Disconnecting from a weblogic JMS

Question

Right now my disconnection from a weblogic JMS server looks like this

import java.util.Hashtable;
import javax.jms.*;
import javax.naming.*;
import javax.transaction.*;
import java.util.Vector;
import javax.rmi.PortableRemoteObject;
import clojure.java.api.Clojure;
import clojure.lang.IFn;
import org.apache.log4j.Logger;
import weblogic.jndi.*;

public class WebLogicListener implements MessageListener, ExceptionListener{
  public InitialContext ctx;
  public TopicConnectionFactory conFactory;
  public TopicConnection tCon;
  public TopicSession tSession;
  public TopicSubscriber tSub;
  public Boolean development;
  public Topic topic;
  /*clojure function objects*/
  public IFn publish;
  public IFn close;
  public IFn incrementMetric;
  public IFn logMessage;
  public IFn resync;

  public Object channel;
  public ExceptionListener exception;
  public String topicName;
  public String subName;
  public String username;
  public String password;
  public String clientId;
  public String factoryJNDI;
  public String topicJNDI;
  public Vector nms;
  public Hashtable<Object,Object> env;
  public boolean running = false;

  public WebLogicListener (String topicName, String host, String username, String password, String factoryJNDI,
                           String topicJNDI, String clientId, String subName, String ns, String fnName,
                           boolean development, Vector nms){
    this.username = username;
    this.password = password;
    this.clientId = clientId;
    this.topicName = topicName;
    this.subName = subName;
    this.development = development;
    this.topicJNDI = topicJNDI;
    this.factoryJNDI = factoryJNDI;
    this.nms = nms;
    /*Clojure interop handlers*/
    IFn chan = Clojure.var("clojure.core.async", "chan");
    resync = Clojure.var("cenx.baldr.api", "resync!");
    publish = Clojure.var(ns, fnName);
    incrementMetric = Clojure.var(ns, "log-metric");
    logMessage = Clojure.var (ns, "log-message");
    close = Clojure.var("clojure.core.async","close!");
    /*populate envrionment*/
    env = new Hashtable<Object,Object>();
    env.put(Context.PROVIDER_URL, host);
    env.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
    env.put(Context.SECURITY_PRINCIPAL, username);
    env.put(Context.SECURITY_CREDENTIALS, password);
    env.put("weblogic.jndi.createIntermediateContexts", "true");
    /*open communication channel for clojure daemon*/
    channel = chan.invoke();
  }

  private void initListener() throws JMSException, NamingException{
    try{
      if (!running && !development){
        ctx = new InitialContext(env);
        topic = (Topic) ctx.lookup(topicJNDI);
        conFactory =  (TopicConnectionFactory)PortableRemoteObject.narrow(ctx.lookup(factoryJNDI), TopicConnectionFactory.class);
        tCon = (TopicConnection) conFactory.createTopicConnection();
        tCon.setExceptionListener(this);
        tCon.setClientID(clientId);
        tSession = (TopicSession) tCon.createTopicSession(false, 1);
        tSub = tSession.createDurableSubscriber(topic, subName);
        tSub.setMessageListener(this);
        tCon.start();
        running = true;
      }else{
        if (running){
          logMessage.invoke("error", String.format("Listener is already running"));
        }
        if (development){
          logMessage.invoke("info", "Running in development mode, no connection established");
        }
      }
    } catch(Exception e){
      logMessage.invoke("error", String.format("Unable to start listener \n %s", e.toString()));
    }
  }

  public void startListener(){
    if (!development && env != null){
      try {
        initListener();
      }catch(Exception e){
        logMessage.invoke("error", String.format("Unable to start Listener \n %s", e.toString()));
      }
    } else {
      if (development){
        logMessage.invoke("info", "Running in development mode, no connection established");
      }
      if (env == null){
        logMessage.invoke("error", "Environment variable is null");
      }
    }
  }

