Right now the only way to use a custom service in the app is to create a custom version of the app. Also, the check of local_mobile is a bit hacky and it's causing us some problems. We should consider being able to configure the service to use from Moodle itself.

We've thought something like:

• Check if site exists should return which service to use. If that's not feasible, then we could authenticate the user with the default service, perform a "get_site_info" call and in there get the service to use (although that can be tricky with SSO). We can also support custom entry points (local/mobile/check.php, local/myawesomeaddon/whatever.php, etc.).
• In any case, get_site_info should return the WS prefix (e.g. local_mobile_) and we'd use that value instead of hardcoding local_mobile_ in our app.