The Griffon Trove: troubleshooting plugin upgrades

Now that Griffon 1.0.0 is available there may be some people experiencing upgrade problems. Say you have an existing Griffon application created with 0.9.5; this application has several plugins installed, some of them have a dependency on swing-0.9.5. All goes well when upgrading this application to Griffon 1.0.0 but any further commands make it fail with an error similar to the following one
Welcome to Griffon 1.0.0 - http://griffon-framework.org/ Licensed under Apache Standard License 2.0 Griffon home is set to: /usr/local/griffon Base Directory: /private/tmp/sample Running script /usr/local/griffon/scripts/Clean.groovy Resolving dependencies... Dependencies resolved in 668ms. Environment set to development Resolving framework plugin dependencies ... Framework plugin dependencies resolved in 591 ms. Resolving plugin dependencies ... Some dependencies have conflicts. -= INSTALLED =- -= MISSING =- ! miglayout-0.4 from griffon-local ! swing-0.9.5 from griffon-local ! swing-1.0.0 from griffon-local Could not resolve plugin dependencies.What's going on here? The answer lies in stricter upgrade policies enforced since 0.9.5 when the plugin system was redesigned. Previous to 0.9.5 you could upgrade to a newer version in a very "careless" way, that is, just pick the latest number and do it. However this could to unexpected problems if there's a binary incompatibility lurking in the release. Because of this the team decided to enforce the following rules when resolving plugin version

• split version numbers into major.minor.revision
• if major number differs then abort
• if minor number differs, pick the bigger one
• if revision number differs, pick the bigger one
• tags should be treated in descending alphabetic order with the exception of -SNAPSHOT which is always last

With these rules we see that miglayout depends on swing 0.9.5 but the application has a dependency on swing 1.0.0. This is treated as a binary incompatible upgrade so the build stops immediately and informs you of the conflict. How do we solve the conflict then? Simply read through the release notes and plugin docs available at Griffon Artifact Portal and check for yourself that the migration path is safe. When convinced issue any griffon command, such as clean for example, with the following flag enabled
griffon -Dgriffon.artifact.force.upgrade=true cleanThis flag will the build to accept plugin upgrades even if there are differences in major numbers.

By the way, in case you're curious about the character ! next to each plugin name/version it means there's a conflict in that plugin or any of its dependencies. Additional characters may be present (one per line)

• . the plugin is installed
• + the plugin will be installed
• - the plugin will be removed
• ? the plugin could not be resolved

For example, adding a plugin dependency on bogus-0.0.0 results in the following output
-= INSTALLED =- . miglayout-0.4 . swing-1.0.0 . swing-1.0.0 -= MISSING =- ? bogus-0.0.0 not found in any repository

Keep on Groovying!