Async Rust JSONRPC framework

The implementation is modeled on tower::Service, but does not use it directly. The reason is that tower::Service is not async and hence is less ergonomic than it could be otherwise.

NOTE: There is tower-async, but it requires nightly compiler.

(VHLD) Very High Level Description

pub trait JsonRpc2 {
    const METHOD: &'static str;
    type Request: fmt::Debug + Serialize + de::DeserializeOwned;
    type Response: fmt::Debug + Serialize + de::DeserializeOwned;
    type Error: fmt::Debug + Serialize + de::DeserializeOwned;
}

pub trait JsonRpc2Service<Request> {
    type Response;
    type Error;
    async fn call(&self, request: Request) -> Result<Self::Response, Self::Error>;
}

These two traits are what it takes for a consumer to implement the RPC server and client.

See pingpong crate for an example of implementing it.

Derive JsonRpc2

#[derive(Debug, JsonRpc2)]
#[jsonrpc(
    method = "frob",
    request = "FrobRequest",
    response = "FrobResponse",
    error = "FrobError",
    crates(jsonrpc = "my_jsonrpc", serde_json = "json"),
    client = "FrobClient",
)]
struct Frob;

Attributes

method - String, Required. JSONRPC method name.

request - Struct name, Optional. The name of the request object struct. Defaults to XxxRequest, where Xxx is derive target.

response - Struct name, Optional. The name of the response object struct. Defaults to XxxResponse, where Xxx is derive target.

error - Struct name, Optional.The name os the error object struct. Defaults to XxxError, where Xxx is derive target.

crates - Attribute list, Optional. When jsonrpc and/or serde_json crates are renamed, specifies their new names.

client - Client extension trait generation attribute. Optional. If not present, client extension trait is not generated. If present without value - client extension trait is generated for jsonrpc::AsyncClient<T> If present with value then client extension trait is generated for the given type which should be AsRef<jsonrpc::AsyncClient<T>>

pub struct FrobClient(jsonrpc::AsyncClient<T>);

impl<T> AsRef<jsonrpc::AsyncClient<T>> for FrobClient<T> {
    fn as_ref(&self) -> &jsonrpc::AsyncClient<T> {
        &self.0
    }
}