How to create application that targets both .Net 4.6.1 and Core RC2?

Assume that I’m trying to create a very simple ASP.NET Core RC2 application that takes advantage of a .Net Framework assembly, but can also run without it. The code would look something like this:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;

#if NET461
using System.DirectoryServices.AccountManagement;
#endif

namespace CoreWebApplication
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            app.Run(async context =>
            {
#if NET461
                var message = UserPrincipal.Current.ToString();
#else
                var message = "Unknown";
#endif
                await context.Response.WriteAsync(message);
            });
        }
    }
}

Here System.DirectoryServices.AccountManagement.UserPrincipal is the type from .Net Framework.

What is the right way to write project.json to make this work?

My assumption was that it would be:

"dependencies": {
  "Microsoft.NETCore.App": {
    "version": "1.0.0-rc2-3002702",
    "type": "platform"
  },
  "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final"
},

"frameworks": {
  "net461": {
    "frameworkAssemblies": {
      "System.DirectoryServices.AccountManagement": "4.0.0.0"
    }
  },
  "netcoreapp1.0": {}
},

But this fails on dotnet build with:

error NU1002: The dependency System.Runtime.Loader 4.0.0-rc2-24027 does not support framework .NETFramework,Version=v4.6.1.

What I tried next is to move the dependency on Microsoft.NETCore.App to just netcoreapp1.0:

"dependencies": {
  "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final"
},

"frameworks": {
  "net461": {
    "frameworkAssemblies": {
      "System.DirectoryServices.AccountManagement": "4.0.0.0"
    }
  },
  "netcoreapp1.0": {
    "dependencies": {
      "Microsoft.NETCore.App": {
        "version": "1.0.0-rc2-3002702",
        "type": "platform"
      }
    }
  }
},

To my surprise, this worked, both with dotnet run -f net 461 and dotnet run -f netcoreapp1.0. And now that I think about it, Microsoft.NETCore.App only being compatible with netcoreapp1.0 kind of makes sense.

My questions are:

• Is this the right way to do it?
• Is it sensible to require this kind of unobvious (at least to me), undocumented (at least I didn’t find any documentation on it) project.json manipulation for this?

(This question is to satisfy my curiousity, not any actual requirements. It was inspired by this SO question)

[dazinator]

Can someone confirm - is this the same for NETStandard.Library too? i.e does it have to go under the framework netstandard1.5 rather than in dependencies directly?

[sureshKinta]

@roshantarudkar have you solved your issue above? i am also experiencing this error and cannot find fix to it,