Major Description
Problem:
Subsystem feature does not save digraph state after install of a subsystem causing a startup issue showing the exception added as an attachment.
Reproduce:
Install karaf 4.0.1
Install the subsystem feature
Install the attached application.esa file
Kill the osgi process (in an ungraceful way like kill -9)
Startup karaf
The above is a problem in the way features.core has encapsulated the region bundle and changed the persistence (it is now saved in the file 'digraph.json' which cannot be triggered by the class 'StandardRegionDigraphPersistence'). When the region implementation was an external bundle for karaf, it was possible to gain access to the persistence logic by the use of and access to the class 'StandardRegionDigraphPersistence' and save the file yourself if you changed it. This is not possible anymore in karaf version 4.0.1. We would like to be able to do so.
The feature.core functionality itself does save the state of the digraph on install of a new feature but in a different file 'digraph.json'.
The subsystems feature and other features/bundles might want to persist the digraph and get stability on ungraceful shutdowns in the same way as installing a feature.
I made a patch where I am exporting an interface that can trigger feature.core region persistence logic. It is a workaround for our code that also uses the region functionality. So it is not that I'm advising to do it like this.
Probably short term the patch could help, or a different solution like change the persistence by making an own version of 'RegionDigraphPersistence'. This class is exposed so others can use it (still there is trouble with the name of the file and access to the bundle where the file is stored).
Long term, maybe move aries subsystem implementation to the core framework and re-implement features support to use aries subsystems.
But also aries subsystems has trouble saving the digraph correctly, it is depending on a higher level logic to take that responsibility.