.NET Web Abstractions

IApplication.cs

// Func<IRequest, IResponse>
public interface IApplication {
    IAsyncResult BeginInvoke(IRequest request, AsyncCallback callback, object state);
    IResponse EndInvoke(IAsyncResult result);
}

IRequest.cs

public interface IRequest {
    string Method {get;}
    string Uri {get;}
    IDictionary<string, IEnumerable<string>> Headers {get;}
    // Set custom, app-specific settings here.
    IDictionary<string, object> Items {get;}
    // Assume the request input is a System.IO.Stream.
    IAsyncResult BeginReadInput(byte[] buffer, int offset, int count, AsyncCallback callback, object state);
    int EndReadInput(IAsyncResult result);
}

IResponse.cs

public interface IResponse {
    string Status {get;} // "200 OK"
    IDictionary<string, IEnumerable<string>> Headers {get;}
    //IEnumerable Body {get;}
    IEnumerable GetBody();
}

Should Header values be a simple IEnumerable instead of IEnumerable<string>?

@serialseb brought up a great question: Is IMiddleware necessary? Not sure given the interfaces above. How would you chain apps together?