Plugin dependency graph

[janhoy]

Spinoff from pf4j/pf4j#51

There is currently no provision for building a dependency graph before starting an install/download with pf4j-update.

If a dependency stated in plugins.json is neither installed (PluginManager) or available in any of the UpdateRepositories, then the install process should simply fail before starting to download the requested plugin.

Perhaps the framework could provide an API to resolve dependencies from PluginInfo into a graph by consulting both PluginManager and UpdateManager. If a remote plugin depends on some plugin which is not downloaded, the API could look for the dependency id in all repositories, and if it is found, look for further dependencies etc until graph is complete. The API would make it easy for UIs to check whether a given plugin is installable or updateable before actually starting the install.

[decebals]

Make sense. Maybe class DirectedGraph from PF4J helps.

[decebals]

I can take a look at this, in my spare time.

[decebals]

We can use DependencyResolver that was improved by pf4j/pf4j#150. Just create a list with plugins descriptors and call method resolve. The result (Result) contains a lot of information related to dependencies (cyclic dependencies, not found dependencies, dependencies with wrong versions).

[PatrickHaas]

Anything new? I just got the exact problem trying to resolve a graph dependant plugins by looking at a PluginInfo

[decebals]

Anything new? I just got the exact problem trying to resolve a graph dependant plugins by looking at a PluginInfo

We can try a PR based on #22 (comment). Unfortunate for me it's not a top priority. Maybe someone can start the PR to have a base for concrete comments.