R: NoClassDefFoundError: com/opensymphony/workflow/loader/AbstractWorkflowFactory

It was a good suggestion. Thanks, but it was not the case. For those who's interested, here is how my trip in the class-loader hell was finally over:

Last week I wrote a custom WorkflowFactory that extends AbstractWorkflowFactory, that is:

public class MactWorkflowFactory extends AbstractWorkflowFactory
{
    public WorkflowDescriptor getWorkflow(String name) throws FactoryException
    {
[...]

I put this class in a jar. This jar stays together with osworkflow, propertyset and oscore jars in web-inf/lib or in the Class-Path attribute of the "war" manifest.mf file.

osworkflow.xml declared the factory:

    <factory class="it.formula.mact.process.MactWorkflowFactory" />
  

The very first time the application used a workflow instance, osworkflow loaded the configuration, found for the factory class name and tried to load an instance of the WorkflowFactory.
This is exactly what you can see in the stack trace below, and the process failed with that error.

The only way I found to make it works was putting a reference to osworkflow jars in the manifest.mf file of my application jar. That is:

mact3-process.jar (here is where my custom workflow factory resides)
- manifest.mf -> Class-Path: osworkflow-2.5.0.jar propertyset-1.1.0.jar oscore-2.2.0.jar

I noticed that I don't need this for testing my workflow factory with junit, that is outside the application server. A normal class-path with all the needed jars is enough to run the test without problems.
I cannot say if it's an application specific issue or a class-loading specification in servlet API. My app-server is Macromedia JRun4 and usually it honors the specification very strictly.

Two final notes:

1. ConfigLoader in osworkflow loads the workflow factory class with Class.forName(). Since the class is made of "static" methods I think this is bad idea because this way ConfigLoader look for the workflow factory with the class-loader who loaded the ConfigLoader itself. Instead it should use Thread.currentThread().getContextClassLoader().loadClass(). (However this didn't solved my NoClassDefFound problem)

2. The configuration design forces to have the osworkflow jars loaded by the last class-loader in the application server class-loader hierarchy. In fact osworkflow holds the config stuff in static variables. What about reworking this in order to have an WorkflowInstanceFactory that loads and holds the configuration in instance variables? The WorkflowInstanceFactory could produce instances of Workflow objects and should be held by the application or placed somewhere, maybe in a JNDI tree where the app could retrieve it.
In this "service oriented" way osworkflow jars could be loaded by some ancient class-loader and each application could define its WorkflowFactory, Store configuration and so on. (This would get a simple solution to my NoClassDefFound problem).


cheers
stefano

-----Messaggio originale-----
Da: Pat Lightbody [mailto:[email protected]]
Inviato: venerdì 27 giugno 2003 0.40
A: [email protected]
Oggetto: Re: [Opensymphony-developers] NoClassDefFoundError:
com/opensymphony/workflow/loader/AbstractWorkflowFactory


Could it be posssible you have an older osworkflow jar laying around
somewhere?

-Pat

----- Original Message -----
From: "Travelli Stefano" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Thursday, June 26, 2003 3:19 AM
Subject: [Opensymphony-developers] NoClassDefFoundError:
com/opensymphony/workflow/loader/AbstractWorkflowFactory


> I wrote a custom WorkflowFactory and make it works in a test environment.
>
> Using the same config inside a web application it throws a strange
NoClassDefFoundError
>
> java.lang.NoClassDefFoundError:
com/opensymphony/workflow/loader/AbstractWorkflowFactory
>         at java.lang.ClassLoader.defineClass0(Native Method)
>         at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
>         at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
>         at
jrunx.util.JRunURLClassLoader.defineClass(JRunURLClassLoader.java:187)
>         at
jrunx.util.JRunURLClassLoader.findClass(JRunURLClassLoader.java:152)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
>         at
jrunx.util.JRunURLClassLoader.loadClass(JRunURLClassLoader.java:77)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:292)
>         at
jrunx.util.JRunURLClassLoader.loadClass(JRunURLClassLoader.java:77)
>         at
jrunx.util.JRunURLClassLoader.loadClass(JRunURLClassLoader.java:69)
>         at
com.opensymphony.workflow.config.ConfigLoader.load(ConfigLoader.java:95)
>         at
com.opensymphony.workflow.AbstractWorkflow.loadConfig(AbstractWorkflow.java:
523)
>         at
com.opensymphony.workflow.AbstractWorkflow.<init>(AbstractWorkflow.java:81)
>         at
com.opensymphony.workflow.basic.BasicWorkflow.<init>(BasicWorkflow.java:32)
>         at jrun__home22ejspa._jspService(jrun__home22ejspa.java:1314)
>         at jrun.jsp.runtime.HttpJSPServlet.service(HttpJSPServlet.java:43)
>         at jrun.jsp.JSPServlet.service(JSPServlet.java:110)
>         at jrun.servlet.ServletInvoker.invoke(ServletInvoker.java:91)
>         at
jrun.servlet.JRunInvokerChain.invokeNext(JRunInvokerChain.java:42)
>         at
jrun.servlet.JRunRequestDispatcher.invokeNext(JRunRequestDispatcher.java:408
)
>         at
jrun.servlet.JRunRequestDispatcher.include(JRunRequestDispatcher.java:340)
>         at
it.formula.momongaj.servlet.ViewManager.perform(ViewManager.java:112)
>         at
it.formula.momongaj.servlet.ViewManager.doGet(ViewManager.java:37)
>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
>
> ...
> ...
>
> Don't stay hours  (as I did) looking for class-path issues. It's not
ClassNotFoundException but NoClassDefFoundError and I'm quite sure that
class-path is correct.
>
> Any ideas?
>
> stefano
>
>
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