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asp.net-coreprovider-model

Replacement Implementation for Provider Model in ASP.NET 5

I have existing code that uses System.Configuration.Provider namespace for provider collections to plugin various implementations of interfaces, where multiple implementations exist in the collection and are selected by name according to various logic.

This namespace is not available in .net core, so I'm looking for advice on how to implement a replacement solution that will work with .net core framework.

I know that if I was just trying to plugin one implementation, I could do it by dependency injection. But I'm looking for a way to have multiple implementations available to choose based on name.

My current implementation with provider model populates the provider collection from a folder where you can drop in xml files that declare the type of the actual implementations, so new implementations of the provider can be loaded from an assembly by just adding another file to the folder. I'd like to keep the logic as similar as possible to that but I'm open to json files rather than xml.

I am thinking I could load up a collection of implementations of the interface from json files in Startup and use dependency injection to provide the collection where needed or perhaps an interface that can get the collection would be lighter weight and allow getting them when they are needed rather than at startup.

Is that the right approach? Anyone have better ideas or done something similar?

Solution

  • This is done more generically than using an abstract base class like ProviderBase in the new framework. You can register multiple of the same service with the DI framework and get them all either simply by asking for an IEnumerable<> of the type you register them as or using the GetRequiredServices<> extension method. Once you get your services, however, you'll need some other way of distinguishing them, such as a property indicating a unique name, which is the pattern the ASP.Net team has been following.

    You can see an example in the Identity framework v3 with the Token Providers.