IP_IN_QUEUE : Multiple Consumers

Hi,
This might be more of a AQ question but just wanted to check if anyone has had the requirement to use the IP_IN_QUEUE as a topic rather than a queue. i.e. use multiple consumers with the same consumer name receiving the same message. Is it advisable to create a custom topic as the point of entry as opposed to using the built in queue to forward to a topic.
regards,
Narayanan

Hi Narayanan,
Actually, IP_IN_QUEUE and IP_OUT_QUEUE are topics instead of queues because they can have multiple consumer names. The Document Routing ID is used to set the consumer name when B2B enqueues to IP_IN_QUEUE.
This sql statement is used to create the queue table.
execute dbms_aqadm.create_queue_table (queue_table => 'B2B.IP_QTAB', queue_payload_type => 'B2B.IP_MESSAGE_TYPE', multiple_consumers => TRUE);
Hope this helps,
Eng

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Single queue: concurrent processing of messages in multiple consumers

Hi,
I am new to jms . The goal is to process messages concurrently from a queue in an asynchronous listener's onMessage method by attaching a listener instance to multiple consumer's with each consumer using its own session and running in a separate thread, that way the messages are passed on to the different consumers for concurrent processing.
1) Is it ossible to process messsages concurrently from a single queue by creating multiple consumers ?
2) I came up with the below code, but would like to get your thoughts on whether the below code looks correct for what I want to accomplish.
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Properties;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.Session;
import javax.jms.TextMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.walmart.platform.jms.client.JMSConnectionFactory;
public class QueueConsumer implements Runnable, MessageListener {
public static void main(String[] args) {
   // Create an instance of the client
    QueueConsumer consumer1 = new QueueConsumer();
    QueueConsumer consumer2 = new QueueConsumer();
    try {
    consumer1.init("oms","US.Q.CHECKOUT-ORDER.1.0.JSON");   //US.Q.CHECKOUT-ORDER.1.0.JSON   is the queue name
    consumer2.init("oms","US.Q.CHECKOUT-ORDER.1.0.JSON");
    }catch( JMSException ex ){
    ex.printStackTrace();
    System.exit(-1);
    // Start the client running
    Thread newThread1 = new Thread(consumer1);
    Thread newThread2 = new Thread(consumer1);
    newThread1.start();newThread2.start();
    InputStreamReader aISR = new InputStreamReader(System.in);
          char aAnswer = ' ';
          do {
              try {
aAnswer = (char) aISR.read();
catch (IOException e)
// TODO Auto-generated catch block
e.printStackTrace();
} while ((aAnswer != 'q') && (aAnswer != 'Q'));
          newThread1.interrupt();
          newThread2.interrupt();
          try {
newThread1.join();newThread2.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
          System.out
.println("--------------------exiting main thread------------------------"+Thread.currentThread().getId());
        System.exit(0);
// values will be read from a resource properties file
private static String connectionFactoryName = null;
private static String queueName = null;
// thread safe object ref
private static ConnectionFactory qcf = null;
private static Connection queueConnection = null;
// not thread safe
private Session ses = null;
private Destination queue = null;
private MessageConsumer msgConsumer = null;
public static final Logger logger = LoggerFactory
.getLogger(QueueConsumer.class);
public QueueConsumer() {
super();
public void onMessage(Message msg) {
if (msg instanceof TextMessage) {
try {
System.out
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+ ((TextMessage) msg).getJMSMessageID());
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try {
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System.exit(-1);
while (!Thread.currentThread().isInterrupted()) {
synchronized (this) {
try {
wait();
} catch (InterruptedException ex) {
break;
* This method is called to set up and initialize the necessary Session,
* destination and message listener
* @param queue2
* @param factoryName
public void init(String factoryName, String queue2) throws JMSException {
try {
qcf = new JMSConnectionFactory(factoryName);
/* create the connection */
queueConnection = qcf.createConnection();
* Create a session that is non-transacted and is client
* acknowledged
ses = queueConnection.createSession(false,
Session.CLIENT_ACKNOWLEDGE);
queue = ses.createQueue(queue2);
logger.info("Subscribing to destination: " + queue2);
msgConsumer = ses.createConsumer(queue);
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msgConsumer.setMessageListener(this);
System.out.println("Listening on queue " +queue2);
} catch (Exception e) {
e.printStackTrace();
System.exit(-1);
private static void setConnectionFactoryName(String name) {
connectionFactoryName = name;
private static String getQueueName() {
return queueName;
private static void setQueueName(String name) {
queueName = name;

