(previously posted on core-libs-dev, moved by request) I've spent some time discussing module names for logging implementations recently: https://github.com/jodastephen/jpms-module-names/wiki/Logging-APIs https://issues.apache.org/jira/browse/LOG4J2-2056 https://jira.qos.ch/browse/SLF4J-407?jql=text%20~%20%22jpms%22
Most logging projects are split in two - an API and an Implementation - where the recommended solution going forwards is to use ServiceLoader to find the implementations. A few old projects don't have this split, and have API and Implementation together (eg Commons-Logging). Everyone agrees that the module name for the API must always be the same. ie. if the SLF4J team provides a module that simulates the Commons-Logging then it must have the same module name as Commons-Logging. However, there are two choices for the implementation jars. Option 1: All modules that implement a particular logging API must have the same module name eg. every module that implements "org.slf4j" (the API) must be named "org.slf4j.impl" Option 2: The module name of the implementation can be whatever name makes sense. 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. I'm leaning towards option 2, as it is simpler and does not require all implementations to have the same module name (which would be difficult to require). Any other considerations I'm missing? Stephen
