How Swoole supports the broadcast function of Websocket

With the continuous development of Internet technology, Websocket has become a very popular communication protocol. As a high-performance network communication framework, Swoole has also begun to strongly support Websocket. This article will introduce in detail how Swoole supports the broadcast function of Websocket.

Characteristics of Websocket communication protocol

Before we talk about how Swoole supports the broadcast function of Websocket, let’s briefly introduce the characteristics of Websocket communication protocol.

Websocket is a TCP-based protocol and a two-way communication protocol. Compared with the HTTP protocol, it is more suitable for real-time communication scenarios. The connection process of the Websocket protocol is similar to the HTTP protocol. After the connection is successful, the client and the server can send messages freely and disconnect at any time.

In the Websocket communication protocol, there are three commonly used message types, namely text messages, binary messages and Ping/Pong messages. Among them, text messages and binary messages are ordinary data transmission, while Ping/Pong messages are used to detect whether the connection is maintained.

Because the Websocket communication protocol is more suitable for real-time communication scenarios, it is often necessary to support the broadcast function during the implementation process.

Swoole’s support for Websocket

Swoole, as a high-performance network communication framework, began to strongly support the Websocket communication protocol after version 0.4.0. Currently, the Websocket versions supported by Swoole include the following:

1. RFC 6455 (supports handshake process and all standard data frames).
2. Hybi-10 (except closing frame).

Swoole's support for Websocket includes the following parts:

1. Websocket server: Provides Websocket server program, handles Websocket handshake and data sending, etc.
2. Websocket client: Provides Websocket client program, supports Websocket connection and data sending, etc.
3. Extended command line tools: Provides a command line tool swoole similar to nc, which can be used to test the Websocket server and client.
4. Support broadcast: Support Websocket broadcast function, which can broadcast messages between multiple Websocket clients.

Next, we will mainly introduce how Swoole supports the broadcast function of Websocket.

Swoole's Websocket broadcast function

In order to implement the Websocket broadcast function, we need to first implement a Websocket server and connect multiple Websocket clients to the server. Then, implement the broadcast function in the server to send the message to all clients connected to the server.

Now, let’s take a look at the specific implementation steps.

1. Implementing the Websocket server

First, we need to implement a Websocket server. For specific implementation steps, please refer to the sample code in the official documentation.

When implementing the Websocket server, you need to pay attention to the following points:

1. When listening for client connections, you need to set $flags to SWOOLE_WEBSOCKET, indicating the use of the Websocket protocol.
2. When receiving client messages, you need to use the onMessage callback function and determine the message type for corresponding processing.

The sample code is as follows:

$server = new SwooleWebsocketServer("127.0.0.1", 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP | SWOOLE_SSL);
$server->set([
    'ssl_cert_file' => '/your_server_path/ssl.crt',
    'ssl_key_file' => '/your_server_path/ssl.key',
]);

$server->on('open', function (SwooleWebSocketServer $server, $request) {
    echo "client {$request->fd} connected
";
});

$server->on('message', function (SwooleWebSocketServer $server, $frame) {
    echo "received message: {$frame->data}
";
    // 进行消息处理
});

$server->on('close', function (SwooleWebSocketServer $server, $fd) {
    echo "client {$fd} closed
";
});

$server->start();

2. Connect multiple Websocket clients

Next, we need to connect multiple Websocket clients to On the server. For specific implementation steps, you can also refer to the sample code in the official documentation.

The sample code is as follows:

var ws = new WebSocket("ws://127.0.0.1:9501");

ws.onopen = function(event) {
    ws.send("Hello, Websocket!");
};

ws.onmessage = function(event) {
    console.log("received message: " + event.data);
};

ws.onclose = function(event) {
    console.log("connection closed");
};

3. Implementing Websocket broadcast

Finally, we need to implement the Websocket broadcast function on the server side, that is, sending messages to all connections client to the server.

The specific implementation steps are as follows:

1. Save the $fd of all clients connected to the server.
2. When a message is received, send the message to all saved clients' $fd.

The sample code is as follows:

$server = new SwooleWebsocketServer("127.0.0.1", 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP | SWOOLE_SSL);

$clients = [];

$server->on('open', function (SwooleWebSocketServer $server, $request) use (&$clients) {
    echo "client {$request->fd} connected
";
    $clients[] = $request->fd;
});

$server->on('message', function (SwooleWebSocketServer $server, $frame) use (&$clients) {
    echo "received message: {$frame->data}
";
    foreach ($clients as $client) {
        $server->push($client, $frame->data);
    }
});

$server->on('close', function (SwooleWebSocketServer $server, $fd) use (&$clients) {
    echo "client {$fd} closed
";
    $index = array_search($fd, $clients);
    if ($index !== false) {
        unset($clients[$index]);
    }
});

$server->start();

So far, we have successfully implemented Swoole's broadcast function for Websocket. Through the above implementation, the message broadcast function can be implemented between multiple Websocket clients.

Summary

Websocket communication protocol is a very popular real-time communication protocol, and Swoole, as a high-performance network communication framework, has also begun to strongly support Websocket. This article mainly introduces how Swoole supports the broadcast function of Websocket. I hope it will be helpful to everyone.

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