Generating RPC Types From Metadata (Once Reflected) about capi

[niklasad1]

we already got an issue for that paritytech/jsonrpsee#737 but just a matter to get someone working on it :)

[niklasad1]

It's really tricky because these rpc's can be defined in so many places in substrate, frame, runtime APIs, RPC extensions and similar.

Ideally, I would want to have a method e.g. "rpc_methods/rpc.discover" to have all information from a node which RPC methods it exposes to generate the RPC API with parameters and return types.

There is this https://spec.open-rpc.org/#openrpc-document which is a standard how to this in JSON-RPC v2 which looks cool
but we haven't looked into it and how well it works with all the generics stuff in substrate.

[harrysolovay]

There is this https://spec.open-rpc.org/#openrpc-document which is a standard how to this in JSON-RPC v2 which looks cool

This spec looks fantastic; in fact, it seems trpc––a popular TS dev tool––complies with the OpenRPC specification. Very promising.

As we build out more libraries, utilizing a single source of truth for RPC types (and devising an approach to handle variation across chains) will become a necessity. The rpc.discover method would address this need quite well; it would even enable the generation of narrow typings for errors of each method.

I can imagine that this would entail a non-trivial amount of work. Perhaps a first pass could omit the method result content descriptors / reference objects. Meanwhile, params are usually just numbers / hex-encoded strings; these would be simpler to represent than the complex generic types of Substrate.

^ might not be helpful, just hoping to get the ball rolling. Let me know if I should transfer this issue to one of your repos. Might make for a good backlog item.

[tjjfvi]

We'll be using state_call, so we won't need these types.