In today's information age, online voting systems have become an indispensable part of elections, surveys and other activities. Compared with traditional voting methods, the online voting system is not only easy to operate, but also fast and can realize functions such as real-time statistics.

This article will introduce how to use PHP's Workerman framework to build an online voting system based on the WebSocket protocol. At the same time, specific code examples will be given for readers' reference.

1. What is Workerman?

Workerman is a high-performance, open source PHP asynchronous framework. It is based on event-driven ideas and can easily implement long-connection applications, such as WebSocket, instant messaging and other applications.

Workerman supports protocols such as TCP, UDP and HTTP, and has the characteristics of high concurrency and low memory consumption. Compared with traditional web applications, Workerman has stronger real-time performance and stability, so it is suitable for application scenarios such as online games, chat rooms, barrage, and message push.

2. Build a WebSocket server

Before we begin, we need to ensure that the PHP environment has been installed and the Workerman framework has been installed. For specific installation procedures, please refer to the official documentation.

Next, we need to create a new PHP file to start the WebSocket server and listen to the messages sent by the client. Suppose we open the WebSocket service on the 8080 port of the local 127.0.0.1, the code is as follows:

<?php
require_once __DIR__ . '/vendor/autoload.php';

use WorkermanWorker;
use WorkermanWebServer;
use WorkermanProtocolsWebsocket;

$ws_worker = new Worker('websocket://127.0.0.1:8080');
$ws_worker->count = 1;

$ws_worker->onWorkerStart = function() {
    echo "WebSocket server started
";
};

$ws_worker->onConnect = function($connection) {
    echo "New connection established: {$connection->id}
";
};

$ws_worker->onMessage = function($connection, $data) {
    echo "Received a message from {$connection->id}: $data
";
};

Worker::runAll();

In the above code, we use Workerman's Worker Class to open a WebSocket server and listen on the 8080 port of 127.0.0.1. The count attribute specifies the number of processes started. When a client connects, the onConnect callback function will be triggered; when a client sends a message, the onMessage callback function will be triggered. We can handle client connections and messages in these two callback functions.

3. Implementing an online voting system

In the voting system, we need to support multiple users voting at the same time, and we need to display the voting results in real time. In order to implement such functionality, we need to use PHP's shared memory mechanism and the JSON format to pass data between the client and server.

First, we need to define an associative array $votes on the server side to store the number of votes for each voting option. Each time we receive a voting request from the client, we will add one to the number of votes for the corresponding option, and the number of votes for different options will be stored in different array elements.

<?php
// ...

$votes = [
    'Option 1' => 0,
    'Option 2' => 0,
    'Option 3' => 0,
];

$ws_worker->onMessage = function($connection, $data) use ($votes) {
    $data = json_decode($data, true);
    if (!isset($data['option']) || !isset($votes[$data['option']])) {
        // 投票選項不存在或者為空
        $connection->send(json_encode([
            'code' => 400,
            'message' => 'Invalid option'
        ]));
        return;
    }
    $votes[$data['option']]++;

    // 廣播投票結果
    broadcast(json_encode([
        'code' => 200,
        'message' => 'Vote successfully',
        'data' => $votes
    ]));
};

function broadcast($data) {
    global $ws_worker;
    foreach ($ws_worker->connections as $connection) {
        $connection->send($data);
    }
}

In the above code, we use PHP’s global keyword to introduce the $ws_worker object into the broadcast function. In each After voting, the voting results are broadcast to all connected clients in JSON format. In the above code, we also define a broadcast function to send messages to all connected clients.

Next, we need to implement the voting function of the client. In HTML pages, we can create WebSocket objects through JavaScript code for real-time communication with the server.

<!DOCTYPE html>
<html>
<head>
    <title>WebSocket - Online Voting System</title>
</head>
<body>
    <h1>Online Voting System</h1>
    <p>Vote for your favorite option:</p>
    <form id="form">
        <input type="radio" name="option" value="Option 1">Option 1<br>
        <input type="radio" name="option" value="Option 2">Option 2<br>
        <input type="radio" name="option" value="Option 3">Option 3<br>
        <input type="submit" value="Vote">
    </form>

    <ul id="result">
        <li>Option 1: <span id="vote1"></span></li>
        <li>Option 2: <span id="vote2"></span></li>
        <li>Option 3: <span id="vote3"></span></li>
    </ul>

    <script type="text/javascript">
        var ws = new WebSocket('ws://127.0.0.1:8080');

        ws.onopen = function() {
            console.log('WebSocket connected');
        }

        ws.onmessage = function(event) {
            var data = JSON.parse(event.data);
            if (data.code === 200) {
                // 投票成功
                updateVotes(data.data);
            } else {
                // 投票失敗
                console.error(data.message);
            }
        }

        function updateVotes(votes) {
            document.querySelector('#vote1').innerHTML = votes['Option 1'];
            document.querySelector('#vote2').innerHTML = votes['Option 2'];
            document.querySelector('#vote3').innerHTML = votes['Option 3'];
        }

        var form = document.querySelector('#form');
        form.addEventListener('submit', function(event) {
            event.preventDefault();
            var option = document.querySelector('input[name="option"]:checked');
            if (!option) {
                console.error('Please choose an option');
                return;
            }
            var data = {
                option: option.value
            };
            ws.send(JSON.stringify(data));
            option.checked = false;
        });
    </script>
</body>
</html>

In the above code, we use the onopen and onmessage two callback functions of the WebSocket object, which are used after the connection is established. Output logs and receive messages from the server. In the form, we use the submit event to capture the user's voting behavior and send the voting information to the server through the WebSocket object. Each time we receive voting results from the server, we update the voting data in the HTML page through the updateVotes function.

4. Summary

This article introduces how to use PHP's Workerman framework to implement an online voting system based on the WebSocket protocol, and gives specific code examples. Through studying this article, readers should have a deeper understanding and mastery of the Workerman framework, shared memory mechanism, WebSocket protocol and other knowledge.

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