A recent contribution to the felix maven-bundle-plugin is that baseline goal which checks and/or reports semantic versioning changes. It basically does a binary diff with the latest release of the same artifact for changes and verify that the changes are compatible with the semantic versioning rules.
I think we should try to leverage those, but without changing our release lifecycle. This could be done the following way: * keep our artifacts versioning and release mechanism untouched * add the baseline plugin * in 4.0, exported packages would all have a version of 4.0.0 * follow semantic versioning for all releases > 4.0 This would mean that karaf 4.1 would have packages in version 4.0, 4.0.1 or 4.1. Note that the version used for karaf (and for bundles) isn't tied in any way to the version of the packages. But this would also help making sure we stay compatible, and whenever we do a new release (be it 4.1 or 5.0), help users with migration because the package versions would not be changed unless needed. Downsides: * users may be impacted in the future with the fact that not all packages have the same version, but this should usually be minor, as tools usually grab the version of the packages from the binary when writing an import package. However, for those which do not leverage those features, this will have an impact * bug fix releases may be more tricky : the main problem is that with semantic versioning, once a package is released with a minor upgrade, there's no room left The last point needs an explanation. Let's say we have a package in version 4.0.0 in karaf 4. We later release karaf 4.1 with a very minor addition to that package, so that this package is now in version 4.0.1. If we later find a bug which require a fix, we won't be able to release a karaf 4.0.1 with a micro change in that package, so we'd have to at least backport the interface change from 4.1 in 4.0.1 (even if we don't backport the implementation) and then do the fix with a 4.0.2 package version. Not sure this is very clear, but the last point has always been my worry about semantic versioning. Thoughts ? Guillaume
