expose jsonrpc-core client

[seunlanlege]

We depend on the jsonrpc-core client so we can make typed rpc requests

eg: https://github.com/ComposableFi/hyperspace/blob/311bc18ac6d4b24ed4586ba98552e9e145b0b068/parachain/src/provider.rs#L335-L342

[niklasad1]

There is already an Deref impl for the rpc client, why can't you use that?

[seunlanlege]

There is already an Deref impl for the rpc client, why can't you use that?

yes but this derefs to your custom trait, not jsonrpsee::ClientT. Exposing that trait doesn't even make it usable, i still have to do this ridiculously unsafe cast to use it:

https://github.com/ComposableFi/centauri/blob/903aa7ccefe218e8bcbd4e1dd1a7ec8081f864f0/algorithms/grandpa/prover/src/lib.rs#L119-L122

[jsdw]

How about instead of this, the existing Deref impl is modified to return &Arc<dyn RpcClientT> rather than &dyn rpcClientT as it does at the mo? the Arc will Deref anyway so it shouldn't alter anything, and it'll give you access to the arc as well so that you can clone it or whatever.

You'd still ened to cast from the Arc<dyn RpcClientT> to the jsonrpsee client though; the RPC client in subxt is generic and doesn't have to be jsonrpsee at all (in fact, given the current interface we do reserve the right to change that and invalidate said casting without a major version bump).

[jsdw]

Another, safer, approach for you may just be to clone and keep hold of a copy of the original jsonrpsee Client itself rather than having to cast a dyn RpcClientT? This means constructing it explicitly and then passing it to the OnlineClient::from_rpc_client method (as well as cloning it to keep separately), but if you want access to the same client subxt is using, that is probably the safest option and avoids any casting (which may break in the future) or whatever.

I don't mind exposing the Arc<dyn RpcClientT> but I don't think it's the best way to go.

[seunlanlege]

Another, safer, approach for you may just be to clone and keep hold of a copy of the original jsonrpsee Client itself rather than having to cast a dyn RpcClientT? This means constructing it explicitly and then passing it to the OnlineClient::from_rpc_client method (as well as cloning it to keep separately), but if you want access to the same client subxt is using, that is probably the safest option and avoids any casting (which may break in the future) or whatever

I've modified the PR with this approach

[niklasad1]

LGTM, just to run cargo fmt to make the CI happy.

[jsdw]

LGTM once fmt is ran and we've fixed our tests; thanks!

[seunlanlege]

LGTM, just to run cargo fmt to make the CI happy.

Done 🙏🏿