php中Workerman框架是什么？

<?php

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

use Workerman\Worker;

// 创建一个Websocket服务器

$ws_worker = new Worker("websocket://0.0.0.0:2346");

$ws_worker->count = 4;

// 在新连接到来时发出

$ws_worker->onConnect = function($connection)

{

    echo "New connection\n";

 };

// 接收数据时发出

$ws_worker->onMessage = function($connection, $data)

{

    // Send hello $data

    $connection->send('hello ' . $data);

};

// 连接关闭时发出

$ws_worker->onClose = function($connection)

{

    echo "Connection closed\n";

};

// 运行worker

Worker::runAll();