ClassNotFoundException with EHCache-Atomikos

I'm trying to use EHCache's transactional abilities together with Atomikos and Apache Tomcat (for usage with JMS and Hibernate but that's just to assure the sceptics I really need JTA).

I'm currently working on a small POC where I'm trying to put an instance of MyValue which implements Serializable and when I try to commit the transaction I get the __ with ClassNotFoundException as the root (The stack trace is at the end).

When I jar the MyValue file and put it under %TOMCAT_HOME%\lib I get no exception.

It's important to add that due to an instruction I saw on the atomikos tutorial both Atomikos's jars and EHCache jars are under %TOMCAT_HOME%\lib.

This is the quote:

When the Atomikos transaction manager is installed globally in Tomcat, you now must also install your JDBC driver at the same global location (ie: into the TOMCAT_HOME/lib folder). If you don't do that, you will get a NoClassDefFoundErrors or a ClassNotFoundException or even a ClassCastException during your web application deployment.

This is not a limitation of Atomikos nor of Tomcat but of the J2EE class loading design that both Tomcat and Atomikos must follow.

The problem is that I cannot have all my value classes under that folder, of course.

Have I misenterperted the instruction?

Has anyone encountered this issue?

EHCache.xml

<cache name="myCache"  
       maxElementsInMemory="1000"  
       eternal="true"  
       overflowToDisk="false"  
       diskPersistent="false"  
       memoryStoreEvictionPolicy="LRU"  
        transactionalMode="xa"  
 />

Stack trace

net.sf.ehcache.CacheException: When configured copyOnRead or copyOnWrite, a Store will only accept Serializable values  
at net.sf.ehcache.store.compound.SerializationCopyStrategy.copy(SerializationCopyStrategy.java:47)  
at net.sf.ehcache.store.compound.Segment.potentiallyCopy(Segment.java:176)  
at net.sf.ehcache.store.compound.Segment.create(Segment.java:342)  
at net.sf.ehcache.store.compound.Segment.put(Segment.java:400)  
at net.sf.ehcache.store.compound.CompoundStore.put(CompoundStore.java:132)  
at net.sf.ehcache.transaction.StorePutCommand.execute(StorePutCommand.java:43)  
at net.sf.ehcache.transaction.xa.VersionAwareWrapper.execute (VersionAwareWrapper.java:68)  
at net.sf.ehcache.transaction.xa.EhcacheXAResourceImpl.prepareInternal(EhcacheXAResourceImpl.java:224)  
at net.sf.ehcache.transaction.xa.TransactionXARequestProcessor$XARequestCallable.call(TransactionXARequestProcessor.java:150)  
at net.sf.ehcache.transaction.xa.TransactionXARequestProcessor$XARequestCallable.call(TransactionXARequestProcessor.java:117)  
at net.sf.ehcache.transaction开发者_开发知识库.xa.XAThreadPool$MultiRunner.run(XAThreadPool.java:115)  
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)  
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)  
at java.util.concurrent.FutureTask.run(FutureTask.java:138)  
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)  
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)  
at java.lang.Thread.run(Thread.java:619)  
Caused by: java.lang.ClassNotFoundException: com.myCompany.testJTA.MyValue  
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)  
at java.security.AccessController.doPrivileged(Native Method)  
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)  
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)  
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)  
at java.lang.Class.forName0(Native Method)  
at java.lang.Class.forName(Class.java:247)  
at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:604)  
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575)  
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496)  
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732)  
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)  
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1947)  
at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:480)  
at net.sf.ehcache.Element.readObject(Element.java:796)  
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)  
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:25)  
at java.lang.reflect.Method.invoke(Method.java:597)  
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)  
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1849)  
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1753)  
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)  
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)  
at net.sf.ehcache.store.compound.SerializationCopyStrategy.copy (SerializationCopyStrategy.java:45)  
... 16 more  

It's important to add that due to an instruction I saw on the atomikos tutorial both Atomikos's jars and EHCache jars are under %TOMCAT_HOME%\lib

Classes from a web application (i.e. loaded by a WebappX classloader) aren't visible from the Common classloader (see the Apache Tomcat 6.0 - Class Loader HOW-TO ), which is why you get a CNFE.

Now, the question is, why do you put the EHCache JAR in the Common classloader? I don't think you need to. Package it at your web application level.

References

• Apache Tomcat 6.0 - Class Loader HOW-TO