Runtime IDs

The Microsoft.NETCore.Platforms transport package contains the portable and non-portable runtime identifier graph files for redistribution in the dotnet/sdk repository.

What is a RID?

A RID is an opaque string that identifies a platform. RIDs have relationships to other RIDs by "importing" the other RID. In that way a RID is a directed graph of compatible RIDs.

How does NuGet use RIDs?

When NuGet is deciding which assets to use from a package and which packages to include NuGet will consider a RID if the project.json lists a RID in its runtimes section.

• NuGet chooses the best RID-specific asset, where best is determined by a breadth first traversal of the RID graph. Breadth ordering is document order.
• NuGet considers RID-specific assets for two asset types: lib and native.
• NuGet never considers RID-specific assets for compile.

Best RID

Consider the partial RID-graph:

        "any": {},

        "win": {
            "#import": [ "any" ]
        },
        "win-x86": {
            "#import": [ "win" ]
        },
        "win-x64": {
            "#import": [ "win" ]
        },
        "win7": {
            "#import": [ "win" ]
        },
        "win7-x86": {
            "#import": [ "win7", "win-x86" ]
        },
        "win7-x64": {
            "#import": [ "win7", "win-x64" ]
        }

This can be visualized as a directed graph, as follows:

    win7-x64    win7-x86
       |   \   /    |
       |   win7     |
       |     |      |
    win-x64  |  win-x86
          \  |  /
            win
             |
            any

As such, best RID, when evaluating for win7-x64 would be:win7-x64, win7, win-x64, win, any Similarly, when evaluating for win-x64: win-x64, win, any Note that win7 comes before win-x64 due to the import for win7 appearing before the import for win-x64 in document order.

RID-qualified assets are preferred

NuGet will always prefer a RID-qualified asset over a RID-less asset. For example if a package contains

lib/netcoreapp1.0/foo.dll
runtimes/win/lib/netcoreapp1.0/foo.dll

When resolving for netstandard1.0/win7-x64 NuGet will choose runtimes/win/lib/netcoreapp1.0/foo.dll.

Additionally, NuGet will always prefer a RID-qualified asset over a RID-less asset, even if the framework is less specific for the RID-qualified asset.

lib/netstandard1.5/foo.dll
runtimes/win/lib/netstandard1.0/foo.dll

When resolving for netstandard1.5/win7-x64 NuGet will choose runtimes/win/lib/netstandard1.0/foo.dll over lib/netstandard1.5/foo.dll even though netstandard1.5 is more specific than netstandard1.0.

RID-qualified assets are never used for compile

NuGet will select different compile-assets than runtime-assets. The compile assets can never be RID-qualified. Consider the package:

lib/netstandard1.5/foo.dll
runtimes/win/lib/netstandard1.0/foo.dll

When resolving for netstandard1.5/win7-x64 will select lib/netstandard1.5/foo.dll for the compile asset and runtimes/win/lib/netstandard1.0/foo.dll for the runtime asset.

Adding new RIDs

The RID graphs should be only updated with new base OSes, architectures, or C standard libraries. The RID graphs shouldn't be updated with new OS flavor- and version-specific RIDs anymore. Build from source automatically adds the non-portable distro RID encoded via the OutputRID property into the RID graph which allows build tools to target that RID.