Add examples on how to use the library

pull/1/head
Daniel Abramov 8 years ago
parent dbd9c7775b
commit 65aac6664e
  1. 116
      examples/client.rs
  2. 123
      examples/server.rs

@ -0,0 +1,116 @@
//! A simple example of hooking up stdin/stdout to a WebSocket stream.
//!
//! This example will connect to a server specified in the argument list and
//! then forward all data read on stdin to the server, printing out all data
//! received on stdout.
//!
//! Note that this is not currently optimized for performance, especially around
//! buffer management. Rather it's intended to show an example of working with a
//! client.
//!
//! You can use this example together with the `server` example.
extern crate futures;
extern crate tokio_core;
extern crate tokio_tungstenite;
extern crate tungstenite;
extern crate url;
use std::env;
use std::io::{self, Read, Write};
use std::net::ToSocketAddrs;
use std::thread;
use futures::sync::mpsc;
use futures::{Future, Sink, Stream};
use tokio_core::net::TcpStream;
use tokio_core::reactor::Core;
use tokio_tungstenite::ClientHandshakeExt;
use tungstenite::handshake::client::{ClientHandshake, Request};
use tungstenite::protocol::Message;
fn main() {
// Specify the server address to which the client will be connecting.
let connect_addr = env::args().nth(1).unwrap_or_else(|| {
panic!("this program requires at least one argument")
});
// Get a first IP address of the server from the server URL.
let url = url::Url::parse(&connect_addr).unwrap();
let addr = url.to_socket_addrs().unwrap().next().unwrap();
// Create the event loop and initiate the connection to the remote server.
let mut core = Core::new().unwrap();
let handle = core.handle();
let tcp = TcpStream::connect(&addr, &handle);
// Right now Tokio doesn't support a handle to stdin running on the event
// loop, so we farm out that work to a separate thread. This thread will
// read data from stdin and then send it to the event loop over a standard
// futures channel.
let (stdin_tx, stdin_rx) = mpsc::channel(0);
thread::spawn(|| read_stdin(stdin_tx));
let stdin_rx = stdin_rx.map_err(|_| panic!()); // errors not possible on rx
// After the TCP connection has been established, we set up our client to
// start forwarding data.
//
// First we do a WebSocket handshake on a TCP stream, i.e. do the upgrade
// request.
//
// Half of the work we're going to do is to take all data we receive on
// stdin (`stdin_rx`) and send that along the WebSocket stream (`sink`).
// The second half is to take all the data we receive (`stream`) and then
// write that to stdout. Currently we just write to stdout in a synchronous
// fashion.
//
// Finally we set the client to terminate once either half of this work
// finishes. If we don't have any more data to read or we won't receive any
// more work from the remote then we can exit.
let mut stdout = io::stdout();
let client = tcp.and_then(|stream| {
let req = Request { url: url };
ClientHandshake::<TcpStream>::new_async(stream, req).and_then(|ws_stream| {
println!("WebSocket handshake has been successfully completed");
// `sink` is the stream of messages going out.
// `stream` is the stream of incoming messages.
let (sink, stream) = ws_stream.split();
// We forward all messages, composed out of the data, entered to
// the stdin, to the `sink`.
let send_stdin = stdin_rx.forward(sink);
let write_stdout = stream.for_each(|message| {
stdout.write_all(&message.into_data()).unwrap();
Ok(())
});
// Wait for either of futures to complete.
send_stdin.map(|_| ())
.select(write_stdout.map(|_| ()))
.then(|_| Ok(()))
}).map_err(|e| {
println!("Error during the websocket handshake occurred: {}", e);
io::Error::new(io::ErrorKind::Other, e)
})
});
// And now that we've got our client, we execute it in the event loop!
core.run(client).unwrap();
}
// Our helper method which will read data from stdin and send it along the
// sender provided.
fn read_stdin(mut tx: mpsc::Sender<Message>) {
let mut stdin = io::stdin();
loop {
let mut buf = vec![0; 1024];
let n = match stdin.read(&mut buf) {
Err(_) |
Ok(0) => break,
Ok(n) => n,
};
buf.truncate(n);
tx = tx.send(Message::binary(buf)).wait().unwrap();
}
}

