Architecture to allow third party apps

I am trying to develop an web application on Ruby on Rails. I would like to allow third party developers to develop app for my application(similar to Facebook app). Could you 开发者_运维百科guys please suggest an architecture?

This is not a vague question. He want to make their users capable to create they own apps like the Facebook. I have the same issue for one Rails 3 App and, the only reference I've found at this moment are:

Can users sign up for my app via facebook on a third-party site using my api

integration_api - SSO plugin between Rails and other web apps such as Beast, Wordpress, or PunBB.

The first link explains the minimum idea, and the second one are a Rails 2 plugin that can help to allow third party apps. However, its need to upgraded to a recent version (or in my case to Rails 3.2.13) before use integration_api.

Please, let me know if you've found other ways.