About Question enthuware.ocpjp.ii.v11.2.3449 :

[sir_Anduin@yahoo.de]

I have a question regardning the META-INF/services file

does a service module have to declare it?

And how to I enforce that a service is present on the module? I mean that (my Main module==Service consumer) can access at least one Implementation of the service?

[admin]

1. META-INF/services file is not required when you deploy a service as a module. In this case, only the provides clause in module-info is required.
META-INF/services is used for a regular , non-modular application, in which a service is loaded from classpath. (Ref. https://docs.oracle.com/en/java/javase/ ... oader.html )

2. There is no way to ensure that. Indeed, the whole point is that the service implementation should not be required for successful compilation of a service user. At run time, if the module system doesn't find any service implementation for a particular service, the application will not run.