[rules-users] drools 6 and osgi

Cristiano Gavião cvgaviao at gmail.com
Fri Jun 21 21:35:21 EDT 2013 

Florian,
The best approach that I could figure out is to use the ServiceLoader.

It is not a good approach from a OSGi point of view.... but it will work 
on both words...

check:

- http://docs.oracle.com/javase/6/docs/api/java/util/ServiceLoader.html
- the OSGi Enterprise Spec 5, RFC 133 - Service Loader Mediator 
Specification and its RI implementation here: 
http://aries.apache.org/modules/spi-fly.html


regards


On 21/06/13 19:21, Florian.Pirchner wrote:
> hi cristiano,
>
> yep. class#forname is just one issue.
> i agree that the modularity issue is an important one too.
>
> to provide a framework for non osgi and osgi environments is really a 
> challenge. my prefered way would be the use of osgi services to avoid 
> the classloading issues. so the problems with dependencies would not 
> influence the system. only api is required as import package. the impl 
> is invisible for the consumer.
> but for now i have no idea how a proper implementation could look like.
>
> peter kriens suggested the use of http://code.google.com/p/pojosr/ to 
> build an osgi like system in non osgi environments.
> but never used it. and i also do not know whether it might help with 
> osgi integration. does anybody have experience with pojosr?
>
> @mark: what are your current ideas about integrating osgi properly?
>
> best florian
>
> Am 21.06.2013 um 23:49 schrieb Cristiano Gavião <cvgaviao at gmail.com 
> <mailto:cvgaviao at gmail.com>>:
>
>> Florian,
>>
>> Don't think that the problem that we are facing in Drools6 is because 
>> the Class.forName on its own.
>>
>> But the problem is from which bundle it is being called and where 
>> resides the class that it is trying to load...
>>
>> Definitively one bundle CAN'T load classes that resides in another 
>> bundle, unless you specify a import of the package... That is why 
>> currently kie-api has an import to org.drools.compiler.kie.builder.impl
>>
>> so the solution must be composed by two steps: Repackage some 
>> classes, so a class will be loaded by its own bundle and use services...
>>
>> On 21/06/13 03:30, Florian Pirchner wrote:
>>> Hi Mark,
>>>
>>> i did some research. Indeed a very complex issue.
>>> Tried to find out the difference about Class.forName(String) and 
>>> Class.forName(String, boolean, ClassLoader). Both of them are 
>>> delegating to native jvm methods and the difference seems to be in 
>>> resolving the class and the way that caches work.
>>>
>>> In http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6500212 they 
>>> are pointing to use Class.forName(String, boolean, ClassLoader). 
>>> Could find that method call in some drools and jbpm classes. For 
>>> instance compiler...
>>>
>>> But there are also a lot of Class.forName(String) calls too. 
>>> Specialy in parts of code where no array-types come into play.
>>> For instance JavaHandlerWorkItemHandler calls (Class<JavaHandler>) 
>>> Class.forName(className).
>>>
>>> Maybe it would be a good idea to replace Class.forName() for issues 
>>> that exclude array-types by classloader.loadClass().
>>>
>>> WDYT?
>>>
>>> Best Florian
>>>
>>>
>>>
>>> Am 20.06.13 17:28, schrieb Mark Proctor:
>>>> There are bugs with loadClass and serialisation :(
>>>> http://lists.jboss.org/pipermail/rules-dev/2011-November/003681.html
>>>>
>>>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6500212
>>>> "Thus, we highly recommend replacement of this code:
>>>>    myClassLoader.loadClass(className);
>>>>
>>>> With this code:
>>>>
>>>>    Class.forName(className,false,myClassLoader);"
>>>>
>>>> Mark
>>>> On 20 Jun 2013, at 15:01, Florian Pirchner 
>>>> <florian.pirchner at gmail.com <mailto:florian.pirchner at gmail.com>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> i also saw all the Class.forName. Class.forName additionally uses 
>>>>> a very
>>>>> aggressive class caching policy.
>>>>> See here:
>>>>> http://blog.osgi.org/2011/05/what-you-should-know-about-class.html
>>>>> http://blog.bjhargrave.com/2007/09/classforname-caches-defined-class-in.html
>>>>>
>>>>> I do not understand why API imports compiler.impl? Maybe to enable
>>>>> class#forname i guess.
>>>>>
>>>>>
>>>>> Is there an intention to use a more modularized way in v6 beta4 when
>>>>> OSGi support will be implemented?
>>>>>
>>>>> Thanks Florian
>>>>>
>>>>>
>>>>> Am 20.06.13 15:43, schrieb Cristiano Gavião:
>>>>>> Hi,
>>>>>>
>>>>>> Well, besides the fact that the services that we used on version 
>>>>>> 5.x is
>>>>>> still there, I'm not that optimist with Drools 6 running well in 
>>>>>> an OSGi
>>>>>> container... at least not currently...
>>>>>>
>>>>>> Last week I played a bit too with Jbosgi and Wildfly and got a lot of
>>>>>> classloading errors due some factory classes trying to load 
>>>>>> classes that
>>>>>> are in another bundles...
>>>>>>
>>>>>> what surprise me most was that kie-api has an import to
>>>>>> org.drools.compiler.kie.builder.impl ! :)
>>>>>>
>>>>>> regards,
>>>>>>
>>>>>> John
>>>>>> On 17/06/13 19:39, Florian.Pirchner wrote:
>>>>>>> hi,
>>>>>>>
>>>>>>> i got a question about osgi support.
>>>>>>> is beta 3 already useable in osgi environments? could see that 
>>>>>>> activators are registering v5 api as services.
>>>>>>>
>>>>>>> is it possible to consume osgi services in the script tasks and 
>>>>>>> rules by context? is this planned for version 6? would be a 
>>>>>>> great feature.
>>>>>>>
>>>>>>> thanks a lot for answer
>>>>>>> florian
>>>>>>> _______________________________________________
>>>>>>> rules-users mailing list
>>>>>>> rules-users at lists.jboss.org
>>>>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>>> _______________________________________________
>>>>>> rules-users mailing list
>>>>>> rules-users at lists.jboss.org
>>>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> rules-users mailing list
>>>>> rules-users at lists.jboss.org
>>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> rules-users mailing list
>>>> rules-users at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>
>>>
>>> -- 
>>> Mit besten Grüßen
>>> Florian Pirchner
>>> Fohlenweg 22
>>> 2301 Probstdorf
>>> Tel: +43 650 7772338
>>> florian.pirchner at gmail.com
>>>
>>>
>>> _______________________________________________
>>> rules-users mailing list
>>> rules-users at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org <mailto:rules-users at lists.jboss.org>
>> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20130621/94da91c7/attachment-0001.html

More information about the rules-users mailing list