Ratchet WebSocket Library for PHP: Creating Real-Time on Your Website

What is WebSocket and why do you need the Ratchet library for PHP?

WebSocket is a protocol that provides a persistent two-way connection between a client (browser) and a server. Unlike classic HTTP, where only the client initiates requests, WebSocket allows the server to send data instantly without waiting for a request. This is an ideal solution for chats, real-time notifications, online games, trackers, and any applications where low latency is important.

Standard PHP does not have built-in WebSocket support, but the Ratchet library (using the ReactPHP component) fills this gap. Ratchet is an asynchronous library that allows you to run a WebSocket server directly from PHP, handling multiple connections simultaneously without blocking.

Key Features of Ratchet

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• Asynchronous — based on ReactPHP, does not block the thread while waiting for data.
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• Protocol Support — WebSocket (RFC 6455), as well as HTTP components (for hybrid applications).
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• Simplicity — minimal code to run a server.
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• Scalability — can be combined with ZeroMQ or Redis for cluster operation.
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• Compatibility — works with any modern browser via the built-in WebSocket object.
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Installing Ratchet

Installation is done via Composer. Open a terminal in the project root and run:

composer require cboden/ratchet

After installation, all dependencies including ReactPHP will appear in the vendor folder.

Creating a Simple WebSocket Server with Ratchet

Let's create a file server.php:

<?php\nrequire 'vendor/autoload.php';\n\nuse Ratchet\\MessageComponentInterface;\nuse Ratchet\\ConnectionInterface;\nuse Ratchet\\Server\\IoServer;\nuse Ratchet\\Http\\HttpServer;\nuse Ratchet\\WebSocket\\WsServer;\n\nclass Chat implements MessageComponentInterface {\n    protected $clients;\n\n    public function __construct() {\n        $this->clients = new \\SplObjectStorage;\n    }\n\n    public function onOpen(ConnectionInterface $conn) {\n        $this->clients->attach($conn);\n        echo "New connection: {$conn->resourceId}\\n";\n    }\n\n    public function onMessage(ConnectionInterface $from, $msg) {\n        foreach ($this->clients as $client) {\n            if ($from !== $client) {\n                $client->send($msg);\n            }\n        }\n    }\n\n    public function onClose(ConnectionInterface $conn) {\n        $this->clients->detach($conn);\n        echo "Disconnection: {$conn->resourceId}\\n";\n    }\n\n    public function onError(ConnectionInterface $conn, \\Exception $e) {\n        echo "Error: {$e->getMessage()}\\n";\n        $conn->close();\n    }\n}\n\n$server = IoServer::factory(\n    new HttpServer(\n        new WsServer(\n            new Chat()\n        )\n    ),\n    8080\n);\n\necho "Server started on port 8080\\n";\n$server->run();

Code Explanation

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• Chat — a class implementing MessageComponentInterface. In onOpen we save the connection, in onMessage we broadcast the message to everyone except the sender.
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• IoServer::factory — creates a server based on ReactPHP. We wrap our component in WsServer (for WebSocket) and HttpServer (for compatibility with HTTP requests).
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• The server listens on port 8080. Start it with the command: php server.php.
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Client Side (JavaScript)

Create an HTML file client.html:

<!DOCTYPE html>\n<html>\n<head>\n    <title>WebSocket Chat</title>\n    <script>\n        const ws = new WebSocket('ws://localhost:8080');\n\n