andrew-d / urpc

Tiny RPC framework for Rust

urpc: tiny RPC framework for Rust

An RPC interface contains one or more function signatures.

urpc! {
    pub interface sort {
        fn sort(xs: Vec<u8>) -> Vec<u8> {}
    }
}

urpc! is an ordinary macro_rules! macro and will be available in Rust 1.0. It generates, among other things, a trait which you can then implement:

struct LocalSort;

impl sort::Methods for LocalSort {
    fn sort(&mut self, mut xs: Vec<u8>) -> urpc::Result<Vec<u8>> {
        xs.sort();
        Ok(xs)
    }
}

You can build an RPC server from any implementation of Methods plus any implementation of standard IO's Read + Write.

sort::serve(LocalSort, socket);

A client implements Methods by communicating with the server.

let mut client = sort::Client::new(socket);
client.sort(vec![8, 6, 7, 5, 3, 0, 9]).unwrap();

See tests/ for full examples. The protocol is simply bincode over the Read + Write stream. This library has no knowledge of sockets or networking per se (outside of the tests).

What this library does not provide: authentication, encryption, message integrity, service discovery, protocol extensibility, particularly graceful error handling, request pipelining, multiple concurrent clients, capabilities, distributed objects, etc. etc. It is perhaps a useful building block for systems providing some of the above.

My use case for this library is failure isolation for unsafe code, a context where the above features are not needed. tests/server-crash.rs shows an example of "catching" a memory corruption crash as an Err, by running the unsafe code in a child process. Combined with OS-level process sandboxing, this minimizes the security impact of vulnerable C libraries used in a Rust program, in cases where the multi-process architecture and IPC overhead are acceptable.

The library is in a very early stage and has numerous limitations, some of which are documented on the issue tracker.