Ushahidi V2 has an extensible API; that means you can add new components to it (e.g. add new models to the API etc). 

To do this, you need to:

1. Add your new API component to the API configuration file, application/config/api.php, so the API knows which files to call when it sees your new type in the API call.  For example, this lines were added to include Messages in the API:
   •  "messages" => "Admin_Messages",
     
2. Add a file for your new API component to directory application/libraries/api, e.g. this file was added for Messages API: 
   • application/libraries/api/MY_Messages_Api_Object.php
   • then add code specific to your new API type
3. Optional: if you want admin-only for all or part of your API to be admin-access-only, then add a file for that too. e.g. this file was added for Admin Messages API: 
   • application/libraries/api/MY_Admin_Messages_Api_Object.php
   • and add code specific to your new API type
4. Add any new functions needed by the API to your model files, e.g. for Messages API, this file was edited: 
   • application/models/message.php
     

That's it.