Protobuf-net on UWP/.NET Native and iOS

Question

I have a Xamarin.Forms App based on .NET Standard 1.4 that uses protobuf-net to store objects in the database that will be sent to a WCF service at a later time.

On Android and UWP "managed" everything works fine but - after searching through repositories, articles and blogposts that can no longer be accessed, and also after trying to get the precompilation tool to work, but failing at that - I have one simple (probably not) question: How do I get protobuf-net to work in "restricted" environments like UWP/.NET Native and iOS/Xamarin?

Answer 1

Right now I don't have a great solution for this scenario. I know some people have made it work, but I'm not expert enough in UWP / Native / iOS to give you reliable "here's the path to success" instructions.

UWP / .NET Native and iOS share (as you know) a common issue: lack of full runtime emit. I understand why this is. It is just: tricky.

Historically, protobuf-net has tried to solve this problem via a build tool that repeated the existing IL-emit usually done at runtime - as a build-time tool. This was ugly and nasty, but it worked. Kind of. To hack around some platform restrictions, protobuf-net used some of the IKVM tooling to help with this, but as the .NET framework scene has continued to expand this is basically not viable. Plus: the IKVM tool is now abandoned and won't be being maintained.

In parallel with this, there is increasing impetus to investigate some newer concepts:

• full async/await for asynchronous IO sources: note that this is extremely unfriendly to IL emit, but is almost embarrassingly easy to implement in C#
• "pipelines" / "channels" / "streams 2" - whatever it is being called this week; but: the new allocation-free IO concept that is being used in Kestrel (I helped kick this ball around a little bit when it was in the early stages, so I'm familiar with what needs doing) - note that this also ties into async/await
• and of course: how all of the above relates to pre-generation

Right now, I'm very much of the opinion that the best route forward is for the pre-gen scenario to switch to emitting C# via build-time tooling. I have repeatedly petitioned MS for improved automated C# emit based on Roslyn, but so far: no joy (vexingly: the asp.net stuff even had a fully working proof-of-concept, but it is shelved). So right now I'm thinking: we need to assume that isn't going to happen, and basically write it independently. This isn't necessarily as complex as it sounds (and: codegen of various forms is very familiar to me). The advantage of C# emit here is that I don't need to fight the intricacies of every framework - I just need to make it compile (well, and run, obviously).

So: what's holding me back? In theory: nothing. I just need to get this stuff written and deployed. In reality: life, time, etc. I am guilty of prioritising things that impact me daily, and the reality is that I'm not really a daily user of those platforms, which means I'm not feeling the pain that you're feeling. But: I hear you loud and clear, and I am trying to ramp up the v3 work that should address these points. I genuinely want to have a good story for those things - and my aim is that by moving to a C#-emit model (for pre-gen, at least): it helps me. And if it helps me I know it won't be the forgotten toy in the attic / basement that I know is there but which it is hard to find the motivation to go to the trouble of finding.