Hi all, I've implemented a new interesting feature in maven-repo-helper 1.9 and maven-debian-helper 2.1, it's now possible to relocate an artifact toward another one. This is roughly the equivalent of symlinks but for the Maven dependencies.
For example, if the library FooBar 1.0 had the Maven coordinates foo:bar, and the version 2.0 changed the coordinates to org.foo:bar, it's possible to instruct Maven to redirect the dependencies on foo:bar to org.foo:bar (if the two versions are compatible of course). This feature has been supported by Maven for a long time and can now be used in maven-repo-helper and maven-debian-helper by adding the --relocate option in the debian/*.poms files. The syntax looks like this: pom.xml --relocate=groupId:artifactId[:version] Multiple relocations can be specified by appending more coordinates separated by a comma. The version is optional and defaults to 'debian'. This mechanism can conveniently replace the maven.publishedRules files. For example with Guava we can now do this: guava/pom.xml --has-package-version --java-lib --relocate=com.google.code.google-collections:google-collect,com.google.collections:google-collections This redirects the old com.google.code.google-collections:google-collect and com.google.collections:google-collections dependencies to the new one com.google.guava:guava, and the packages depending on libguava-java no longer have to declare any rule in debian/maven.rules. Old and new dependencies are resolved out of the box with no substitution rule. Another use case is the modification of the debian version of an artifact. For example the testng package currently installs its artifact with the 6.x version. This isn't optimal because the packages depending on testng have to declare a Maven rule (org.testng testng * s/.*/6.x/ * *). Now we can modify the testng package to install its artifact with the 'debian' version and relocate the old 6.x artifact to the new one. The pom options for testng would look like this: pom.xml --has-package-version --java-lib --relocate=testng:testng:6.x With this we can change the debian version without breaking the reverse dependencies. Relocations are also useful for specification jars implementing a standard API but deploying the artifact with custom coordinates. This happens typically with the geronimo-*-spec packages. For example the geronimo-jcache-1.0-spec package installs the org.apache.geronimo.specs:geronimo-jcache_1.0_spec artifact which is equivalent to javax.cache:cache-api. We can redirect the javax.cache:cache-api dependency to the geronimo implementation with: pom.xml --java-lib --relocate=javax.cache:cache-api The relocation is performed by installing an extra pom file in the repository [1]. The overhead is ~450 bytes per relocation. I started using this feature in javassist/3.20 and it works well, here the Maven 1 style coordinates (javassist:javassist) changed to the Maven 2 style (org.javassist:javassist). This relocation mechanism will probably be handy when dealing with transitions. I haven't tested but I think that libfoo2-java could declare "Provides: libfoo1-java" and install the relocation poms to avoid updating all the reverse dependencies. Enjoy :) Emmanuel Bourg [1] https://maven.apache.org/guides/mini/guide-relocation.html
