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Message
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| Praveen |
 Posted: Wed Feb 12, 2003 2:39 am Post subject: How to get the messages with the proper MessageId |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Hi All,
While putting the messages I am setting the messageId as inMsg.messageId = MQC.MQCI_NONE, now I want to get the response by checking the particular messageId, how should I do it?.
If I do like this while getting the message, will it work?
gmo.matchOptions = MQC.MQMO_MATCH_MSG_ID, is it going to give me the correct output for which I had sent?.
_________________
Thanks,
Praveen K |
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| vennela |
| Posted: Wed Feb 12, 2003 6:33 am Post subject: |
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Jedi Knight
Joined: 11 Aug 2002
Posts: 4055
Location: Hyderabad, India
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Praveen:
Take a look at the reply to a post made bu Duncan(point 2). That would explain you how to use messageId and correlId.
http://www.mqseries.net/phpBB2/viewtopic.php?t=7298&highlight=paradigm
This is from the java manualFor an MQQueue.put() call, this specifies the message identifier to use. If
MQC.MQMI_NONE is specified, the queue manager generates a unique
message identifier when the message is put. The value of this member
variable is updated after the put to indicate the message identifier that was
used.
So even if you use inMsg.messageId = MQC.MQCI_NONE, the unique messageId that was generated by MQ can be retrieved after you make the PUT.
In your earlier post you have posted only one side of the application. You haven't posted the other application code, so, it's hard to tell.
In the other (receiving) application what you have to do is grab the incoming message's messageId and put that in the correlId of the outgoing message
In your fisrt program even if you uncomment this line
gmo.matchOptions = MQC.MQMO_MATCH_CORREL_ID;
I think it will work.
Hope atleast this will make things clearer
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Venny
Last edited by vennela on Wed Feb 12, 2003 10:39 am; edited 1 time in total |
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| Praveen |
| Posted: Wed Feb 12, 2003 10:20 am Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Venny,
Other application sends back the message with messageID the same as the messagesID for the message they receive from our application. For CorrelationID, they set it to NONE when send back any message to our application. In this case I need to recieve the messages by checking the proper messsageId instead correlationId,right?. So can I do like this?
While putting the message
inMsg.messageId = MQC.MQCI_NONE
And while getting it back.
outMsg.messageId = MQC.MQMO_MATCH_MSG_ID;
I am not sure whether this is right or wrong?, please tell me how to check it.
_________________
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Praveen K |
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| bduncan |
| Posted: Wed Feb 12, 2003 10:36 am Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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When you create the request message, set the MsgId field in the MQMD to MQCI_NONE . Then, in your MQPMO structure, set the MQPMO_NEW_MSG_ID parameter. Set the CorrelId in the MQMD to MQCI_NONE.
Now, when the processing application gets the request message, processes it, and creates the reply message, you need to do the following. Set the MsgId field in the MQMD to MQCI_NONE. In your MQPMO structure, set the MQPMO_NEW_MSG_ID parameter. Finally, set the CorrelId in the MQMD to the MsgId of the request message.
Now, the application looking for the reply message should be using the match option MQMO_MATCH_CORREL_ID, and set the CorrelId in the MQMD that you pass to the MQGET call to value of the MsgId that was set in the MQMD of the request message after you made your MQPUT.
The thing wrong with your scheme is that your reply message ends up having the same MsgId as the request message. This is wrong, because MsgId is supposed to be a unique identifier - no to messages should have the same value. It is more appropriate to use the CorrelId to retrieve the specific reply message. So to illustrate, if your application put a request message, it might look like:
REQUEST MESSAGE
MsgId: 555555
CorrelId:
REPLY MESSAGE
MsgId: 754321
CorrelId: 555555
And the application which made the original request will be looking for a reply message with a CorrelId matching the MsgId of the request message, or 555555.
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Brandon Duncan
IBM Certified MQSeries Specialist
MQSeries.net forum moderator |
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| vennela |
| Posted: Wed Feb 12, 2003 10:50 am Post subject: |
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Jedi Knight
Joined: 11 Aug 2002
Posts: 4055
Location: Hyderabad, India
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| bduncan |
| Posted: Wed Feb 12, 2003 11:25 am Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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Funny, I thought I was typing something I'd already typed before 
Thanks for jogging my memory Venny... Hopefully I'll use the search button before I spend another 15 minutes typing away...
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| Praveen |
| Posted: Wed Feb 12, 2003 12:56 pm Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Brandon,
This is how I have to do right?, please correct me if I am wrong.
| Code: |
MQMessage inMsg = new MQMessage();
inMsg.messageId = MQC.MQCI_NONE;
inMsg.correlationId = MQC.MQCI_NONE;
MQPutMessageOptions pmo = new MQPutMessageOptions();
pmo.options = MQC.MQPMO_NEW_MSG_ID;
MQGetMessageOptions gmo = new MQGetMessageOptions();
gmo.matchOptions = MQC.MQMO_MATCH_CORREL_ID; |
Other application sends back the message with messageID the same as the messagesID for the message they receive from our application. For CorrelationID, they set it to NONE when send back any message to our application. They cannot change their code now. I have to make my code to work for this. Will the above solution work for this kind of response from the other application?, if not what is the alternative I need to use?.
Thanks for your response.
