Handle Facebook API real time updates using PHP

Facebook Graph API offers a cool feature for applications, real time updates, to enable your application to subscribe to changes in data. Using the API can improve dramatically the reliability of your application and decrease the load time. Whenever a subscribed change occurs, Facebook makes a HTTP post request to the URL address you specify, with a list of changes. Please note that only the changed properties are sent, not the actual data. You'll have to query the data using Facebook APIs (Graph or FQL) in order to get the changes.
Real time updates are easy to configure, the Facebook documentation is strait forward: https://developers.facebook.com/docs/reference/api/realtime/
However, you have to handle the post data sent by Facebook; on the developers website you can find a Python sample application. A lot of Facebook developers are asking for a PHP version.
I recently built a simple PHP to handle Facebook post requests which works great for a large volume of data. The script is also verifying the request by validating the X_HUB_SIGNATURE header and making sure is coming from Facebook.
Here is the code:

if($_SERVER['REQUEST_METHOD'] == 'GET')
{
    if(array_key_exists('hub_mode', $_GET)
        && array_key_exists('hub_challenge', $_GET)
        && array_key_exists('hub_verify_token', $_GET)
        && $_GET['hub_mode'] == 'subscribe'
        && $_GET['hub_verify_token'] == FB_REALTIME_API_SECRET)
        die($_GET['hub_challenge']);
}
elseif($_SERVER['REQUEST_METHOD'] == 'POST')
{
    $payload = file_get_contents('php://input');
    if(!empty($payload)
        && array_key_exists($_SERVER, 'HTTP_X_HUB_SIGNATURE')
        && $_SERVER['HTTP_X_HUB_SIGNATURE'] == 'sha1='
              .hash_hmac('sha1', $payload, FB_APP_SECRET))
        // Do your thing - for example cache the payload on a database for later processing
}

Happy coding!

Facebook Developers Workd HACK in Barcelona - Best Twilio API integration prize

A team of geeks from Cossette (me and three colleagues, Maxime Gagné, Ugo Tessier and Doruk Vardaryildiz) participated to an international event organized by Facebook in Barcelona, Spain: Developers World HACK.
Facebook Developer HACKs are day-long coding events where developers are given time to work on new social apps, solo or in groups, with Facebook engineers on hand to support and answer questions. It is also a wonderful opportunity to meet with other developers from around the world.
Our experts have already developed tons of Facebook applications and platforms, so we were confident that we would produce a spectacular application during the event. Everybody worked hard and quickly, so it was really intense, but at the same time we had a lot of fun. It was a real geek party: food, nice ambient music and a lot of code, working really hard at the end to put everything together, than present what we accomplished during the day.
We were very pleased to be awarded one of the seven prizes. We won the best Twilio API integration award. Twilio powers the future of business communications, enabling phones, VoIP, and messaging to be embedded into web, desktop, and mobile software.
More details on the SildeShare presentation (in french): http://www.slideshare.net/MarianBorca/facebook-developers-world-hack-barcelona