Module naming for logging implementations

[Stephen Colebourne]

Thanks Alex and David, those are good arguments. So option 2 it is.
Stephen

On 26 October 2017 at 23:05, David Lloyd <david.lloyd at redhat.com> wrote:
> On Thu, Oct 26, 2017 at 3:03 PM, Stephen Colebourne
> <scolebourne at joda.org> wrote:
>> For most service providers, option 2 is obvious, however for logging
>> it is generally the case that only one implementation should be
>> present. If all the jar files that implement a specific logging API
>> had the same module name (option 1) then the module system could
>> ensure that only one was loaded. This is a particular concern as it is
>> not uncommon for a jar file in Maven Central to depend on a specific
>> implementation of logging when it should only be depending on the API.
>
> This is actually a general special case (if you follow my meaning):
> that of an API which uses services to locate an implementation, yet
> typically only one implementation should be existent and used.  For
> example, I/O or other platform-dependent systems also spring to mind:
> they have a common API, but you generally only want one implementation
> (except maybe in some special cases - just like for logging).
>
> I think that in any case, be it a singleton-ish provider case like one
> of the above or a multiple-provider case, it is always appropriate to
> choose a unique module name for implementations. It's not appropriate
> for an API to prescribe an implementation module name.
>
> Perhaps we can enhance Jigsaw in the future with some kind of feature
> that enforces singleton implementations, if it becomes any sort of
> practical problem.
>
> --
> - DML