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From Christian Posta <christian.po...@gmail.com>
Subject Re: standard jms code can not receive message from queue
Date Fri, 27 Sep 2013 14:54:44 GMT
You must not rely on receiveNoWait to always return a message. What the
method does is check whether any messages have been dispatched to the
consumer AND are *waiting on the consumer's prefetch* This is not the case
in your test above as it takes a few cycles for the broker to dispatch over
your network to get to the consumer's prefetch.

Please do a search of the list ahead of time as this has been succinctly
answered before by Tim:

http://activemq.2283324.n4.nabble.com/consumer-receiveNoWait-question-td4656435.html#a4656615

This behavior follows the JMS spec, but I realize different providers may
have implemented this differently, so if you try with prefetch == 0 on the
consumer side, it should actively poll the broker ... which is probably
what you're looking for.



On Fri, Sep 27, 2013 at 7:38 AM, zbc <zhebincong@163.com> wrote:

> please run following test:
>
> *package com.conceptwave.servicedesigner;
>
> import java.util.Hashtable;
>
> import javax.jms.JMSException;
> import javax.jms.Message;
> import javax.jms.Queue;
> import javax.jms.QueueConnection;
> import javax.jms.QueueConnectionFactory;
> import javax.jms.QueueReceiver;
> import javax.jms.QueueSender;
> import javax.jms.QueueSession;
> import javax.jms.Session;
> import javax.naming.Context;
> import javax.naming.InitialContext;
> import javax.naming.NamingException;
>
> import junit.framework.Assert;
>
> import org.junit.Before;
> import org.junit.Test;
>
> public class test {
>         /**
>          * put a test message to queue before test case run.
>          */
>         @Before
>         public void setup() {
>                 InitialContext ctx = null;
>                 QueueConnection con = null;
>                 QueueSession queueSession = null;
>                 QueueSender sender = null;
>                 try {
>                         Hashtable env = new Hashtable();
>                         env = new Hashtable();
>                         env.put(Context.INITIAL_CONTEXT_FACTORY,
>
> "org.apache.activemq.jndi.ActiveMQInitialContextFactory");
>                         env.put(Context.PROVIDER_URL,
> "tcp://localhost:61616");
>                         ctx = new InitialContext(env);
>                         QueueConnectionFactory fac =
> (QueueConnectionFactory) ctx
>                                         .lookup("ConnectionFactory");
>                         con = fac.createQueueConnection();
>                         queueSession = con.createQueueSession(false,
>                                         Session.AUTO_ACKNOWLEDGE);
>                         con.start();
>                         sender = queueSession.createSender((Queue) ctx
>                                         .lookup("dynamicQueues/queue1"));
>                         sender.send(queueSession.createTextMessage("test
> message"));
>                 } catch (Exception e) {
>                         e.printStackTrace();
>                 } finally {
>                         try {
>                                 sender.close();
>                                 queueSession.close();
>                                 con.close();
>                                 ctx.close();
>                         } catch (JMSException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         } catch (NamingException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         }
>                 }
>         }
>
>         /**
>          * the receiver must sleep enough time after it is created in
> order to
>          * receive the message in the queue.
>          */
>         @Test
>         public void test1() {
>                 InitialContext ctx = null;
>                 QueueConnection con = null;
>                 QueueSession queueSession = null;
>                 QueueReceiver receiver = null;
>                 try {
>                         Hashtable env = new Hashtable();
>                         env = new Hashtable();
>                         env.put(Context.INITIAL_CONTEXT_FACTORY,
>
> "org.apache.activemq.jndi.ActiveMQInitialContextFactory");
>                         env.put(Context.PROVIDER_URL,
> "tcp://localhost:61616");
>                         ctx = new InitialContext(env);
>                         QueueConnectionFactory fac =
> (QueueConnectionFactory) ctx
>                                         .lookup("ConnectionFactory");
>                         con = fac.createQueueConnection();
>                         queueSession = con.createQueueSession(false,
>                                         Session.AUTO_ACKNOWLEDGE);
>                         con.start();
>                         receiver = queueSession.createReceiver((Queue) ctx
>                                         .lookup("dynamicQueues/queue1"));
>
>                         // in order to receive the message from queue,
> must sleep enough
>                         // time
>                         Thread.sleep(500);
>                         // the message can be received successfully after
> sleep.
>                         Message result = receiver.receiveNoWait();
>                         Assert.assertNotNull(result);
>                 } catch (Exception e) {
>                         e.printStackTrace();
>                 } finally {
>                         try {
>                                 receiver.close();
>                                 queueSession.close();
>                                 con.close();
>                                 ctx.close();
>                         } catch (JMSException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         } catch (NamingException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         }
>                 }
>         }
>
>         /**
>          * the receiver never get the message IMMEDIATELY after it is
> created.
>          *
>          * @throws Exception
>          *             to junit.
>          */
>         @Test
>         public void test2() throws Exception {
>                 // sleep enough time to make sure the test message is
> really put into
>                 // the queue.
>                 Thread.sleep(5000);
>
>                 InitialContext ctx = null;
>                 QueueConnection con = null;
>                 QueueSession queueSession = null;
>                 QueueReceiver receiver = null;
>                 try {
>                         Hashtable env = new Hashtable();
>                         env = new Hashtable();
>                         env.put(Context.INITIAL_CONTEXT_FACTORY,
>
> "org.apache.activemq.jndi.ActiveMQInitialContextFactory");
>                         env.put(Context.PROVIDER_URL,
> "tcp://localhost:61616");
>
>                         // repeatedly try to receive message, but you
> NEVER get it!!
>                         for (int i = 0; i < 100; i++) {
>                                 ctx = new InitialContext(env);
>                                 QueueConnectionFactory fac =
> (QueueConnectionFactory) ctx
>
> .lookup("ConnectionFactory");
>                                 con = fac.createQueueConnection();
>                                 queueSession =
> con.createQueueSession(false,
>                                                 Session.AUTO_ACKNOWLEDGE);
>                                 con.start();
>                                 receiver =
> queueSession.createReceiver((Queue) ctx
>
> .lookup("dynamicQueues/queue1"));
>                                 // no sleep after the receiver is created
>                                 // Thread.sleep(500);
>                                 Message result = receiver.receiveNoWait();
>                                 // you CAN NOT get the message in the
> queue.
>                                 Assert.assertNull(result);
>                         }
>                 } catch (Exception e) {
>                         e.printStackTrace();
>                 } finally {
>                         try {
>                                 receiver.close();
>                                 queueSession.close();
>                                 con.close();
>                                 ctx.close();
>                         } catch (JMSException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         } catch (NamingException e) {
>                                 // TODO Auto-generated catch block
>                                 e.printStackTrace();
>                         }
>                 }
>         }
>
> }*
>
>
>
>
> --
> View this message in context:
> http://activemq.2283324.n4.nabble.com/standard-jms-code-can-not-receive-message-from-queue-tp4671868p4671901.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>



-- 
*Christian Posta*
http://www.christianposta.com/blog
twitter: @christianposta

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