Hi Mark,
if the messages are sent with quality of service EO (=exactly once) you can add queues.
From documentation:
Netweaver XI -> Runtime -> Processing xml messages -> Queues for asynchronous message processing
...For incoming messages you set the parameter EO_INBOUND_PARALLEL from the Tuning category.
If more than one message is sent to the same receiver, use the configuration parameter EO_OUTBOUND_PARALLEL of the Tuning category to process messages simultaneously in different queues.
Transaction: SXMB_ADM
Regards
Holger

Could multiple consumers attach to a JMS queue simultaneously?

Could a JMS message queue have multiple consumers simultaneously? If can, how to implement that? My experiences showed that at any time there is only one consumer allowed for a JMS message queue. If a subsequent consumer tried to attach to the same queue, the following exception would be thrown out:
=====================================================
javax.jms.ResourceAllocationException: [C4073]: A JMS destination limit was reached. Too many Subscribers/Receivers for Queue : PhysicalQueue user=guest, broker=CTPLIT015PC:7676(1462)======================================================
On the contrary, definitely multiple consumers can be attached to the same Topic.

Well I need tor receive a message only once and this is why I would still have to use a queue. I have heard selector are slow so I do not want to use them.
Now the problem is since I am using onMessage event; the message push is like 150 message/second. While the message dequeue process always stuck up at 14 message/second.
I really need to increase the speed some good number may be 50 messages/second. I need to know whether I need to setup a threadmanager (with threadpool) in onMessage event, or I need to create multiple queue session.
If I create multiple queue session what would be the behavior of queue?
My main concern is to get this number up.
regards
shantanu

Multiple consumers of the same Queue

In the past my use of JMS queues has been limited to a single message producer and a single consumer. I am now looking at having multiple copies of the same consumer running for load balancing and failover purposes, and this leads me to what I think is a basic question. BTW, we're running OpenMQ 4.4u1.
I have messages being produced and saved in a single queue.
I then have a consumer program whose logic is something like this:
1. Create session with no transaction and CLIENT_ACKNOWLEDGE.
2. Receive message from queue.
3. Do some processing with message. Repeat processing attempts multiple times, if needed, until successful.
4. Once processing is successful, acknowledge message.
Assume that I am running multiple copies of the consumer in separate JVMs (or on separate servers, for that matter).
Here are my related questions.
1. If step 3 takes a long time (e.g., several minutes) can I be sure that only one instance of the consumer will receive the message?
2. If a consumer is in step 3 and a catastrophic failure occurs (e.g., the JVM or server it is running on crashes) the message will never be acknowledged, but the session will not be shut down in an orderly fashion, either. Will the message that was received but never acknowledged eventually be delivered to another copy of the consumer?
3. If step three takes a very long time (hours or days, rather than minutes), will the broker misinterpret this as a failure of the consumer and deliver the same message to another one of the consumers?
Thank you for reading and/or responding to this question.
Bill

1. If step 3 takes a long time (e.g., several minutes) can I be sure that only one instance of the consumer will receive the message?A queue message will only be delivered and consumed by 1 consumer.
2. If a consumer is in step 3 and a catastrophic failure occurs (e.g., the JVM or server it is running on crashes) the message will never be acknowledged, but the session will not be shut down in an orderly fashion, either. Will the message that was received but never acknowledged eventually be delivered to another copy of the consumer?Yes.
3. If step three takes a very long time (hours or days, rather than minutes), will the broker misinterpret this as a failure of the consumer and deliver the same message to another one of the consumers?No, as long as the consumer's Session or Connection are intact

