TCP sockets

In PandJS, std:net module provides an asynchronous network API for creating stream-based TCP connections.

TCP echo client

In this code below, client will wait for data from the server and will send this data back.

import { Socket } from 'std:net';

const socket = new Socket();

socket.ondata = (chunk) => {
  console.log(chunk.toString('utf8'));
  socket.write(chunk);
}

socket.onerror = (err) => {
  console.log("Got error:", err);
}

socket.onclose = () => {
  console.log("connection closed?", socket.destroyed);
}

await socket.connect('127.0.0.1', 8000);

TCP echo server

import { Server } from 'std:net';

const server = new Server();

server.onconnection = function(socket) {
  socket.ondata = (chunk) => {
    console.log(chunk.toString('utf8'));
    socket.write(chunk);
    socket.shutdown();
  };

  socket.onerror = (err) => {
    console.log(err);
  }

  socket.onclose = () => {
    console.log("connection closed");
  };
}

server.listen(5000);
console.log(`Starting server on port: ${server.port}`);

Closing TCP connections

There is 2 ways to close connection:

Graceful with socket.shutdown - prefered way of closing connections.
```
socket.shutdown();
```
Aggresive with socket.destroy - useful during errors and timeouts.
```
socket.destroy();
```