Electron's Super Simple RPC (ESSRPC) is a lightweight RPC library which aims to enable RPC calls as transparently as possible through calls to ordinary trait methods.

The magic is performed by the essrpc attribute macro which may be applied to any trait whose functions each meet the following conditions:

• Returns a Result whose error type implements From<RPCError>.
• Uses only parameter and returns types which implement Serialize
• Is not unsafe

The essrpc macro generates for a trait an RPC client and a server. For a trait named Foo, the macro will generate FooRPCClient which implements both RPCClient and Foo as well as FooRPCServer which implements RPCServer.

Examples

A trait can apply the essrpc attribute like this.

#[essrpc]
pub trait Foo {
fn bar(&self, a: String, b: i32) -> Result<String, SomeError>;
}

For example purposes, assume we're using a unix socket to communicate between a parent and child process. Anything else implementing Read+Write would work just as well.

# use std::os::unix::net::UnixStream;
let (s1, s2) = UnixStream::pair().unwrap();

We can spin up a server like this

let mut s = FooRPCServer::new(FooImpl::new(), BincodeTransport::new(s2));
s.serve()

Then, if we have some type FooImpl which implements Foo, we can do RPC like this.

let client = FooRPCClient::new(BincodeTransport::new(s1));
match client.bar("the answer".to_string(), 42) {
Ok(result) => assert_eq!("the answer is 42", result),
Err(e) => panic!("error: {:?}", e)
}

Asynchronous Clients

By default, the #[essrpc] attribute generates a synchronous client. Asynchronous clients can be generated via #[essrpc(async)], or #[essrpc(sync, async)] if both synchronous and asynchronous clients are needed. For asynchronous, the macro generates a new trait, suffixed with Async for which every method returns a boxed Future instead of a Result, with the same success and error types, and a type implementing AsyncRPCClient. For example,

#[essrpc(async)]
pub trait Foo {
fn bar(&self, a: String, b: i32) -> Result<String, SomeError>;
}

Would generate a FooAsync trait with a bar method returning Box<Future<Item=String, Error=SomeError>> and a FooAsyncRPCClient struct implementing both FooAsync and AsyncRPCClient.