Conditionally sending messages to multiple consumers

How would I best accomplish this requirement?
I have one system which produces messages
Multiple systems may want to consume those messages
I want the producer to be able to send messages conditionally
In one instance perhaps I send same message to each consumer
However in another case maybe I only want to send a message to consumers A and B
It would be OK if I could flag certain messages to be for certain consumers, and then those consumers only retrieve those messages designated to them. However I dont think this is possible as any such flag the consumer would have to read once it actually consumes the message and reads it, I dont think there is any way for the queue to make that decision for them.
So it sounds like what I need is a hybrid of point-to-point and publish-subscribe
I want a universal way to conditionally send messages to one or more consumers, and the conditions are dynamic.
Any suggestions?
Must it be a PTP with separate queue for every application?

lozina wrote:
Interesting... message filters. I like it.
So with this approach, I can send some messages to everyone, and other messages I can have tailored to specific subscribers?pretty much.
But the subscriber does not actually have to "fetch" each message to determine if the message is meant for him or not, right? When using message filters this act at the queue, not at the client? Basically I want to avoid a client downloading 1,000 messages only to find out none of them are for him. unfortunately, that's probably up to the implementation. the implementation may choose to work that way (download every message and check it), or it may have a way of applying the filter at the server. however, the filters work only on the message properties, so the impl may be able to just get message headers and filter w/out getting the entire message. you'll have to test with the jms impl you are planning on using and see how that works.
Thanks!
[Edit] these are called Message Selectors right? yes.
And looks like they are specified at the time the client looks up the queue in JNDI?yes, these are provided at subscription time.
Now is this limited to publish-subscribe?no you can use selectors when subscribing to a queue as well. but, queues won't scale very well to lots of consumers (and are hard to manage with dynamic numbers of consumers).

Queue: one producer vs multiple consumers

Hi,
This may be a simple question. In my application, I have a master/multiple slaves queue architecture. So the master enqueues messages. Each message is adressed to only one slave. Since all the slaves are waiting after queue elements, they all should receive the message and all dismiss it but one, the destinator. Apparently, it is not working like that. Once the message is dequeued by a slave, it is no more available in the queue and the others are not notified. Is that right?
I could use a seperate queue for each slave, but when it comes to be 100 slaves, I find it a but heavy to manage hundred queues. I tried instead to do a router-like architecture. Everyone is listening and for each message they all verify who is the destinator. Only the destinator processes the message and the other ones simply dismiss it. Is there a way for me to implement that?
Joe

It actually sounds like a fairly dicey problem, depending on your need for response times and total messaging bandwidth. Many of the issues seem to revolve around multiple producers and consumers wanting simultaneous read and write access to a continuously changing entity. At least that's how it sounded to me, that all the consumers are independent and should be allowed to consume their own messages just as soon as they're able to notice them.
For example:
Consumer #3 performs a preview and discovers that there's a message waiting at position #9. In order to pull it out of the queue, it must first dequeue the first 8 messages in line. Then after dequeueing its own message, it must re-enqueue those 1st 8 messages, this time using "Enqueue at Opposite End" to restore the original sequence.
However, before it can finish re-enqueue'ing those 8, Consumer #11 performs a preview and discovers that there's a message at (apparent) position 4. This really *should* be position 12, but how can Consumer #11 know what #3 is in the middle of?
Meanwhile, one of Consumer #3's 8 messages is addressed to Consumer #11, and it's actually quite important that Consumer #11 gets this one first instead of the one that it just found for itself
And so on...
Now, some (most? all?) of this kind of conflict can be resolved through the use of semaphores, but the penalty is that whenever any Consumer is accessing the shared queue, 100's of other Consumers are stuck waiting their turn. And so all the independence and parallelism you were after in the first place with the producer / consumer pattern starts slipping away...
I haven't personally built an app around a massively parallel messaging architecture. I hope someone who has gets involved here because I'd like to learn how it's done. I'd wager there are a few different elegant solutions, but all I can manage to think of are the pitfalls.
-Kevin P.

