Previous Work

Tarpc is a previous work in this area.

You can define your service by trait and the macro tarpc::service generates all the rest of the codes.

#![allow(unused_variables)]
fn main() {
#[tarpc::service]
pub trait World {
    async fn hello(name: String) -> String;
}
}

Problems

However, I found two problems in Tarpc.

1. Tarpc isn't optimized for in-memory channel

The goal of tarpc is providing RPC through TCP channel and the direct competitor is RPC framework like Tonic or jsonrpc.

Tarpc only allows to use in-memory channel under the same abstraction so the implementation isn't optimized for in-memory channel.

2. Tarpc doesn't use Tower

Tower is a framework like Scala's Finagle which provides a abstraction called Service which is like a function from request to response and decorator stacks to add more functionality on top of the abstraction.

If we design a RPC framework from scratch with the current Rust ecosystem, we will 100% choose to depend on Tower to implement functionalities like rate-limiting or timeout which is essential in doing RPC. In fact, Tonic does so.

However, Tarpc's started a long ago before the current Rust ecosystem is established and it doesn't use Tower but implements those functionalities by itself.