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Additional considerations on the new Features service

I want to give a bit more detailed explanations on some new stuff provided by the Karaf 4.x FeaturesService.
Transitive closure The karaf-maven-plugin provides a new goal named verify.  It's an enhanced version of the previous validate goal.  This goal helps ensuring that all features are transitively closed with respect to their requirements.  This means that all the requirements for a given feature can be fulfilled without relying on already installed bundles or features.  This new goal actually uses the OSGi resolver to ensure that, so that it ensures your features can be deployed everywhere, without additional requirements. Viable deployments One of the new features I mentioned in my previous post is that the new Features service ensures that the features requirements are fully available.  When installing new features, this is usually not much of a problem, as we usually only add new bundles.  However, when uninstalling a feature, things can be a bit more complicated when thos…

Karaf 4.0 is about to be released !

Almost 3 years since I haven't blogged, so I'm using the fact that the Karaf 4.0 release in under vote to start again.

Karaf 4.0 brings a lot of new features, but one of the most important one is the new features service.  It is originally a port of the Fuse/Fabric agent resolver to Karaf 4, but has since been extended a lot (and has actually been integrated back into Fuse 6.2).

This new features services is used to install well known features, but even if it reuses the same features xml definition, it's not limited to those anymore and works in a very different way.  The main difference is that the original features service (in Karaf 2.x and 3.x) is quite blind when it comes to installing features.  When a user asks for a feature installation, the process was quite simplistic: the service mainly goes through the list of bundles listed in the feature and install them.  The introduction of the resolver flag brought some intelligence to the process, as the old and deprecate…