feat: add retroactive support for core API to 0.45.x

[aaronc]

Description

This demonstrates how 0.45.x (or really any older SDK version) could be adapted to support modules written with the core API. This can allow us to write new modules which don't depend on any mainline SDK release (just core) but can be used with any SDK version.

The core API is currently incomplete and doesn't have support for things like registering services, begin/end blockers, events, etc. Those things should also be pretty straightforward to add and hopefully this proof of concept shows how this can work for multi-SDK version compatibility of standalone modules.

There are two parts to this adaptor:

• core_module.go has a function UseCoreAPIModule to wrap a core API module as one that v0.45.x understands as an AppModule
• core_serices.go which allows implementing the services core API modules will consume without depending directly on sdk.Context.

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[tac0turtle]

@aaronc does someone need to take over this?

[aaronc]

@aaronc does someone need to take over this?

That would be ideal

[alexanderbez]

Can you describe what else needs to be done?

[aaronc]

Can you describe what else needs to be done?

Testing it with mock modules

[facundomedica]

I'm picking this one up 👍

[facundomedica]

@aaronc this is pretty much done, but it lacks the EndBlock and BeginBlock methods. Is that something we should backport too right?

[aaronc]

Yes for sure

[alexanderbez]

Is there a plan to complete the backporting for the full core API service? I.e. begin blockers. Also, is there an example of how a module would use this adapter? e.g. x/bank

[aaronc]

Is there a plan to complete the backporting for the full core API service? I.e. begin blockers. Also, is there an example of how a module would use this adapter? e.g. x/bank

Yes, although maybe things like event listeners and inter-module client don't get backported. We'd want to use a module that only uses core API as an example. Maybe x/circuit will?

[tac0turtle]

lets add a changelog entry.

[aaronc]

We should make it clear in documentation somehow that there will be limits on how much of core API can retroactively be supported. ADR 033 and event listeners obviously no. Also, if we do things with Msg's to remove the bech32 sdk.AccAddress dependency and support protoreflect, there will need to be other backports to 0.45 to support that... or it will just be an unsupported part of core API.

[tac0turtle]

We should make it clear in documentation somehow that there will be limits on how much of core API can retroactively be supported. ADR 033 and event listeners obviously no. Also, if we do things with Msg's to remove the bech32 sdk.AccAddress dependency and support protoreflect, there will need to be other backports to 0.45 to support that... or it will just be an unsupported part of core API.

I think it will be unsupported. There isn't a large need to backport these items, but it's useful. Once we have better docs and people know what's possible then if we get requests to backport them we can evaluate on a per case basis