an Autofac component to MEF, the ExportedAs() method must be used:

builder.Register<Foo>().ExportedAs<IFoo>();

Implicit Collection Support

If multiple MEF extensions will support the same extension point, the ImplicitCollectionSupport module will make it easier to consume them.