topic Re: Share jar package and activiti class loader in Alfresco Archive

Share jar package and activiti class loader

rcosta1 — Fri, 05 Oct 2012 13:47:15 GMT

Hi,I would like to share a package that I write cross all my webapp inside a tomcat 6.0.5 installation of activiti 5.9.I have read that "$CATALINA_HOME/shared/lib seems to be gone in 6.0 (it was there in 5.5)".I have try various scenarios:- to put my jar file inside tomcat "$CATALINA_HOME/shared/lib

Re: Share jar package and activiti class loader

frederikherema1 — Tue, 09 Oct 2012 08:13:49 GMT

Adding the "shared/lib/*jar" in catalina.props should expose the all jar's in the shared class loader for all web apps. Activiti uses the following mechanism to lookup classes:

Try custom classloader, if set in configuration

If previous fails, use Thread.currentThread().getContextClassLoader()

If previous fails, use ReflectUtil.class.getClassLoarder() (default class loader where activiti jar is loaded in)

Strange that even in the main "/lib" folder, this doesn't work. What is the "cause" exception of the "could not load class"?

Re: Share jar package and activiti class loader

npasquetto — Wed, 24 Oct 2012 12:17:44 GMT

Hi Frederik, I've got exactly the same behavior than Riccardo.

What is the "cause" exception of the "could not load class"?

The exceptions are:
org.activiti.engine.ActivitiException: couldn't instantiate class
Caused by: org.activiti.engine.ActivitiClassLoadingException: Could not load class:Caused by: java.lang.NoClassDefFoundError: org/activiti/engine/delegate/JavaDelegateIt seems that problem isn't on the visibility of my implementation but on the visibility of the activiti engine libraries. Could be?

Best Regards

Re: Share jar package and activiti class loader

frederikherema1 — Wed, 24 Oct 2012 14:09:12 GMT

Yes, it seems to be the case… Altrough it's strange that activiti-classes itself can't find activiti-classes in the class loader :s

Re: Share jar package and activiti class loader

npasquetto — Wed, 24 Oct 2012 14:18:39 GMT

Yes, it seems to be the case… Altrough it's strange that activiti-classes itself can't find activiti-classes in the class loader :s

Really.

Re: Share jar package and activiti class loader

frederikherema1 — Wed, 24 Oct 2012 14:30:12 GMT

NoClassDefFoundError will come if a class was present during compile time but not available in java classpath during runtime. So make sure the activiti-jars on on the runtime-path and visible to the class loader.

Beware, the SHARED class loader (libs shared with all web apps) can't access the web-app specific classes (which probably contains the activiti-jar).

Make sure the activiti-jar (engine) is available in the SHARED path IF you depend on it…

Re: Share jar package and activiti class loader

npasquetto — Wed, 24 Oct 2012 15:15:16 GMT

Thanks for the reply, Frederik!

But it's not very clear for me, when you say:

Beware, the SHARED class loader (libs shared with all web apps) can't access the web-app specific classes (which probably contains the activiti-jar).

Make sure the activiti-jar (engine) is available in the SHARED path IF you depend on it…

It's OK, but I'm in a different situation: I search for my jar from the webapp in the shared class loader, but the webapp has the activiti-jar in his class loader.

Re: Share jar package and activiti class loader

frederikherema1 — Thu, 25 Oct 2012 08:24:41 GMT

To summarize what Iw as saying:
- Your jar-file (containing the JavaDelegate implementation) is present in the SHARED class path.
- The activiti-engine.jar file is in the web app's class loader (WEB-INF/lib).

If this is the case, than it makes sense.. Try adding activiti-engine-5.*.jar in the shared class path as well, since YOUR jar-file depends on it.

Re: Share jar package and activiti class loader

npasquetto — Fri, 26 Oct 2012 08:43:25 GMT

Hi frederik,

Try adding activiti-engine-5.*.jar in the shared class path as well, since YOUR jar-file depends on it.

Ok, thanks for your instructions!

Re: Share jar package and activiti class loader

npasquetto — Fri, 26 Oct 2012 13:02:02 GMT

Hi Frederik,

Try adding activiti-engine-5.*.jar in the shared class path as well, since YOUR jar-file depends on it.

After adding the engine jar another exception has been thrown that required also the slf4j jar. Adding slf4j this exception has been thrown

org.activiti.engine.ActivitiException: org.mytest.MyDelegate doesn't implement org.activiti.engine.delegate.JavaDelegate nor org.activiti.engine.impl.pvm.delegate.ActivityBehavior

But the same jar (same file), used in the webapp lib folder run correctly. I don't understand why.

Re: Share jar package and activiti class loader

ronald_van_kuij — Fri, 26 Oct 2012 17:04:01 GMT

THat is often caused by classes loaded from two different classloaders.