Architecture and Microsoft.AspNet.Providers

Question

I have been Googling for hours and cant find an article that is exactly related to what I need.

I have a MVC4 site with the following layers:

• Presentation layer (MVC4)
• Business Layer
• Data layer

I want to use the following provider:(installed using NuGet) Install-Package Microsoft.AspNet.Providers

My question is more of an architectural one.

In my mind, I should install this (Microsoft.AspNet.Providers) in my data layer as it is code that talks to a membership database.

All the posts I can find, however, even by Hanselman just install it in the Presentation layer / MVC4.

I am very big on separation of concerns and am using dependency injection throughout my application.

Obviously I need the config for the provider in my web.config but want all the membership code in my data layer.

Any thoughts?

thanks RuSs

PS. Would love to know the process of installing this in a data / repository layer using nuget. Slightly confused as to what DLLs Nuget is installing. If I install in my data layer, nuget doesnt update the MVC web.config.

Answer 1

The answer is quite simple actually: You should hide the providers behind an abstraction that you define in your business layer. This way you can write an adapter that implements this abstraction an wraps the provider and you can inject this adapter into your business layer using dependency injection. This way you will only have to reference the Microsoft.AspNet.Providers from your MVC4 project, and prevent any code from directly referencing the AspNet.Providers, which allows you to switch more easily later on.

Example:

// Define in business layer
public interface IAuthorizationService
{
    bool bool IsCurrentUserInRole(string role);
}

public class SomeBusinessLayerCommand
{
    private IAuthorizationService authorizer;

     public SomeBusinessLayerCommand(
         IAuthorizationService authorizer)
     {
         this.authorizer = authorizer;
     }

     public void SomeOperation()
     {
         if (this.authorizer.UserIsInRole("Admins"))
         {
             // some secret admin stuf
         }
         else
         {
             // some normal user stuf
         }
     }
}

And in your Presentation Layer you can define an adapter:

public class MembershipAdapter : IAuthorizationService
{
    public bool IsCurrentUserInRole(string role)
    {
        return Roles.IsUserInRole(role);
    }
}

And you can map IAuthorizationService to MembershipAdapter using your favorite DI container.