# Factory-based middleware activation with a third-party container in ASP.NET Core
By [Luke Latham](https://github.com/guardrex)
This article demonstrates how to use [IMiddlewareFactory](/dotnet/api/microsoft.aspnetcore.http.imiddlewarefactory) and [IMiddleware](/dotnet/api/microsoft.aspnetcore.http.imiddleware) as an extensibility point for [middleware](xref:fundamentals/middleware/index) activation with a third-party container. For introductory information on `IMiddlewareFactory` and `IMiddleware`, see the [Factory-based middleware activation](xref:fundamentals/middleware/extensibility) topic.
[View or download sample code](https://github.com/aspnet/Docs/tree/master/aspnetcore/fundamentals/middleware/extensibility-third-party-container/sample) ([how to download](xref:tutorials/index#how-to-download-a-sample))
The sample app demonstrates middleware activation by an `IMiddlewareFactory` implementation, `SimpleInjectorMiddlewareFactory`. The sample uses the [Simple Injector](https://github.com/simpleinjector/SimpleInjector) dependency injection (DI) container.
The sample's middleware implementation records the value provided by a query string parameter (`key`). The middleware uses an injected database context (a scoped service) to record the query string value in an in-memory database.
> The sample app uses [Simple Injector](https://github.com/simpleinjector/SimpleInjector) purely for demonstration purposes. Use of Simple Injector isn't an endorsement. Middleware activation approaches described in the Simple Injector documentation and GitHub issues are recommended by the maintainers of Simple Injector. For more information, see the [Simple Injector documentation](https://simpleinjector.readthedocs.io/en/latest/index.html) and [Simple Injector GitHub repository](https://github.com/simpleinjector/SimpleInjector).
[IMiddlewareFactory](/dotnet/api/microsoft.aspnetcore.http.imiddlewarefactory) provides methods to create middleware.
In the sample app, a middleware factory is implemented to create an `SimpleInjectorActivatedMiddleware` instance. The middleware factory uses the Simple Injector container to resolve the middleware:
