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| sfari |
 Posted: Mon Apr 25, 2005 8:54 am Post subject: Get and Put again with same MessageID |
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Centurion
Joined: 15 Apr 2003
Posts: 144
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Hi,
Is it somehow possible to get a Message from a Queue manipulate the data and put it again on the same Queue
without having a changed MessageID afterwards? I need to use JMS because there are JMS Properties and Data which have to updated.
Clients are looking for Messages with specific Message IDs. So it is important that after my update the message is still available under the same ID.
Are there may some static MQ settings which influence the generation of Message IDs?
I am happy about any hint! Thanks! |
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| jefflowrey |
| Posted: Mon Apr 25, 2005 9:06 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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You can't preserve the message ID if you use JMS to send the message.
The JMS send always changes the message ID.
You should be able to write code that will copy the message, JMS header and all, to an MQ message that can be put using the Java API for WebSphere MQ.
_________________
I am *not* the model of the modern major general. |
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| fjb_saper |
| Posted: Mon Apr 25, 2005 4:15 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| jefflowry wrote: |
| You can't preserve the message ID if you use JMS to send the message |
I know this to be true when you create the message via JMS. I am not so sure about it if you just move the message from one queue to the other.
You may have no choice as you may have to modify the payload.
Try something simple. Create a message and put on queue A. Get the JMSMessageID and store it in memory and print it out. Consume the message. Create a new message and set the JMSMessageID to the one in memory. Post the message to a queue.
Check the message id. If nothing else it is worth a try
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| EddieA |
| Posted: Mon Apr 25, 2005 4:57 pm Post subject: |
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Jedi
Joined: 28 Jun 2001
Posts: 2453
Location: Los Angeles
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| Quote: |
| I am not so sure about it if you just move the message from one queue to the other |
| Quote: |
| The JMS send always changes the message ID |
From the Java Manual:
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setJMSMessageID
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Any value set using this method is ignored when the message is sent, but this method can be used to change the value in a received message. |
Cheers,
_________________
Eddie Atherton
IBM Certified Solution Developer - WebSphere Message Broker V6.1
IBM Certified Solution Developer - WebSphere Message Broker V7.0 |
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| clindsey |
| Posted: Tue Apr 26, 2005 4:50 am Post subject: |
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Knight
Joined: 12 Jul 2002
Posts: 586
Location: Dallas, Tx
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Were you planning to return the message to the same queue. If so, how can you be sure your code to modify the content would get the message before your client's app. Seems you would have to insert a staging queue in the mix to receive the messages first, where you could modify and redirect them.
To intercept the message on the destination queue and modify it before the receiving app, you would have to use an API Exit.
Charlie |
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| jefflowrey |
| Posted: Tue Apr 26, 2005 5:03 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| clindsey wrote: |
| To intercept the message on the destination queue and modify it before the receiving app, you would have to use an API Exit. |
Which you can't write in Java. Not even in v6.
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I am *not* the model of the modern major general. |
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| sfari |
| Posted: Tue Apr 26, 2005 5:19 am Post subject: |
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Centurion
Joined: 15 Apr 2003
Posts: 144
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I am able to do the message manipulation during a maintainance window so I am sure the application does not consume the messages at the same time.
I think I found a way to do what I want but I am not very happy with it! It's not very elegant  and I am not really sure if it really works.
1. get the message using JMS
2. save the message id
3. manipulate the message
4. put the manipulated message backto the queue (new msgid will be issued)
5. get this message again with MQ base API
6. change the message id to the saved one in step 2
7. put the message back to the queue
With MQ base Java classes it is possible to manipulate a message id manually. A problem is that between step 4 and 5 I need to convert the message ID from a string to a byte array, since JMS does return the ID as string. I don't know what kind of conversion IBM is using for that.
Silvano |
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| jefflowrey |
| Posted: Tue Apr 26, 2005 5:33 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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You should be able to skip writing it to a queue and then getting it again.
Set your properties, extract the bytes of the JMS message and then create a new MQ Message and set the MQMD fields.
_________________
I am *not* the model of the modern major general. |
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| sfari |
| Posted: Tue Apr 26, 2005 5:51 am Post subject: |
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Centurion
Joined: 15 Apr 2003
Posts: 144
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If I do it that way I need to rebild the whole MQRFH2 2 Header with its XML property structure. Is it not much more complicated to do this correctly than to just put it with JMS and get it again with MQ base?
The only problem I see with this solution is as I said the convertion of the string msgId (JMS) to a byte msgId (MQ base).
Thanks
Silvano |
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| fjb_saper |
| Posted: Tue Apr 26, 2005 5:30 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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This conversion should pose no problem. Look at the different methods.
One of them should be byte[] getJMSMessageIDasBytes()
Enjoy  |
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| sfari |
| Posted: Wed Apr 27, 2005 1:28 am Post subject: |
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Centurion
Joined: 15 Apr 2003
Posts: 144
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I haven't found such a method  . As far as I have seen the Message ID in JMS is always represented as String. Thus in a mix of the JMS and MQ base I would need to know how to convert this String to a byte[]. |
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| clindsey |
| Posted: Wed Apr 27, 2005 6:11 am Post subject: |
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Knight
Joined: 12 Jul 2002
Posts: 586
Location: Dallas, Tx
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There is method getJMSCorrellationIDAsBytes but no getJMSMessageIDAsBytes.
I believe getJMSMessageID.getBytes() will use the String getBytes method to return a byte array.
Charlie |
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