JSON-RPC 2.0 over stdio

[ctaggart]

The extensions communicate over stdio, using JSON-RPC 2.0. This is how to do that using Rust. cargo build --target=wasm32-wasi works as well.

To test, run cargo run or cargo wasi run and

Entering this request line:

{"jsonrpc": "2.0", "method": "say_hello", "id": 1}

Will respond with this line:

{"jsonrpc":"2.0","result":"Hello World!","id":1}

links
paritytech/jsonrpsee#122
Azure/autorest#3502 (comment)