[WIP] WASM support with grpc-web

[shravanshetty1]

@tony-iqlusion messed up the rebase

[shravanshetty1]

@tony-iqlusion Cannot remove the grpc feature since it conditionally compiles some grpc related code, which is needed for grpc_web. I think this breaks normal grpc clients and only supports grpc_web. Please review

[tony-iqlusion]

@shahankhatch looks good. want to remove [WIP]?

[shravanshetty1]

@shahankhatch looks good. want to remove [WIP]?

Unfortunately after looking more closely at the code thats being deleted. I can confidently say that this will only support grpc_web, normal grpc wont work. Will test it out when i get some time.

I am not sure whats the best solution here, we could make a seperate directoy called "cosmos-sdk-proto-wasm" or another solution could be to wait for "tonic" to enable grpc_web using some kind of feature which will be tracked in issue hyperium/tonic#645. People who want wasm grpc-web till than can use my fork.

[tony-iqlusion]

@shravanshetty1 you can conditionally gate how the tonic dependency is included depending on whether or not it's a WASM target:

https://github.com/cosmos/cosmos-rust/blob/main/cosmos-sdk-rs/Cargo.toml#L27-L28

[shravanshetty1]

@shravanshetty1 you can conditionally gate how the tonic dependency is included depending on whether or not it's a WASM target:

https://github.com/cosmos/cosmos-rust/blob/main/cosmos-sdk-rs/Cargo.toml#L27-L28

By disabling tonic, we can get wasm compatibility but we cant use grpc_web. To use grpc_web we will have to not disable tonic, but only disable the transport feature of tonic. This will make the generated code wasm compatible and allow us to use grpc_web using clients such as https://github.com/titanous/grpc-web-client.

However, since the generated code without transport feature of tonic wont allow us to use normal grpc and only force us to use grpc_web.

We could generate 2 cosmos-sdk-proto, one which is wasm+grpc_web(cosmos-sdk-proto-wasm) compatible and the other is the existing one.
We could also just wait for tonic to support grpc_web. After they support it the tonic generated code will have compilation flags which will allow us to compile for grpc_web wasm and normal based on situation.

Its your call.

[tony-iqlusion]

Aah, I guess this is where we're running into drawbacks with having pre-generated/checked-in code, in that we can't specialize things to a particular platform.

I guess for now if you have a working fork that's fine, and we should perhaps circle back on this issue after the next release (it'd be good to get one out ASAP as there's a new version of tendermint-rs)

[shravanshetty1]

For any future readers - you can find wasm+grpc_web compatible version https://github.com/shravanshetty1/cosmos-rust/tree/wasm2

[shravanshetty1]

Actually after manual testing works fine for normal grpc, not sure how