> 1- I would like to add a service to the kapua platform to know if an object is in it's perimeter or not, and to receive alarms.
Just to be sure - you would like to receive geofencing alerts? I.e. define a geo fence (via polygon or circle area definition) and then calculate if given device is currently outside the fence?
> What is the best way to develop this service :
>* Create a new package inside the project an communicate directly with classes and the data base of Kapua
>* Or develop this service outside Kapua and communicate with the platform using REST API ?
I would say that option #2 is easier to use. You should have fences defined in your custom microservice and poll device service from there to get the information about current localization of your devices.
> 2- Who actually use Kapua for commercial applications (references).
Kapua has been created by donation of EuroTech's commercial project (Everyware Cloud) to Eclipse foundation. So EuroTech guys should be able to tell you more about their existing customers.