Getting Started with Swoole for IoT Development: Installation, TCP & WebSocket Servers, Async I/O, and Coroutines

Swoole is an asynchronous, high‑performance network communication framework for PHP that supports TCP, UDP, WebSocket, coroutine, asynchronous file I/O, timers, and is well‑suited for IoT development.

1. Install the Swoole extension

Swoole requires PHP 7 or higher. You can install it via PECL: pecl install swoole Or compile from source:

git clone https://github.com/swoole/swoole-src.git
cd swoole-src
phpize
./configure
make
sudo make install

After installation, add the extension to your php.ini: extension=swoole.so 2. Create a TCP Server

The following code creates a simple TCP server that listens on 127.0.0.1:9501 and handles connect, receive, and close events:

$server = new \Swoole\Server('127.0.0.1', 9501);
$server->on('connect', function ($server, $fd) {
    echo "Client: Connect.
";
});
$server->on('receive', function ($server, $fd, $from_id, $data) {
    $server->send($fd, 'Swoole: ' . $data);
});
$server->on('close', function ($server, $fd) {
    echo "Client: Close.
";
});
$server->start();

3. Create a WebSocket Server

Swoole also supports the WebSocket protocol. The code below creates a WebSocket server on the same address and port, handling open, message, and close events:

$server = new \Swoole\Websocket\Server('127.0.0.1', 9501);
$server->on('open', function ($server, $request) {
    echo "Client: Connect.
";
});
$server->on('message', function ($server, $frame) {
    $server->push($frame->fd, 'Swoole: ' . $frame->data);
});
$server->on('close', function ($server, $fd) {
    echo "Client: Close.
";
});
$server->start();

4. Use Asynchronous I/O

Swoole provides asynchronous file operations. The example reads a file without blocking the event loop:

$file = '/path/to/file';
\Swoole\Async::readFile($file, function ($filename, $content) {
    echo $content;
});

5. Use Coroutines

Coroutines allow writing asynchronous code in a synchronous style. The following snippet creates a coroutine that opens a TCP client, sends a message, and receives a response:

go(function () {
    $client = new \Swoole\Coroutine\Client(SWOOLE_SOCK_TCP);
    $client->connect('127.0.0.1', 9501);
    $client->send('Hello, Swoole!');
    $response = $client->recv();
    echo $response;
});

These steps demonstrate how to set up Swoole for IoT projects, covering installation, server creation, asynchronous I/O, and coroutine usage.