Playing with event dispatcher and Silex. Sending logs to a remote server.


Today I continue playing with event dispatcher and Silex. Now I want to send a detailed log of our Kernel events to a remote server. We can do it something similar with Monolog, but I want to implement one working example hacking a little bit the event dispatcher. Basically we’re going to create one Logger class (implementing PSR-3 of course)

namespace G;

use Psr\Log\LoggerInterface;
use Psr\Log\LogLevel;

class Logger implements LoggerInterface
{
    private $socket;

    public function __construct($socket)
    {
        $this->socket = $socket;
    }

    function __destruct()
    {
        @fclose($this->socket);
    }

    public function emergency($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::EMERGENCY);
    }

    public function alert($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::ALERT);
    }

    public function critical($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::CRITICAL);
    }

    public function error($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::ERROR);
    }

    public function warning($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::WARNING);
    }

    public function notice($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::NOTICE);
    }

    public function info($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::INFO);
    }

    public function debug($message, array $context = array())
    {
        $this->sendLog($message, $context, LogLevel::DEBUG);
    }

    public function log($level, $message, array $context = array())
    {
        $this->sendLog($message, $context, $level);
    }

    private function sendLog($message, array $context = array(), $level = LogLevel::INFO)
    {
        $data = serialize([$message, $context, $level]);
        @fwrite($this->socket, "{$data}\n");
    }
}

As you can see our Logger class send logs to a remote server, with a socket passed within the constructor.
We also need one Service Provider called LoggerServiceProvider to integrate our Logger instance into our Silex application.

namespace G;

use Silex\Application;
use Silex\ServiceProviderInterface;

class LoggerServiceProvider implements ServiceProviderInterface
{
    private $socket;

    public function __construct($socket)
    {
        $this->socket = $socket;
    }

    public function register(Application $app)
    {
        $app['remoteLogger'] = $app->share(
            function () use ($app) {
                return new Logger($this->socket);
            }
        );
    }

    public function boot(Application $app)
    {
    }
}

And now the last part is our Silex application:

use G\LoggerServiceProvider;
use G\Silex\Application;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel;
use Symfony\Component\HttpKernel\Event;

$app = new Application();
$app->register(new LoggerServiceProvider(stream_socket_client('tcp://localhost:4000')));

$app->on(HttpKernel\KernelEvents::REQUEST, function (Event\GetResponseEvent $event) use ($app) {
        $app->getLogger()->info($event->getName());
    }
);

$app->on(HttpKernel\KernelEvents::CONTROLLER, function (Event\FilterControllerEvent $event) use ($app) {
        $app->getLogger()->info($event->getName());
    }
);

$app->on(HttpKernel\KernelEvents::TERMINATE, function (Event\PostResponseEvent $event) use ($app) {
        $app->getLogger()->info($event->getName());
    }
);

$app->on(HttpKernel\KernelEvents::EXCEPTION, function (Event\GetResponseForExceptionEvent $event) use ($app) {
        $app->getLogger()->critical($event->getException()->getMessage());
    }
);

$app->get('/', function () {
    return 'Hello';
});

$app->run();

As we can see the event dispacher send each event to a remote server (in this example: tcp://localhost:4000). Now we only need a tcp server to handle those sockets. We can use different tools and libraries to do that. In this example we’re going to use React.

use React\EventLoop\Factory;
use React\Socket\Server;

$loop   = Factory::create();
$socket = new Server($loop);

$socket->on('connection', function (\React\Socket\Connection $conn){
    $unique = uniqid();
    $conn->on('data', function ($data) use ($unique) {
            list($message, $context, $level) = \unserialize($data);
            echo date("d/m/Y H:i:s")."::{$level}::{$unique}::{$message}" . PHP_EOL;
        });
});

echo "Socket server listening on port 4000." .PHP_EOL;
echo "You can connect to it by running: telnet localhost 4000" . PHP_EOL;

$socket->listen(4000);
$loop->run();

Now we only need to start our servers:
our silex one

php -S 0.0.0.0:8080 -t www

and the tcp server

php app/server.php

One screencast showing the prototype in action:

You can see the full code in my github account.

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About Gonzalo Ayuso

Web Architect specialized in Open Source technologies. PHP, Python, JQuery, Dojo, PostgreSQL, CouchDB and node.js but always learning.

Posted on October 21, 2013, in php, silex, Symfony, Technology and tagged , . Bookmark the permalink. 3 Comments.

  1. “class Logger implements LoggerInterface”

    Extend abstract logger for much cleaner solution…

    • I try to avoid to extend abstract classes as a plague. I’ve used a lot of abstract classes in the past, but nowadays I realized that they normally turn into a hodgepodge, violating the single responsibility principle. As a general rule I prefer to work with interfaces instead of abstract classes (and simple inheritance). In fact I prefer to work with traits than extending abstract classes.

  1. Pingback: Дайджест интересных новостей и материалов из мира PHP (20 октября — 10 ноября 2013) | Juds

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