3 Replies Latest reply on Apr 4, 2008 3:03 PM by Galder Zamarreño

    JBoss NullPointerException when custom Interceptor is being

    Alexey Zheludkov Newbie

      Hi everybody,

      I already published this question in previous topic http://www.jboss.com/index.html?module=bb&op=viewtopic&t=128146 but did not received any responses.


      Does anybody have any idea why it happens?

      According to FAQ http://wiki.jboss.org/wiki/Wiki.jsp?page=ClusteringFAQ in order to get load balancing I created my custom InvokerInterceptor and modified standardjboss.xml to replace JBoss's invoker by my custom one.
      Load balancing works almost fine, but sometimes when my client makes ejb calls via threads I'm getting exceptions like this.

      java.lang.NullPointerException
      at org.jboss.invocation.unified.interfaces.UnifiedInvokerHAProxy.invoke(UnifiedInvokerHAProxy.java:186)
      at org.jboss.invocation.InvokerInterceptor.invokeInvoker(InvokerInterceptor.java:365)
      at org.jboss.invocation.InvokerInterceptor.invoke(InvokerInterceptor.java:197)
      at org.jboss.proxy.ejb.RetryInterceptor.invoke(RetryInterceptor.java:176)
      at org.jboss.proxy.TransactionInterceptor.invoke(TransactionInterceptor.java:61)
      at org.jboss.proxy.SecurityInterceptor.invoke(SecurityInterceptor.java:70)
      at org.jboss.proxy.ejb.StatelessSessionInterceptor.invoke(StatelessSessionInterceptor.java:112)
      at org.jboss.proxy.ClientContainer.invoke(ClientContainer.java:100)
      at $Proxy74.submitJob(Unknown Source)
      at com.framework.system.cluster.ClusterJobSubmitter$RunInThread.run(ClusterJobSubmitter.java:111)
      at java.lang.Thread.run(Thread.java:595)


      It looks like client fails to get through a chain of interceptors.

      Here is a code:
      1. Custom Invoker (Jar with compiled invoker was placed in jboss-4.2.2.GA\server\all\lib).

      package com.framework.jboss;
      import org.jboss.invocation.*;
      public class CustomInvokerInterceptor extends InvokerInterceptor {
      public boolean hasLocalTarget(Invocation invocation) {
      return false;
      }
      }

      2. Modified piece of standardjboss.xml

      <invoker-proxy-binding>
      clustered-stateless-unified-invoker
      <invoker-mbean>jboss:service=invoker,type=unifiedha</invoker-mbean>
      <proxy-factory>org.jboss.proxy.ejb.ProxyFactoryHA</proxy-factory>
      <proxy-factory-config>
      <client-interceptors>

      org.jboss.proxy.ejb.HomeInterceptor
      org.jboss.proxy.SecurityInterceptor
      org.jboss.proxy.TransactionInterceptor
      org.jboss.proxy.ejb.SingleRetryInterceptor
      <interceptor call-by-value="false">org.jboss.invocation.InvokerInterceptor
      <interceptor call-by-value="true">org.jboss.invocation.MarshallingInvokerInterceptor


      org.jboss.proxy.ejb.StatelessSessionInterceptor
      org.jboss.proxy.SecurityInterceptor
      org.jboss.proxy.TransactionInterceptor
      org.jboss.proxy.ejb.SingleRetryInterceptor
      <interceptor call-by-value="false"> com.framework.jboss.CustomInvokerInterceptor
      <interceptor call-by-value="true">org.jboss.invocation.MarshallingInvokerInterceptor

      </client-interceptors>
      </proxy-factory-config>
      </invoker-proxy-binding>

      3. Client's code snippet:

      public class ClusterJobSubmitter {

      private JobSubmitterHome m_home = null; // ejb home
      . . . . . .
      public void runJob(Ticket jt) throws Exception {
      synchronized (this){
      if (m_home==null) {
      createEjbHome();
      }
      }
      RunInThread runner = new RunInThread(jt);
      Thread thread = new Thread(runner);
      thread.start();
      }

      class RunInThread implements Runnable {
      Ticket m_jt=null;

      public RunInThread(Ticket jt) {
      m_jt= jt;
      }

      public void run() {
      JobSubmitter execute = null; \\ ejb remote stab
      try {
      synchronized (m_home){
      execute = (JobSubmitter) m_home.create();
      }
      execute.submitJob(m_jt);
      } catch (Exception ex) {
      ex.printstacktrace();
      }
      }
      }
      }