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async-tungstenite/examples/split-client.rs

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//! 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.
use std::env;
use futures::{SinkExt, StreamExt};
use log::*;
use tungstenite::protocol::Message;
use async_std::prelude::*;
use async_std::io;
use async_std::task;
use async_tungstenite::connect_async;
async fn run() {
let _ = env_logger::try_init();
// 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"));
let url = url::Url::parse(&connect_addr).unwrap();
// Spawn a new task that will read data from stdin and then send it to the event loop over a
// standard futures channel.
let (stdin_tx, mut stdin_rx) = futures::channel::mpsc::unbounded();
task::spawn(read_stdin(stdin_tx));
// 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 (ws_stream, _) = connect_async(url).await.expect("Failed to connect");
let (mut ws_tx, mut ws_rx) = ws_stream.split();
info!("WebSocket handshake has been successfully completed");
while let Some(msg) = stdin_rx.next().await {
ws_tx.send(msg).await.expect("Failed to send request");
if let Some(msg) = ws_rx.next().await {
let msg = msg.expect("Failed to get response");
stdout.write_all(&msg.into_data()).await.unwrap();
}
}
}
// Our helper method which will read data from stdin and send it along the
// sender provided.
async fn read_stdin(tx: futures::channel::mpsc::UnboundedSender<Message>) {
let mut stdin = io::stdin();
loop {
let mut buf = vec![0; 1024];
let n = match stdin.read(&mut buf).await {
Err(_) | Ok(0) => break,
Ok(n) => n,
};
buf.truncate(n);
tx.unbounded_send(Message::binary(buf)).unwrap();
}
}
fn main() {
task::block_on(run())
}