Messages from topic to multiple consumers are not ordered the same way

Hi,
We have a distributed topic. The message producer is a multi-threaded/connection producer (OSB in our case).
On the other side of the DT there are single connection consumers.
Our problem is that the consumers sometimes recieve the messages in different order:
Consumer A recieves message N and then N+1 (correct behaviour).
Consumer B recieves message N+1 and then N (correct behaviour).
This does not happen all the time. Most of the time the order is correct (99.9..%).
We also noticed that the message timestamp for message N and N+1 is the same.
This creates a problem for our system since both consumers must get the messages in the same order.
We cannot use UOO.
Any idea if this is a correct behavior for DT?
Any idea how to make the messages get to all consumers in the same order without using UOO?
Thanks,

Hi,
Hmm. You may have run into some new Bug given since "message timestamp for message N and N+1 is the same". First, let's dot our I's and cross our Ts to make sure that the system is setup in a way that will give you good ordering in the first place:
- Always use the same producer instance for each sequential send, and ensure that the producer's connection factory has "load balance" set to false. Note that OSB may be using a pool of producers implicitly for your sending app underneath-the-covers, which could lead to out-of-order, as different producers can load balance to different servers in your cluster. (I'm not sure how to check for this - if you provide a code snippet, I may be able to tell if this is happening.)
- Ensure that you only ever have a single thread processing the subscription - if you're using MDBs to receive from the subscription, then you need to ensure the MDB is setup to only startup a single thread (use a thread pool of size and/or set max-beans-in-free-pool to one)
- To account for out-of-order after app message processing failures (redelivery) with async consumers or MDBs, you need to (A) never configure redelivery delays, and (B) ensure the connection factory Maximum Messages setting is tuned down to 1 (it's default is 10).
I don't know how to do the above with OSB, which tends to layer it's own configuration on top of WL JMS configuration.
Assuming that you've assured all of the above, then you may have run into some sort of bug and I recommend filing a request with Oracle Support. In the mean-time, you might want to explore alternatives:
- Are you certain that you can't use UOO? It would be interesting to know why. This is a widely used feature (even by OSB itself), and it may be that you can enable it without any code change, plus, even if a code change is required, such changes tend to be isolated and small. In your use case, it looks like you may be able to configure a default UOO on the distributed topic itself (http://docs.oracle.com/cd/E11035_01/wls100/wlsmbeanref/core/index.html) - no code change needed - so that every destination member of your distributed destination will simply ensure that each new message is given the same UOO (a UOO that's particular to that member). OSB may provide some equivalent knob. Alternatively, you can code up your app so that each of your producers sets a useful UOO on each message.
- I assume you're using a replicated distributed topic (RDT). If there actually is a bug, then it would likely have something to do with the RDT's internal forwarders. If your consumers are MDBs or the SOA RA Adapter, then a simple alternative may be to use a Partitioned Distributed Topic (PDT) instead -- PDTs have no forwarders, and the MDB and the SOA RA Adapter can work with them transparently. If your consumers are neither of these, then working with a PDT will likely require that you use extensions (an advanced path that you may not want to take the time to follow).
Tom

Multiple consumers dequeue

I use a rule based subscription to enqueue message in a queue, because I need to specify which consumer can dequeue the message, but I also need to let the message dequeued by a single consumer.
In other words, while enqueuing I specify the consumers which can dequeue the message, but only one of them can dequeue the message - the first which fetches first.
Does anyone know a solution to this problem?
Thanks a lot
Antonio

So it seems the solution is to explicity assign the message to a specific consumer during enqueuing, using the recipient_list parameter of the specify message properties.
Anyway, thanks for the answer.
Bye
Antonio

Multiple consumers for AQ-Adpater

Hi,
I want to use a generic queue that will be used by multiple BPEL process. Is there was to specify the channel rule OR AQ-adapter rule so that a content based routing can be done to specific BPEL processes. What are the different options that Adapters provide to achieve this? Is there a concept of dead letter channel/queue for the messages not satisfying any rules?
Thanks,.
Anil

