[jboss-user] [Clustering/JBoss] - Re: Load-balance the invocation of a MBean in the cluster fr

[bstansberry@jboss.com]

First, the service implementation:


  | package org.jboss.test.cluster.invokerha;
  | 
  | import java.lang.reflect.Method;
  | import java.lang.reflect.InvocationTargetException;
  | import java.lang.reflect.UndeclaredThrowableException;
  | import java.security.Principal;
  | import java.util.Collections;
  | import java.util.HashMap;
  | import java.util.Map;
  | 
  | import org.jboss.ha.jmx.HAServiceMBeanSupport;
  | import org.jboss.invocation.Invocation;
  | import org.jboss.invocation.MarshalledInvocation;
  | import org.jboss.logging.Logger;
  | import org.jboss.security.SecurityAssociation;
  | import org.jboss.system.Registry;
  | 
  | public class HAService
  |    extends HAServiceMBeanSupport
  |    implements HAServiceRemote, HAServiceMBean
  | {
  |    private static final Logger log = Logger.getLogger(HAService.class);
  |    
  |    private int count = 0;
  | 
  |    private Map marshalledInvocationMapping;
  | 
  |    public void startService()
  |       throws Exception
  |    {
  |       super.startService();
  |       
  |       // Calulate method hashes for remote invocation
  |       Method[] methods = HAServiceRemote.class.getMethods();
  |       HashMap tmpMap = new HashMap(methods.length);
  |       for(int m = 0; m < methods.length; m ++)
  |       {
  |          Method method = methods[m];
  |          Long hash = new Long(MarshalledInvocation.calculateHash(method));
  |          tmpMap.put(hash, method);
  |       }
  |       marshalledInvocationMapping = Collections.unmodifiableMap(tmpMap);
  | 
  |       // Place our ObjectName hash into the Registry so invokers can resolve it
  |       Registry.bind(new Integer(serviceName.hashCode()), serviceName);
  |    }
  | 
  |    public void stopService()
  |       throws Exception
  |    {
  |       super.stopService();
  |       
  |       // No longer available to the invokers
  |       Registry.unbind(new Integer(serviceName.hashCode()));
  |    }
  | 
  |    /** 
  |     * Expose the client mapping
  |     */
  |    public Map getMethodMap()
  |    {
  |       return marshalledInvocationMapping;
  |    }
  | 
  |    /** 
  |     * This is the "remote" entry point
  |     */
  |    public Object invoke(Invocation invocation)
  |       throws Exception
  |    {
  |       log.info("Invoked");
  |       
  |       // Invoked remotely, inject method resolution
  |       if (invocation instanceof MarshalledInvocation)
  |       {
  |          MarshalledInvocation mi = (MarshalledInvocation) invocation;
  |          mi.setMethodMap(marshalledInvocationMapping);
  |       }
  |       Method method = invocation.getMethod();
  |       Object[] args = invocation.getArguments();
  |       
  |       log.info("Invocation of " + method);
  | 
  |       // Setup any security context (only useful if something checks it, this impl doesn't)
  |       Principal principal = invocation.getPrincipal();
  |       Object credential = invocation.getCredential();
  |       SecurityAssociation.setPrincipal(principal);
  |       SecurityAssociation.setCredential(credential);
  | 
  |       // Dispatch the invocation
  |       try
  |       {
  |          return method.invoke(this, args);
  |       }
  |       catch(InvocationTargetException e)
  |       {
  |          Throwable t = e.getTargetException();
  |          if( t instanceof Exception )
  |             throw (Exception) t;
  |          else
  |             throw new UndeclaredThrowableException(t, method.toString());
  |       }
  |       finally
  |       {
  |          // Clear the security context
  |          SecurityAssociation.clear();
  |       }
  |    }
  | 
  |    // Implementation of remote methods
  | 
  |    public String hello()
  |    {
  |       log.info("hello() invoked");
  |       return "Hello";
  |    }
  |    
  |    public String getClusterNode()
  |    {
  |       log.info("getClusterNode() invoked");
  |       return getHAPartition().getNodeName();
  |    }
  | 
  | }

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