Details on Facebook’s Plans to Allow Iframe Page Tab Apps, FBML Deprecation

Yesterday, the Facebook Developers Blog announced that Page tab applications can now be built and implemented using iframes, and FBML and FBJS will be deprecated starting March 11, 2011. Iframes will allow developers to build both canvas and tab applications on the same programming model, and integrate social plugins and the Graph API into tab apps.

Facebook announced the shift from FMBL to iframes in August, slated migration for Q4 2010, then delayed it until Q1 2011. In the meantime, some developers created what were meant to be Page tab application in iframes. Since they couldn’t integrate them before, they had to use an FBML landing tab that linked away from the Page to the iframe canvas app.

Now, developers can go into the Page Tab settings of the Developer app and change the Page Tab Type from FBML to iframe. The Page’s admin will still have to go into the Edit Page admin interface and choose to add the iframe Page tab app.

Facebook has updated its signed_request parameter for securely communicating the identity of users who visit tab apps. When users browse to a tab app, the app will receive

“the signed_request  parameter with one additional parameter, page, a JSON array which contains the ‘id’ of the Facebook Page your Tab is hosted withina boolean (‘liked’) indicating whether or not a user has liked the Page, and a boolean (‘admin’) indicating whether or not the user is an ‘admin’ of the Page along with the user info array. Your application will also receive a string parameter called app_data as part of signed_request if an app_data parameter was set in the original query string in the URL your tab is loaded on.”

This string can be used to show the user customized content. Here is an example of an updated signed_request:


Developers will also be able to include an age object in the user JSON object encoded in the signed_request. This object will be a minimum and maximum age the user must be between in order to access the application. This will not give developers access to a user’s specific age.

Applications that include content specified in Facebook’s alcohol guidelines will have to use the age object to prohibit underaged users from gaining access, or risk violating Facebook’s alcohol policy. Previously, FMBL tags had to be used to exclude underage users.

The option to integrate social plugins and the Graph API opens new potential for making more social Page tab apps. Developers could include Like buttons for specific pieces of content to create broadcast channels to subsets of their users. Social game developers have had some success with implementing the Like button on their canvas app to let users share specific pieces of content with friends.

The Comments plugin will offer another way for users to leave feedback in addition to the wall and discussion board. It could also help apps grow, since comments can be posted to a user’s wall. The Facepile could be used to show friends who’ve used the tab app, or the Recommendations and Activity Feed plugins could suggest what users should do first within a tab.

FMBL Deprecations and the Developer Roadmap

Starting March 11th, 2011, developers won’t be able to build new FMBL apps, and Pages won’t be able to add static FBML apps as Page tabs. All existing FMBL tab and apps will continue to function, and will still be able to be edited for the immediate future. However, it seems that Facebook will eventually remove FBML entirely.

XFBML tags that support social plugins will not be deprecated, and will continue to function normally.