Thanks for info. Where do I set the property or the header variable for a JMS message in an adapter ?
Should I set it using the adapter tab in invoke OR use the property tab in the adapter partnerlink when sending out the message?
I have set the following in the invoke before producing the message and dropping on the queue
<invoke name="Invoke_1" partnerLink="adapt"
portType="ns1:Produce_Message_ptt"
operation="Produce_Message"
inputVariable="Invoke_1_Produce_Message_InputVariable"
bpelx:inputHeaderVariable="Sender"/>
On the receive side I have the message selector configured for the adapter as follows:
<jca:operation
ActivationSpec="oracle.tip.adapter.jms.inbound.JmsConsumeActivationSpec"
DestinationName="dattjndi"
UseMessageListener="false"
MessageSelector="Sender=AdaptationRequest"
PayloadType="TextMessage"
OpaqueSchema="false" >
</jca:operation>
Where AdaptationRequest is the value for the Sender variable which will be used to filter the message. But this does not work. the messages are still not consumed. What could be the problem?
Thanks,
Anil

Multiple Consumers on a set of Queues

Is there any better way of implementing this other than polling all the queues?
or is there are any 3rd party library, which can do this already.
Regards
Gopal

Sure, you use wait/notify. The consumer syncrhonizes on a suitable monitor, then checks all the queues, and waits if they are all empty. Producers for any of the queues notify all the consumers.
You'd probably want the consumer threads to check the queues cyclically, rather than starting at the beginning each time they find an object so that they don't favour one queue excessively.

Propagate data point to multiple consumers? I'm probably overcomplicating this.

Please see the attached screencap.
The DAQ assistant in the first case structure is taking a lot of measurements from a local cDAQ chassis. One of those data points (#15) needs to be extracted (hence the select signals) and then merged with the signals from three remote (ethernet connected) chassis.
The issue that I'm having is that the data point, due to the fact that the chassis and consumers aren't running in any specific order or sync, sometimes just isn't there when the consumer loops run and it reads a 0 rather than the value. This causes the test stand to think it lost hydraulic pressure and call for a shutdown.
I'm aware someone will tell me to wire the error from each DAQ assistant to the next, but that creates a massive 6.5 second loop time, which is unacceptable. The chassis have to remain independent to keep execution time down.
I'm looking for a way to 'catch' that #15 data point and hold it for the consumers to use until the next iteration where it is replaced with the new value. I'm not sure if Collector is what I'm looking for, or some sort of data copy, or a register. If this was a PLC I'd know what to do with it.
Thanks in advance.
Still confused after 8 years.
Solved!
Go to Solution.
Attachments:
lostpoints.jpg ‏246 KB

As I see you are using LV in a wrong way. Why don't you run the DAQ tasks in independent while loops? You could use the same Queue, and you can add time stamps to every data package (or also a label to show the source) created in the several Producer loops. In your single Consumer loop you can just decide what to do with the data depending on the label (save to File,etc...).
Other big problem: do not use DAQ Assistant! It is OK for quick testing, but not for real application! These Express VIs initializes and closes your hardware at EVERY while loop iteration.
You should use proper DAQmx VIs: initialize your HW resources BEFORE the while loop, do your DAQ inside the loop, and close HW components when you stop the application.
There are many examples shipped with LabVIEW, have a look how to use DAQmx VIs. Also, this way you avoid the silly dynamic data wires...Much easier to live with Double arrays

Jms queue multiple consumers

Hi,
I am new to the JMS queue concept. I have two BPEL processes each having JMS adapter for consuming the data from the same queue. How do i differentiate which consumer consumes which data that is put into the queue. Is there any field in the queue that decides which consumer has to consume the message.
Just to add to above query, if the message goes to all the consumers, is there any way that i put some logic there to let only the eligible consumer actually process that message.
It would be helpful if i get any documentation on this.
Thanks in advance for the Help!
Edited by: Marius J on Jun 2, 2009 7:38 AM

