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We had some downtime in between projects several weeks back and decided to get social with social networking. Since most of the studio is on Facebook, we decided to develop a Facebook application. It’s a simple whack-a-mole type game with a table of your friend’s high scores.

WHAT WE LEARNED:

1. Facebook, besides being the number two social networking site, is also the creator of a small army of Facebook branded programming languages. HTML? They’ve got that, but it’s called FBML. SQL? They’ve got that too, FQL. JavaScript? FBJS. And so on.
2. Facebook documentation, while complete, is really quirky. It’ll list all the parameters of a function, but doesn’t list what order it should go in. Nor do they provide a sample call. (http://developers.facebook.com/documentation.php?v=1.0&method=friends.areFriends).
3. A “multi-friend selector” has a built in skip button that cannot be optioned out, so when placed in certain context really confuses the user. It’s a known issue, and Facebook “won’t fix”.
4. The “profile page” is the page most users see, it’s the one where it has the user’s feeds, list of the user’s friends, and the applications the user’s installed. The “canvas page” is the application’s page. There’s also a “Page page”, which is page specific for groups or companies (http://www.facebook.com/pages/Plexipixel-Inc/22585493640).
5. A Facebook “session key” is a unique key based on the currently logged in user. An “infinite session key” is like a regular session key, except it doesn’t expire. A session key is essentially what logs you in or keeps you logged in on Facebook.
6. Facebook caches everything. The first time you run your application on the canvas page, Facebook, like a good hamster, pulls everything from your server that’s used: images, SWF’s, Virgin Mary statues, even output from PHP files. We think they do this for performance reasons. Instead of having the data for the page come from various uncontrolled servers, it’ll come from either one of their servers or several servers under their control, so pages will load in a consistent manner, unlike MySpace.

SOME PROBLEMS WE FACED

1. Because of this hamster-like need to cache things, it leads to problems when the data you want is dynamic, such as a table of high scores. They provide a command to force a refresh of the cache ($facebook->api_client->fbml_refreshRefUrl('yourUrlHere’);), which works great on the canvas page, but, unfortunately does not get called when it’s placed on the profile page, for probably the same reason as above.
   • Take the refresh cache command and the set profile FBML command and put them on a PHP page.
   • Get an infinite session key.
   • Then use some kind of scheduler, like a CRON job, along with your infinite session key (so, you can access Facebook without logging in), then call it at some interval.

Our Fix:

There are several ways of getting around this, and they’re all variations on a basic theme:

So, when we ran our update script the first time, it worked, until we went to a test account and found out that we’ve updated our test user’s score table with the scores of our friends, not the test user’s friends. And the reason for that is the Facebook function that returns a list of your friends is not based off your user ID, but rather based off of your session key. When we ran the update script instead of placing a table of the user’s friend’s scores, we placed a table of MY friend’s scores, ON EVERYBODY’S PROFILE PAGE.

2. There is no default “Add to Profile” option on the Invite Friend Notification, so if you didn’t know about it, you’ll be sending an “invite friend” request with only an “Ignore” option. This is by far the most frustrating thing, because, one, it makes you look really stupid. And two, Facebook, what could you possibly think a user wants to do when they click on “Invite a Friend to [app name]”? Send them a cookie?

Our Fix:

Make sure to add the “Add to Profile” option!

Overall, we learned a lot from our first look into the world of coding Facebook apps. Keep an eye out for more tips and tricks as we continue to explore the possibilities of social networking applications!