Hi @Ns334 ,
Yes, you can write an AEM service without an interface, but whether you should depends on the use case.
You can define an OSGi service as a concrete class without an interface. AEM's OSGi framework allows services to be registered and consumed directly as concrete implementations.
Use Cases for Writing an AEM Service Without an Interface
1. Simple, Internal Utility Services
If the service is only used within a single component or module and doesn’t require multiple implementations, skipping the interface can reduce unnecessary abstraction.
2. No Need for Multiple Implementations
If there's no need to switch between different implementations dynamically, using a concrete class directly simplifies code maintenance.
3. Avoiding Boilerplate Code for Small Services
For very small services (e.g., a helper service with a few methods), defining an interface may not add much value.
4. Private or Final Services
If the service is meant to be used only within a specific bundle and won’t be extended or overridden, an interface might be unnecessary.
When to Use an Interface?
- If you expect multiple implementations (e.g., different caching strategies).
- If the service is meant to be exposed as a public API for use across multiple modules.
- If you want to enable easy testing via dependency injection with mock implementations.
Example Without Interface
@Component(service = MyService.class)
public class MyService {
public String getMessage() {
return "Hello from MyService!";
}
}
Injected into another class like this:
@Reference
private MyService myService;
Regards,
Amit Vishwakarma
