EventController.php

<?php

namespace app\controllers;

use app\classes\SSE;
use app\helpers\Notification;
use Yii;
use yii\web\Controller;

/**
 * Description of EventController
 *
 * @author Misbahul D Munir <[email protected]>
 * @since 1.0
 */
class EventController extends Controller
{

    public function actionIndex()
    {
        $sse = new SSE();
        $checkTime = Yii::$app->request->headers->get('last-event-id', 0);
        $userId = Yii::$app->user->id;

        $cx = mt_rand(5, 10);
        $sse->id(time());
        while (true) {
            $data = Notification::getNotif($userId, $checkTime);
            if (count($data)) {
                $sse->event('notify', $data);
            }

            // kirimkan id
            $cx--;
            if ($cx <= 0) {
                $cx = mt_rand(5, 10);
                $sse->id(time());
                $sse->event('test', ['a'=>'oke']);
            }
            $checkTime = time();
            $sse->flush();
            sleep(1);
        }
        exit();
    }
}

SSE.php

<?php

namespace app\classes;

/**
 * Description of SSE
 *
 * @author Misbahul D Munir <[email protected]>
 * @since 1.0
 */
class SSE
{
    /**
     *
     * @var boolean
     */
    private $_headerSent;

    private function sendHeader()
    {
        if (!$this->_headerSent && !headers_sent()) {
            $this->_headerSent = true;
            header("Content-Type: text/event-stream");
            header('Cache-Control: no-cache');
        }
    }

    public function event($name, $data = null)
    {
        $this->sendHeader();
        echo "event: {$name}\n";
        if ($data !== null) {
            $this->sendData($data);
        }
        echo "\n";
    }

    protected function sendData($data)
    {
        $messages = explode("\n", json_encode($data));
        foreach ($messages as $message) {
            echo "data: {$message}\n";
        }
    }

    public function message($data)
    {
        $this->sendHeader();
        $this->sendData($data);
        echo "\n";
    }

    public function id($id, $data = '')
    {
        $this->sendHeader();
        echo "id: {$id}\n";
        $this->sendData($data);
        echo "\n";
    }

    public function retry($time)
    {
        $this->sendHeader();
        echo "retry: {$time}\n\n";
    }

    public function flush()
    {
        $this->sendHeader();
        while (ob_get_level() > 0) {
            ob_end_flush();
        }
        flush();
        // break the loop if the client aborted the connection (closed the page)
        if (connection_aborted()) {
            exit();
        }
    }
}