Gotcha With DNX Dependency Resolution, the 'dotnet' Target Framework, and PCL

dotnet, aspnet, build, autofac comments edit

We recently released Autofac 4.0.0-beta8-157 to NuGet to coincide with the DNX beta 8 release. As part of that update, we re-added the classic PCL target .NETPortable,Version=v4.5,Profile=Profile259 (which is portable-net45+dnxcore50+win+wpa81+wp80+MonoAndroid10+Xamarin.iOS10+MonoTouch10) because older VS versions and some project types were having trouble finding a compatible version of Autofac 4.0.0 - they didn’t rectify the dotnet target framework as a match.

If you’re not up on the dotnet target framework moniker, Oren Novotny has some great articles that help a lot:

I’m now working on a beta 8 compatible version of Autofac.Configuration. For beta 7 we’d targeted dnx451, dotnet, and net45. I figured we could just update to start using Autofac 4.0.0-beta8-157, rebuild, and call it good.

Instead, I started getting a lot of build errors when targeting the dotnet framework moniker.

Building Autofac.Configuration for .NETPlatform,Version=v5.0
  Using Project dependency Autofac.Configuration 4.0.0-beta8-1
    Source: E:\dev\opensource\Autofac\Autofac.Configuration\src\Autofac.Configuration\project.json

  Using Package dependency Autofac 4.0.0-beta8-157
    Source: C:\Users\tillig\.dnx\packages\Autofac\4.0.0-beta8-157
    File: lib\dotnet\Autofac.dll

  Using Package dependency Microsoft.Framework.Configuration 1.0.0-beta8
    Source: C:\Users\tillig\.dnx\packages\Microsoft.Framework.Configuration\1.0.0-beta8
    File: lib\dotnet\Microsoft.Framework.Configuration.dll

  Using Package dependency Microsoft.Framework.Configuration.Abstractions 1.0.0-beta8
    Source: C:\Users\tillig\.dnx\packages\Microsoft.Framework.Configuration.Abstractions\1.0.0-beta8
    File: lib\dotnet\Microsoft.Framework.Configuration.Abstractions.dll

  Using Package dependency System.Collections 4.0.11-beta-23409
    Source: C:\Users\tillig\.dnx\packages\System.Collections\4.0.11-beta-23409
    File: ref\dotnet\System.Collections.dll

  (...and some more package dependencies that got resolved, then...)

  Unable to resolve dependency fx/System.Collections

  Unable to resolve dependency fx/System.ComponentModel

  Unable to resolve dependency fx/System.Core

  (...and a lot more fx/* items unresolvable.)

This was, at best, confusing. I mean, in the same target framework, I see these two things together:

  Using Package dependency System.Collections 4.0.11-beta-23409
    Source: C:\Users\tillig\.dnx\packages\System.Collections\4.0.11-beta-23409
    File: ref\dotnet\System.Collections.dll

  Unable to resolve dependency fx/System.Collections

So it found System.Collections, but it didn’t find System.Collections. Whaaaaaaa?!

After a lot of searching (with little success) I found David Fowler’s indispensible article on troubleshooting dependency issues in ASP.NET 5. This led me to the dnu list --details command, where I saw this:

[Target framework .NETPlatform,Version=v5.0 (dotnet)]

Framework references:
  fx/System.Collections  - Unresolved
    by Package: Autofac 4.0.0-beta8-157

  fx/System.ComponentModel  - Unresolved
    by Package: Autofac 4.0.0-beta8-157

  (...and a bunch more of these...)

Package references:
* Autofac 4.0.0-beta8-157
    by Project: Autofac.Configuration 4.0.0-beta8-1

* Microsoft.Framework.Configuration 1.0.0-beta8
    by Project: Autofac.Configuration 4.0.0-beta8-1

  Microsoft.Framework.Configuration.Abstractions 1.0.0-beta8
    by Package: Microsoft.Framework.Configuration 1.0.0-beta8

  System.Collections 4.0.11-beta-23409
    by Package: Autofac 4.0.0-beta8-157...
    by Project: Autofac.Configuration 4.0.0-beta8-1

  (...and so on.)

Hold up - Autofac 4.0.0-beta8-157 needs both the framework assembly and the dependency package for System.Collections?

Looking in the generated .nuspec file for the updated core Autofac, I see:

<?xml version="1.0"?>
<package xmlns="">
    <!-- ... -->
      <group targetFramework="DNX4.5.1" />
      <group targetFramework=".NETPlatform5.0">
        <dependency id="System.Collections" version="4.0.11-beta-23409" />
        <dependency id="System.Collections.Concurrent" version="4.0.11-beta-23409" />
        <!-- ... -->
      <group targetFramework=".NETFramework4.5" />
      <group targetFramework=".NETCore4.5" />
      <group targetFramework=".NETPortable4.5-Profile259" />
      <!-- ... -->
      <frameworkAssembly assemblyName="System.Collections" targetFramework=".NETPortable4.5-Profile259" />
      <frameworkAssembly assemblyName="System.ComponentModel" targetFramework=".NETPortable4.5-Profile259" />
      <frameworkAssembly assemblyName="System.Core" targetFramework=".NETPortable4.5-Profile259" />
      <frameworkAssembly assemblyName="System.Diagnostics.Contracts" targetFramework=".NETPortable4.5-Profile259" />
      <frameworkAssembly assemblyName="System.Diagnostics.Debug" targetFramework=".NETPortable4.5-Profile259" />
      <frameworkAssembly assemblyName="System.Diagnostics.Tools" targetFramework=".NETPortable4.5-Profile259" />
      <!-- ... -->

The list of failed fx/* dependencies is exactly the same as the list of frameworkAssembly references that target .NETPortable4.5-Profile259 in the .nuspec.

By removing the dotnet target framework moniker from Autofac.Configuration and compiling for specific targets, everything resolves correctly.

What I originally thought was that dotnet indicated, basically, “I support what my dependencies support,” which I took to mean, “we’ll figure out the lowest common denominator of all the dependencies and that’s the set of stuff this supports.”

What dotnet appears to actually mean is, “I support the superset of everything my dependencies support.”

The reason I take that away is that the Microsoft.Framework.Configuration 1.0.0-beta8 package targets net45, dnx451, dnxcore, and dotnet - but it doesn’t specifically support .NETPortable,Version=v4.5,Profile=Profile259. I figured Autofac.Configuration, targeting dotnet, would rectify to support the common frameworks that both core Autofac and Microsft.Framework.Configuration support… which would mean none of the <frameworkAssembly /> references targeting .NETPortable4.5-Profile259 would need to be resolved to build Autofac.Configuration.

Since they do, apparently, need to be resolved, I have to believe dotnet implies superset rather than subset.

This appears to mostly just be a gotcha if you have a dependency that targets one of the older PCL framework profiles. If everything down the stack just targets dotnet it seems to magically work.

If you’d like to try this and see it in action, check out the Autofac.Configuration repo at 14c10b5bf6 and run the build.ps1 build script.