Rx.NET 3.0 with Xamarin.Android

[jmezach]

I'm trying to use the new Rx.NET 3.0 version with Xamarin.Android but I'm getting a compile error after installing the packages. The error message is:

Error   CS1703  Multiple assemblies with equivalent identity have been imported: 'C:\Projects\NS\Kanzi.Mobile\packages\System.Runtime.InteropServices.WindowsRuntime.4.0.1\lib\netstandard1.3\System.Runtime.InteropServices.WindowsRuntime.dll' and 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\MonoAndroid\v1.0\Facades\System.Runtime.InteropServices.WindowsRuntime.dll'. Remove one of the duplicate references.  Mobile.Core.Android C:\Projects\NS\Kanzi.Mobile\Mobile.Core.Android\CSC 1   Active

I can see the reference to the System.Runtime.InteropServices.WindowsRuntime assembly from the associated package in my projects reference. Not sure where the other assembly comes from, but I'm assuming this is included automagically by the build system.

Is this supposed to work at all? I'm using the latest stable Xamarin version (4.1.2.18) and Xamarin.Android version (6.1.2.21) with Visual Studio 2015 Update 3.

[shiftkey]

I'm really not sure what's happening here, both of these packages seem to be external to System.Reactive:

• 'C:\Projects\NS\Kanzi.Mobile\packages\System.Runtime.InteropServices.WindowsRuntime.4.0.1\lib\netstandard1.3\System.Runtime.InteropServices.WindowsRuntime.dll'
• 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\MonoAndroid\v1.0\Facades\System.Runtime.InteropServices.WindowsRuntime.dll'

Can you tell me:

• what package you were installing before this error occurred?
• what version of NuGet Package Manager you have installed in VS2015?
• if you have a project.lock.json file in the project folder, please attach the contents so we can see what might be responsible for this System.Runtime.InteropServices.WindowsRuntime dependency

[jmezach]

I was installing System.Reactive 3.0.0. When I install that package I get the following dependencies for free:

System.Collections.4.0.11
System.Collections.Concurrent.4.0.12
System.ComponentModel.4.0.1
System.Diagnostics.Debug.40.11
System.Diagnostics.Tools.4.0.1
System.Globalization.4.0.11
System.Linq.4.1.0
System.Reactive.Interfaces.3.0.0
System.Reflection.4.1.0
System.Resources.ResourceManager.4.0.1
System.Runtime.4.1.0
System.Runtime.Extensions.4.1.0
System.Runtime.InteropServices.WindowsRuntime.4.0.1
System.Threading.4.0.11
System.Threading.Tasks.4.0.11
System.Reactive.Core.3.0.0
System.Reactive.Linq.3.0.0
System.Reactive.PlatformServices.3.0.0
System.Reactive.3.0.0

As you can see that list includes the System.Runtime.InteropServices.WindowsRuntime package which is where things start to fail.

I'm using version 3.5.0.1484 of the NuGet package explorer. Unfortunately I do not have a project.lock.json file since I'm not using the project.json/xproj project system but using regular csproj's.

[shiftkey]

Here's your problem dependency - hiding inside System.Reactive.Linq.

Unfortunately I'm really rusty on the Xamarin side of things and whether the facade is still correct to be using here. Hopefully someone else has some ideas here.

[jmezach]

Well, I tried removing the reference to the assembly from the package, but then a release build fails with a linker error, probably because something in System.Reactive depends on a type that is defined in that assembly which does not exist in the facade assembly. Not sure if I can try it the other way around (removing the Facade assembly from the mix) and see if that works.

[clairernovotny]

That System.Runtime.InteropServices.WindowsRuntime assembly is part of the PCL 259 façade/surface area and Xamarin does support it (there's no real implementation there, it's just a few types).

Do you have a repro project as it should work? I would recommend using project.json for all project types, including Xamarin, as it works better and may solve your issue. My blog shows how: https://oren.codes/2016/02/08/project-json-all-the-things/

[jmezach]

I just created a brand new Android Class Library project and installed the System.Reactive 3.0.0 package into it and I get the compile error. You can find the sources here.

We've downgraded to the Rx-Main 2.2.5 package for now. I'll need to have a look at converting this to project.json since I had some issues with that in the past, especially with creating a NuGet package from a project that has project.json.

[RolandPheasant]

@jmezach I am ignorant about xamarin. However I have just updated DynamicData (which is portable and depends on rx) to NetStandard and was looking for a quick way to test it with xamarin.

In short I had the same problem until I downloaded and tested it using SampleXamFormsWithNetStandard. The correct way to use xamarin with NetStandard is explained here. However moving to NetStandard may not be what you want right now.

@onovotny FYI I had the following build error: The "CreateAdditionalLibraryResourceCache" task failed unexpectedly. It turns out this is caused by a long file path which I had to shorten. I mention this in case anyone else gets the same problem

[Odonno]

Same problem as you have. Xamarin.iOS, .NET and UWP library projects has no problem but the Xamarin.Android give me the same error when I compile...

[frankbuckley]

We were hoping that previous NuGet problems were solved with latest Xamarin bits and we could move to 3.0.0 - but, no, we are seeing this error in Xamarin Android projects. Not sure who needs to fix what, but have logged report with Xamarin:

https://bugzilla.xamarin.com/show_bug.cgi?id=44165

[jahmai-ca]

I believe the problem lies with the System.Runtime.InteropServices.WindowsRuntime nuget package, it doesn't contain an empty definition for Xamarin.Android, but does for Xamarin.iOS.

[shiftkey]

This line seems interesting but I'm unclear on how the packaging of the corefx bits works to confirm this is where we need to address it 😕

[clairernovotny]

I just bugged it here: https://github.com/dotnet/corefx/issues/12070. Not sure what the right answer is gien that Xamarin does support .NET Standard 1.6 and is thus pulling in the netstandard1.3 package.