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Praveen K |
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| bduncan |
| Posted: Wed Feb 12, 2003 2:48 pm Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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Well I suppose if you can't change the other application then we're stuck using the MsgId. So I would say that your code looks correct, except that you need to load the MsgId value you wish to match against into the MsgId field of the MQMessage object that you are passing into the MQGET call. I think this is what you are missing...
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Brandon Duncan
IBM Certified MQSeries Specialist
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| Praveen |
| Posted: Thu Feb 13, 2003 6:27 am Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Brandon,
So now my code should look like this
Before putting the message
| Code: |
inMsg.messageId = MQC.MQCI_NONE;
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While getting it
| Code: |
gmo.matchOptions = MQC.MQMO_MATCH_MSG_ID
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is it right?.
_________________
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Praveen K |
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| bduncan |
| Posted: Thu Feb 13, 2003 10:50 am Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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Right, but as I said, in addition to what you already have, you must tell the queue manager which MsgId to match against. If you simply do an MQGET and say MQC.MQMO_MATCH_MSG_ID, the queue manager has no idea which MsgId you wish to match against. When the MQGET is successful, you end up with a message object right? Well, when you pass this object to your MQGET call, you must populate the MsgId field with the MsgId that you are looking to match against.
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Brandon Duncan
IBM Certified MQSeries Specialist
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| Praveen |
| Posted: Thu Feb 13, 2003 11:38 am Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Brandon,
Can you please send me a piece of code how to do that. Sorry for the trouble.
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Praveen K |
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| Praveen |
| Posted: Fri Feb 14, 2003 4:20 am Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Brandon/Venny,
Can you please send me the code, I mean to how to set the msgId while putting and getting the messages?
_________________
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Praveen K |
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| bduncan |
| Posted: Fri Feb 14, 2003 10:19 am Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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Praveen,
I'm sorry but I don't have the exact code you are seeking (and really don't have the time to sit down and write it right now - sorry) I would recommend looking at the Java samples in the software repository. You will probably find something that shows how to do an MQGET while matching against something...
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Brandon Duncan
IBM Certified MQSeries Specialist
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| vennela |
| Posted: Fri Feb 14, 2003 11:39 am Post subject: |
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Jedi Knight
Joined: 11 Aug 2002
Posts: 4055
Location: Hyderabad, India
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Praveen:
I have written a small program that would PUT to a queue QUEUE1 and get from the same Queue by matching the message Id. Hope this will help you in building your application:
| Code: |
import com.ibm.mq.*;
public class SendAndReceive extends Object {
public SendAndReceive() {
}
/**
* @param args the command line arguments
*/
public static void main (String args[]) {
try {
String QM1 = "FMCQM";
String QUEUE1 = "HELLOWORLD";
System.out.println("Starting SendAndReceive Program: ");
MQQueueManager qmgr = new MQQueueManager(QM1 ) ;
System.out.println("Connected to QMGR " + QM1);
int openOptions = MQC.MQOO_OUTPUT | MQC.MQOO_FAIL_IF_QUIESCING | MQC.MQOO_SET_IDENTITY_CONTEXT;
MQQueue InQueue = qmgr.accessQueue(QUEUE1 , openOptions, null, null, null);
MQMD messageDesc = new MQMD();
messageDesc.replyToQueueName = "HELLOWORLD";
messageDesc.replyToQueueManagerName = "WMTQM";
messageDesc.userId = "ADMIN";
MQMessage inMessage = new MQMessage();
inMessage.writeString("What is your name");
InQueue.put(inMessage);
System.out.println("Message Id is :" + inMessage.messageId);
InQueue.close();
int openOptionsForGet = MQC.MQOO_INPUT_SHARED ;
MQQueue OutQueue = qmgr.accessQueue(QUEUE1 , openOptionsForGet, null, null, null);
MQGetMessageOptions gmo = new MQGetMessageOptions() ;
MQMessage outMessage = new MQMessage();
outMessage.messageId = inMessage.messageId;
gmo.matchOptions = MQC.MQMO_MATCH_MSG_ID;
OutQueue.get(outMessage, gmo);
String msgTxt = outMessage.readString(outMessage.getMessageLength());
System.out.println (" The message is \n" + msgTxt);
OutQueue.close();
qmgr.disconnect() ;
}
catch(MQException ex){
System.out.println("MQ Error - Reason code :" + ex.reasonCode);
}
catch (Exception e){
System.out.println("Error : " + e);
}
}
} |
Notice the following three lines of code:
MQMessage outMessage = new MQMessage();
outMessage.messageId = inMessage.messageId;
gmo.matchOptions = MQC.MQMO_MATCH_MSG_ID;
OutQueue.get(outMessage, gmo);
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Venny |
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| Praveen |
| Posted: Mon Feb 17, 2003 5:12 am Post subject: |
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Apprentice
Joined: 23 Oct 2002
Posts: 40
Location: Bangalore
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Venny,
Thank you very much for the code.
In the multiple user session enviroment this code should work fine right?, I mean if one user sends a request to server then he will get the response for his input only and other users for their inputs, right?.(that is what I want basically).
One more thing, will it slow down the process?, because after adding this i,e checking with the proper msgIds I am getting the reply very late.
_________________
Thanks,
Praveen K |
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