  ///Closes the JMS connection and the channel
  public void stopListener(){
    if (!development){
      try{
        tSub.close();
        tSession.close();
        tCon.close();
        incrementMetric.invoke("JMS-disconnect-count");
      }catch(Exception e){
        logMessage.invoke("error", String.format("Error while stopping the listener \n %s", e.toString()));
      }finally{
        running = false;
      }
    } else {
      logMessage.invoke("info", "Listener not started, running in development mode");
    }
  }

  public Object getChannel(){
    return channel;
  }

  //re-initializes the channel in case of error
  public void initializeChannel(){
    if (channel == null){
      IFn chan = Clojure.var("clojure.core.async", "chan");
      channel = chan.invoke();
    } else {
      logMessage.invoke("info", "Channel is already initialized");
    }
  }
  //accessors for debugging

  public void closeSubscription(){
    try{
      tSub.close();
    }catch (Exception e){
      logMessage.invoke("error", "unable to close topic subscription");
      logMessage.invoke("error", e.toString());
    }
  }

  public void closeSession(){
    try{
      tSession.unsubscribe(subName);
      tSession.close();
    }catch (Exception e){
      logMessage.invoke("error", "unable to close topic session");
      logMessage.invoke("error", e.toString());
    }
  }

  public void closeConnection(){
    try{
      tCon.close();
    }catch (Exception e){
      logMessage.invoke("error", "unable to close topic connection");
      logMessage.invoke("error", e.toString());
    }
  }

  public void closeContext(){
    try {
      ctx.close();
    }catch (Exception e){
      logMessage.invoke("error", "unable to close context");
      logMessage.invoke("error", e.toString());
    }
  }

  public Boolean isRunning(){
    return running;
  }

  public Context getContext (){
    return ctx;
  }

  public TopicConnectionFactory getFactory (){
    return conFactory;
  }

  public TopicConnection getTopicConnection (){
    return tCon;
  }

  public TopicSession getTopicSession (){
    return tSession;
  }

  public Boolean getDevelopmentMode(){
    return development;
  }

  public TopicSubscriber getTopicSubscriber (){
    return tSub;
  }

  public Topic getTopic (){
    return topic;
  }

  /*Interface methods*/

  public void onMessage(Message message){
    publish.invoke(channel, message);
  }
  /*attempt a resync after an exception connection*/
  private void resync(){
    resync.invoke(nms);
  }

  private void attemptReconnect() throws Exception{
    if (!development){
      //clean up any portions of the connection that managed to establish
      stopListener();
      //incase of stopListener exceptioning out set running to false
      running = false;
      do{
        try{
          initListener();
          if (running){
            resync();
          }
        }catch(Exception e){
          logMessage.invoke("error",
                            String.format("Unable to establish connection to JMS server \n %s", e.toString()));
        }finally{
          Thread.sleep(30000);
        }
      } while (!running);
    } else {
      logMessage.invoke("info", "Running in development mode, no connection established");
    }
  }

  public void onException(JMSException e){
    logMessage.invoke("error",
                      String.format("A JMS Exception has occurred, attempting to re-establish topic connection \n %s", e.toString()));
    try{
      incrementMetric.invoke("JMS-disconnect-count");
      attemptReconnect();
    }catch(Exception g){
      logMessage.invoke("error",
                        String.format("Unable to start Listener \n %s", g.toString()));
    }
  }

  /* Test functions */
  public void testException() throws JMSException{
    onException(new JMSException("testing exception function"));
  }

  public void testChannel (String message){
    if (development){
      publish.invoke(channel, message);
    }
  }
}

When I create the connection I use netstat to check if the server is connected

netstat -an | grep 8001 tcp 0 0 ip-address:59730
ip-address:8001 ESTABLISHED

Then I call my .stopListener in addition to the .closeContext method and go back to check my connection again with netstat and I get the same result

netstat -an | grep 8001 tcp 0 0 ip-address:59730
ip-address:8001 ESTABLISHED

Why would closing the session, subscriber, and connection not destroy the connection to the JMS server. The documentation I've found hasn't given me any explanation of why I cannot destroy the connection fully.

Answer 1

I am not sure you are approaching this correctly. I see you have an exception listener on the connection.

On weblogic, the listener will get invoked many times for each error event, so you should not do attemptReconnect on each call. It would get called once for every consumer you registered and once for each connection it monitored. You should only disconnect if the exception represented a ServerConnectionLost.

Also, in the error handler you only have to close the connection. If you did connection.close(), that would close the session and the listeners too. No need to close them in reverse order like you do.

And another thing. You should not have "development" or "debug" or "test" code in your production code.

That part that says "if (!development && env != null){" ... You should not do that.

Now back to your question, why is the actual connection not closed. I see you are doing

try{
    tSub.close();
    tSession.close();
    tCon.close();
    incrementMetric.invoke("JMS-disconnect-count");
} catch...

If tSub.close() or tSession.close() were to error out, your connection would never get closed. Wrap each one in an independent try / catch.