Basically annotations like @Service, @Repository, @Component, etc. they all serve the same purpose:

auto-detection when using annotation-based configuration and classpath scanning.

From my experience I am always using @Service annotation on the interfaces or abstract classes and annotations like @Component and @Repository for their implementation. @Component annotation I am using on those classes which serves basic purposes, simple Spring beans, nothing more. @Repository annotation I am using in the DAO layer, for e.g. if I have to communicate to the database, have some transactions, etc.

So I would suggest to annotation your interface with the @Service and other layers depending on the functionality.

Basically annotations like @Service, @Repository, @Component, etc. they all serve the same purpose:

auto-detection when using annotation-based configuration and classpath scanning.

From my experience I am always using @Service annotation on the interfaces or abstract classes and annotations like @Component and @Repository for their implementation. @Component annotation I am using on those classes which serves basic purposes, simple Spring beans, nothing more. @Repository annotation I am using in the DAO layer, for e.g. if I have to communicate to the database, have some transactions, etc.

So I would suggest to annotate your interface with the @Service and other layers depending on the functionality.