examples/fidl/echo_server_rust/src/main.rs

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#![deny(warnings)]

extern crate failure;
extern crate fidl;
extern crate fuchsia_app;
extern crate futures;
extern crate tokio_core;

// The `failure` crate provides an error trait called `Fail`,
// as well as a standard dynamically-dispatched `Error` type.
use failure::{Error, ResultExt};

// Include the generated FIDL bindings for the `Echo` service.
extern crate garnet_examples_fidl_services;
use garnet_examples_fidl_services::Echo;

use fuchsia_app::server::ServicesServer;
use futures::future;
use tokio_core::reactor;

// `EchoServer` is a zero-sized type that implements the `Echo::Server` trait.
struct EchoServer;

impl Echo::Server for EchoServer {
    // The concrete type returned by the `echo_string` function.
    // This type must implement `Future<Item = Option<String>, Error = fidl::CloseChannel>`.
    type EchoString = future::FutureResult<Option<String>, fidl::CloseChannel>;

    fn echo_string(&mut self, value: Option<String>) -> Self::EchoString
    {
        future::ok(value)
    }
}

fn main() {
    if let Err(e) = main_res() {
        eprintln!("Error running Rust echo server: {:?}", e);
    }
}

fn main_res() -> Result<(), Error> {
    // Create a new reactor core for handling IO events.
    let mut core = reactor::Core::new().context("Unable to create core")?;
    let handle = core.handle();

    // Create a service provider which will provide a new EchoServer
    // instance upon receiving a `connect_to_service` request.
    let services_server =
        ServicesServer::new()
            .add_service(|| Echo::Dispatcher(EchoServer))
            .start(&handle)
            .context("Error configuring services server")?;

    // Run the server on the reactor core.
    // The server is an empty `Future` that can return `fidl::Error`.
    Ok(core.run(services_server).context("Error running server")?)
}