@ -0,0 +1,123 @@
//! A chat server that broadcasts a message to all connections.
//!
//! This is a simple line-based server which accepts WebSocket connections,
//! reads lines from those connections, and broadcasts the lines to all other
//! connected clients.
//!
//! You can test this out by running:
//!
//! cargo run --example server
//!
//! And then in another window run:
//!
//! cargo run --example client ws://127.0.0.1:12345/
//!
//! You can run the second command in multiple windows and then chat between the
//! two, seeing the messages from the other client as they're received. For all
//! connected clients they'll all join the same room and see everyone else's
//! messages.
extern crate futures;
extern crate tokio_core;
extern crate tokio_tungstenite;
extern crate tungstenite;
use std::cell::RefCell;
use std::collections::HashMap;
use std::env;
use std::io::{Error, ErrorKind};
use std::rc::Rc;
use futures::stream::Stream;
use futures::{Future};
use tokio_core::net::{TcpListener, TcpStream};
use tokio_core::reactor::Core;
use tokio_tungstenite::ServerHandshakeExt;
use tungstenite::handshake::server::ServerHandshake;
use tungstenite::protocol::Message;
fn main() {
let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
let addr = addr.parse().unwrap();
// Create the event loop and TCP listener we'll accept connections on.
let mut core = Core::new().unwrap();
let handle = core.handle();
let socket = TcpListener::bind(&addr, &handle).unwrap();
println!("Listening on: {}", addr);
// This is a single-threaded server, so we can just use Rc and RefCell to
// store the map of all connections we know about.
let connections = Rc::new(RefCell::new(HashMap::new()));
let srv = socket.incoming().for_each(|(stream, addr)| {
// We have to clone both of these values, because the `and_then`
// function billow constructs a new future, `and_then` requires
// `FnOnce`, so we construct a move closure to move the
// environment inside the future (AndThen future may overlive our
// `for_each` future).
let connections_inner = connections.clone();
let handle_inner = handle.clone();
ServerHandshake::<TcpStream>::new_async(stream).and_then(move |ws_stream| {
println!("New WebSocket connection: {}", addr);
// Create a channel for our stream, which other sockets will use to
// send us messages. Then register our address with the stream to send
// data to us.
let (tx, rx) = futures::sync::mpsc::unbounded();
connections_inner.borrow_mut().insert(addr, tx);
// Let's split the WebSocket stream, so we can work with the
// reading and writing halves separately.
let (sink, stream) = ws_stream.split();
// Whenever we receive a message from the client, we print it and
// send to other clients, excluding the sender.
let connections = connections_inner.clone();
let ws_reader = stream.for_each(move |message: Message| {
println!("Received a message from {}: {}", addr, message);
// For each open connection except the sender, send the
// string via the channel.
let mut conns = connections.borrow_mut();
let iter = conns.iter_mut()
.filter(|&(&k, _)| k != addr)
.map(|(_, v)| v);
for tx in iter {
tx.send(message.clone()).unwrap();
}
Ok(())
});
// Whenever we receive a string on the Receiver, we write it to
// `WriteHalf<WebSocketStream>`.
let ws_writer = rx.fold(sink, |mut sink, msg| {
use futures::Sink;
sink.start_send(msg).unwrap();
Ok(sink)
});
// Now that we've got futures representing each half of the socket, we
// use the `select` combinator to wait for either half to be done to
// tear down the other. Then we spawn off the result.
let connection = ws_reader.map(|_| ()).map_err(|_| ())
.select(ws_writer.map(|_| ()).map_err(|_| ()));
handle_inner.spawn(connection.then(move |_| {
connections_inner.borrow_mut().remove(&addr);
println!("Connection {} closed.", addr);
Ok(())
}));
Ok(())
}).map_err(|e| {
println!("Error during the websocket handshake occurred: {}", e);
Error::new(ErrorKind::Other, e)
})
});
// Execute server.
core.run(srv).unwrap();
}
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