When to use an aidl based service?

Question

Under what circumstances would using AIDL to define a service interface be the correct decision (rather than just creating an extension to the service class)?

Answer 1

Merely extending a service class will not allow your service to expose its methods to outside entities. If you want your service to be exposed/used by code which runs out of your android app, you will have to define an AIDL for it. This AIDL will be shared and be formed as contract for your service. Refer this http://developer.android.com/guide/components/aidl.html.