No, Dmitriy. The policy should be to use the right technique for each job, and to be respectful with the concepts in the underlying standards.
Fragments and Bundles must be used where they belong and according to their roles in the OSGi specification. Users don't need to know the rationale. They just provision the modules onto their containers and that's all. Fragments are used in very special and sporadic cases, never as a rule. Typically to alter some aspect of the host bundle, or to contribute internal resources. That's valid for some modules, but not for others. There is no point injecting Kafka, MQTT, Hibernate, Zookeeper, etc. into Ignite Core through fragments. You guys ought to stop thinking about classloaders in general, and start thinking about building the right modularity with the appropriate import and export packages. Classloaders are an internal concept which normally doesn't need to permeate to the bundle developer. On 11 Nov 2015 21:32, "Dmitriy Setrakyan" <dsetrak...@apache.org> wrote: > Raul, > > Personally, I find this policy to be a bit too scientific and it is likely > to confuse most of our users. From a consistency standpoint why not pick > one path, Bundle or Fragment, and roll with it. > > According to OSGI Wiki [1], a Fragment is something that belongs to a > parent bundle and shares the same class-loader as the parent bundle. In our > case, this is true for all the Ignite dependencies. Wouldn’t it be more > appropriate to treat all Ignite dependencies as “Fragments”. > > [1] http://wiki.osgi.org/wiki/Fragment > > On Wed, Nov 11, 2015 at 3:41 AM, Raul Kripalani <ra...@apache.org> wrote: > > > Hey Dmitriy, > > > > On Wed, Nov 11, 2015 at 1:52 AM, Dmitriy Setrakyan < > dsetrak...@apache.org> > > wrote: > > > > > Can you please describe again the philosophy between choosing a > fragment > > or > > > a bundle for Ignite dependencies. I couldn’t fully grasp it from your > > > explanation. > > > > > > > Yes, sorry, I was somewhat brief (it was late here ;-)). The policy I've > > followed is to create bundles as a first preference. I've resorted to > > fragments in the following circumstances: > > * Split package situation, e.g. package > > org.apache.ignite.internal.processors.query.h2.opt, exported by several > > modules with different contents. > > * Dynamic discovery, e.g. the one that takes place in > > IgniteH2Indexing#createH2SpatialIndex. Since we cannot resolve this > > situation using a package import (because there would be multiple bundles > > exporting that package), therefore by using a fragment we are injecting > > these classes into the class-space in the host bundle. > > * Modules offering the components listed in IgniteComponentType, which > are > > discovered dynamically. > > > > Modules that are represented as fragments are: geospatial, indexing, jta, > > spring, ssh. > > > > *Raúl Kripalani* > > PMC & Committer @ Apache Ignite, Apache Camel | Integration, Big Data and > > Messaging Engineer > > http://about.me/raulkripalani | http://www.linkedin.com/in/raulkripalani > > http://blog.raulkr.net | twitter: @raulvk > > >
