Share jar package and activiti class loader

[rcosta1]

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 "$CATALINA_HOME/shared/lib" folder but when I use activiti-explorer I recive "Could not load class …"
  (catalina.properties is configured to read all jars into this folder: "shared.loader=${catalina.base}/shared/lib/*.jar" )
  It's strange that "$CATALINA_HOME/shared/lib/ojdbc14.jar" work well
 
- to put my jar file inside tomcat "$CATALINA_HOME/lib/" but it's the same (in activiti-explorer I recive "Could not load class …")

Alternative I have to put my jar inside all webapp but I would like to know how can I share my jar.

Best regards
Riccardo Costa

[frederikherema1]

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"?

[npasquetto]

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

[frederikherema1]

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

[npasquetto]

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.

[frederikherema1]

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…

[npasquetto]

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.

[frederikherema1]

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.

[npasquetto]

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!

[npasquetto]

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