Thanks Sahil and JDT. Thanks for the response.
Sahil,
I was able to proceed the way u specified. I am using AQ. How do i send the corrid while enqueuing the data in the queue. I am using the following command to enqueue the data.
CONNECT aq_user/aq_user@tsh9i
DECLARE
l_enqueue_options     DBMS_AQ.enqueue_options_t;
l_message_properties DBMS_AQ.message_properties_t;
l_message_handle      RAW(16);
l_event_msg           AQ_ADMIN.event_msg_type;
BEGIN
l_event_msg := AQ_ADMIN.event_msg_type('REPORTER', 1, 2);
DBMS_AQ.enqueue(queue_name          => 'aq_admin.event_queue',
enqueue_options     => l_enqueue_options,
message_properties => l_message_properties,
payload             => l_event_msg,
msgid               => l_message_handle);
COMMIT;
END
But, as per your inputs, we need to send corrid in order to meet my requirement. Can u please guide me regarding this.
Thanks again
Regards,
MJ
Edited by: Marius J on Jun 4, 2009 7:39 AM

(Multiple Consumers) vs (Multi-threaded Message Processing after reception)

Hi,
The question pertains to the following scenario:
1. A single input gateway (queue) for messages.
2. Messages arriving from different systems. High incidence during specific periods
3. Message should be processed in near real-time as and when it arrives.
4. A non-polling (async) client.
I'd thought of two diff approaches for it:
1> Have a lightweight single-threaded message consumer -
init connection etc and register a listener (both msg and excep).
start connection . wait indefinitely
Listener onMessage creates new thread for working and returns.
Worker thread - parses xml in message and

Here is the new code:
     public static void writeXML(DataOutputStream out, String xml) {
          byte[] byteArray = xml.getBytes();
          try {
               int length = byteArray.length;
               out.writeInt(length);
               out.write(byteArray);
               out.flush();
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
     public static String receiveXML(DataInputStream in){
          int id = (new Date()).hashCode();
          try {
               int lengthToRead = in.readInt();
               byte[] byteRead = new byte[lengthToRead];
               in.readFully(byteRead);
               String s = new String(byteRead);
               return (s);
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
          return null;
     }P.S. By changing the code I meant that I was sending the full byte array instead of sending parts as sabre suggested.

How do I build a producer/consumer VI with multiple consumers?

I’m studying for the CLD using this document as a base:
Certified LabVIEW Developer (CLD) Certification and Exam Overview
One of the requirements in that document has me stumped:
6. Select a producer/consumer (events) design pattern to respond to user interface events in the producer loop and defer the processing of the event to one or more consumer loops
I start with LabVIEW's producer/consumer (events) template and give it two consumer loops. However, each event only gets to one of the two loops, not both, as you can see in my attached example VI 1_producer_2_consumers.vi.
I would try LabVIEW notifiers, but I read that a notifer is not guaranteed to reach the consumer loops because they are not queued. I would try user-defined user events which might work, but they are not part of the CLD.
What’s the way to complete requirement 6 above?
Solved!
Go to Solution.
Attachments:
1_producer_2_consumers.vi ‏19 KB

bmihura wrote:
However, each event only gets to one of the two loops, not both, as you can see in my attached example VI 1_producer_2_consumers.vi.
you must have a 'queue' for each consumer and you were not properly stopping the loops with user interface (using error handling inefficiently, you will get dinged for it on the CLD)...
Spoiler (Highlight to read)
Attachments:
1_producer_2_consumersMOD.vi ‏23 KB

Configure # of JMS consumers for WebServices over JMS Transport

I'm using WebLogic Server 9.2. My Web Services are using JMS Transport.
10,000 Web Services requests are submitted to the Web Services JMS queue at the same time. Processing time seems a little slow. In the Admin console, monitoring info of the JMS queue shows the Consumers is 4 and Consumers High is 6.
I want to scale Web Services processing by increasing the number of JMS consumers that transform JMS request messages into Web Services requests. Does anyone have an idea to configure it?

Hi,
I don't think the number of consumers for a service is configurable. There is a single consumer for each service. Well, there is another consumer for interop purposes, which is irrelevant to our discussion here.
You may be aware that multiple consumers reading from the same queue would result in requests being processed in parallel, which means the order that the requests are processed might be different from the order that they are put into the queue.
For applications where the order of processing the requests to the same web service is not important, it probably makes sense to have an option of configuring multiple consumers. But this is no such option right now.
Regards,
Dongbo, BEA

IP_IN_QUEUE : Multiple Consumers

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