RE: Karaf 4.2.0M2 issue with classpath

[Siano, Stephan]

Hi,

I think the root cause of the issue is something a little more fundamental with 
Karaf 4.2.0:

Java 9 removed the endorsed mechanism that could override classes from the JDK. 
Karaf versions before 4.2.0 used that mechanism to replace some javax APIs 
(like the Stax API javax.xml.stream) with a servicemix wrapped implementation 
which was changing the implementation lookup in a way that was working with 
OSGi.

Without that endorsed stuff, you will fall back to the JDK implementation of 
XMLInputFactory which finds the services definition from Woodstox (which says 
that com.ctc.wstx.stax.WstxInputFactory is the XMLInputFactory implementation 
to use) and then tries to load that class with its own class loader (the root 
class loader) or the ThreadContextClassLoader.

Now you have different options (which all have their disadvantages):

  1.  As you already found out you can import the Woodstox packages from all 
bundles using Stax and set the Thread Context Class loader to the class loader 
of that bundle. The disadvantage of that approach is that the bundle using Stax 
has to know about the implementation (which is not supposed to be the case).
  2.  Put woodstox into the system classloader (into ext or endorsed) and 
export the packages from the system bundle. The disadvantage of this approach 
is that this will only work with Java 8 (not with Java 9 and later). 
Alternatively you could put the servicemix wrapped Stax API into the endorsed 
folder (as with older Karaf versions), which will also only work with Java 8.
  3.  Import the woodstox bundle into the bundle using Stax and instantiate the 
factory implementations directly (not via the Interface). Here the using bundle 
needs to control the factory instantiaton, but you don’t need to set the thread 
context class loader.

I have not yet figured out what the real solution about that is supposed to 
look like. I have asked that question already to the karaf-dev list (because 
the question is actually how Karaf 4.2 and later is supposed to handle the SPI 
pattern), but I didn’t get an answer for it.

Best regards
Stephan

From: cschneider...@gmail.com [mailto:cschneider...@gmail.com] On Behalf Of 
user-return-18355-stephan.siano=sap@karaf.apache.org
Sent: Mittwoch, 21. März 2018 18:35
To: user@karaf.apache.org
Subject: Re: Karaf 4.2.0M2 issue with classpath

If you have control over that code then the TCCL is a good solution.

Christian

2018-03-21 16:54 GMT+01:00 bobanbp 
<boba...@gmail.com<mailto:boba...@gmail.com>>:
Hi Christian,

Thanks for your reply. I tried your suggestion but without success. The only
solution that works is to explicitly change class loader:

ClassLoader tccl = Thread.currentThread() .getContextClassLoader();
Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());
my code that uses AWS SDK
Thread.currentThread().setContextClassLoader(tccl);



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--
--
Christian Schneider
http://www.liquid-reality.de

Computer Scientist
http://www.adobe.com

Re: Karaf 4.2.0M2 issue with classpath

[Christian Schneider]

If you have control over that code then the TCCL is a good solution.

Christian

2018-03-21 16:54 GMT+01:00 bobanbp :

> Hi Christian,
>
> Thanks for your reply. I tried your suggestion but without success. The
> only
> solution that works is to explicitly change class loader:
>
> ClassLoader tccl = Thread.currentThread() .getContextClassLoader();
> Thread.currentThread().setContextClassLoader(this.
> getClass().getClassLoader());
> my code that uses AWS SDK
> Thread.currentThread().setContextClassLoader(tccl);
>
>
>
> --
> Sent from: http://karaf.922171.n3.nabble.com/Karaf-User-f930749.html
>



-- 
-- 
Christian Schneider
http://www.liquid-reality.de

Computer Scientist
http://www.adobe.com

Re: Karaf 4.2.0M2 issue with classpath

[bobanbp]

Hi Christian,

Thanks for your reply. I tried your suggestion but without success. The only
solution that works is to explicitly change class loader:

ClassLoader tccl = Thread.currentThread() .getContextClassLoader();
Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());
my code that uses AWS SDK
Thread.currentThread().setContextClassLoader(tccl);



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Karaf 4.2.0M2 issue with classpath

[bobanbp]

I'm migrating our application to the newer version of Karaf and I started
testing our application on karaf 4.2.0M2. Before 4.2.0M2 I performed some
tests on Karaf 4.1.4 and it worked fine, but on 4.2.0M2 I hit an issue. I am
getting the flowing error:

javax.xml.stream.XMLInputFactory: Provider
com.ctc.wstx.stax.WstxInputFactory not found.

It seems that AWS SDK bundle that we use uses package javax.xml.stream from
org.apache.felix.framework that imports
com.fasterxml.woodstox.woodstox-core, but for some reason 
com.ctc.wstx.stax.WstxInputFactory is not visible. I am using apache CXF
3.2.0 and it provides woodstox-core bundle.



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