A smarter bundle tool should be able to eliminate unused utility classes from such bundles, greatly reducing their size. But making bundles more fine grained is definitely a good tip too.
Greetings, Marcel On 1 Dec 2010, at 15:58 , Simon J Archer wrote: > > I have had a similar experience with utility bundles. Be sure to carefully > manage the prerequisites of a commonly used bundle. The trouble, as Jeff > correctly pointed out, is that they become dumping grounds for useful types, > and as a result their prerequisites (that is, the other bundles upon which > they depend) tend to grow. While having a large number of prerequisites is > not in itself a bad thing, it has a negative impact on all those bundles > higher on the stack that just want to use one or two types in the utility > bundle. In my case I saw a small 2 MB application balloon to over 20 MB just > because someone updated one of the packages I imported, and consequently the > bundle's prerequisites. > > So, what's the solution? Ensure that your utility bundle remains highly > cohesive and does not become a grab-bag of unrelated helpers. Far better to > create multiple finely-grained, highly cohesive (and loosely coupled!) > bundles since this will result in a far more flexible bundle dependency > graph, be it at the cost of some complexity. > > I've seen first hand the reaction people have to finely grained bundles, and > I've seen people merge bundles to make things "easier". The reality is that > when you merge bundles you are trading flexibility for simplicity (less > bundles). One day I'll write a packaging tool that merges bundles for > deployment, giving us the best of both worlds. > > To that end, I would like to suggest using Import-Package rather than > Require-Bundle, since this gives you more flexibility regarding you > prerequisites. But let's save that debate for other thread. > > Simon > > > From: Peter Kriens <peter.kri...@aqute.biz> > To: OSGi Developer Mail List <osgi-dev@mail.osgi.org> > Date: 12/01/2010 04:00 AM > Subject: Re: [osgi-dev] Utility package as a bundle? > Sent by: osgi-dev-boun...@mail.osgi.org > > > > > The problem with util bundles is that their transitive dependency has a > tendency to swell. That would be no problem if the util bundle was cohesive > but they rarely are. Example, I once debugged a case where about 20 Mb of > external dependencies were dragged in because the developers used one two > line method in Apache commons collection. > > For this reason, bnd has the Conditional-Package instruction. This > instruction is ignored while building the bundles but after the content is > set, it will match any imports against this instruction. Any matching > packages are copied to the bundle which is then reanalyzed until no more > matching imported packages are found. For example: > > Private-Package: biz.aQute.whatever.impl.* > Conditional-Package: biz.aQute.util.* > > Any imports from biz.aQute.util.* will automatically be included in your > bundle in your private are. That is, these utils will not be shared. Many > bundles can include the same package, one of the great advantages of OSGi > over other Java module systems. > > Obviously this will create redundancy but it gives you less coupling, there > is a of course a trade off. However, it is binary redundancy, the source code > is still in one location. > > > I find this Conditional-Package to be extremely effective for specially > developed util jars. The model works best when the utils themselves are in > separate packages, this allows you to pick and choose and not pay for > unwanted dependencies. > > Kind regards, > > Peter Kriens > > > > On 1 dec 2010, at 00:51, Wesley Silva wrote: > > > Hi, > > > > I'm currently migrating an existing web application to OSGI. During the > > process I saw the utility package, where there are classes to manipulate > > things like date, strings, files, cryptography and so on. Almost all web > > applications in my company have this kind of package so I was wondering if > > it was a good idea to turn it into a reused piece of software. > > So here is my question, is it a good idea to turn it into a bundle? If so, > > how would this bundle look like? Would it publish some > > service thought interfaces or just export packages? Any suggestions? > > > > -- > > Att, > > Wesley > > MSc Candidate in Software Engineering > > Specialist in Test Analisys (CIn/UFPE - Motorola) > > B.S. in Computer science - UFS > > Sun Certified Java Programmer > > Sun Certified Web Component Developer > > _______________________________________________ > > OSGi Developer Mail List > > osgi-dev@mail.osgi.org > > https://mail.osgi.org/mailman/listinfo/osgi-dev > > > _______________________________________________ > OSGi Developer Mail List > osgi-dev@mail.osgi.org > https://mail.osgi.org/mailman/listinfo/osgi-dev > > > _______________________________________________ > OSGi Developer Mail List > osgi-dev@mail.osgi.org > https://mail.osgi.org/mailman/listinfo/osgi-dev
_______________________________________________ OSGi Developer Mail List osgi-dev@mail.osgi.org https://mail.osgi.org/mailman/listinfo/osgi-dev
