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| help on UOW |
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| adder |
 Posted: Wed Mar 01, 2006 6:25 pm Post subject: help on UOW |
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Apprentice
Joined: 06 Dec 2005
Posts: 43
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I write a sample code(c++) to learn UOW of MQ, in this sample
syncpoint does not used, I choose qmgr.begin() and qmgr.commit()
first put a message and call qmgr.commit()
second put a message and call qmgr.backout()
but these two message all put into queue when I use amqsget to check.
So I wanna know what's wrong, thanks!
| Code: |
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <imqi.hpp>
const int MAX_BUFF_SIZE = 100;
using namespace std;
int main(int argc, char **argv) {
ImqQueueManager qmgr;
ImqQueue queue;
ImqMessage msg;
ImqPutMessageOptions pmo;
int bSyncPoint = 0; /* indicator if messages are in syncpoint */
MQLONG buflen; /* buffer length */
char buffer[MAX_BUFF_SIZE];
cout << "Sample mqsync C++ start" << endl;
if (argc < 2) {
cout << "Required parameter missing - queue name" << endl;
exit(99);
}
/***************************************************************/
/* Connect to queue manager */
/***************************************************************/
if (argc > 2) {
qmgr.setName( argv[ 2 ] );
}
if ( !qmgr.connect( ) ) {
cout << "ImqQueueManager::connect failed with reason code "
<< qmgr.reasonCode( ) << endl;
exit(99);
}
/***************************************************************/
/* Get the queue name that will be used and open it for output */
/***************************************************************/
queue.setConnectionReference( qmgr );
queue.setName( argv[ 1 ] );
queue.setOpenOptions( MQOO_OUTPUT | MQOO_INQUIRE );
queue.open();
/***************************************************************/
/* If there was an error opening the queue, print it out. */
/***************************************************************/
if (queue.reasonCode()) {
cout << "ImqQueue::open ended with reason code "
<< queue.reasonCode( ) << endl;
}
if (queue.completionCode()) {
cout << "Unable to open queue for output" << endl;
}
msg.useEmptyBuffer(buffer, sizeof(buffer));
msg.setFormat(MQFMT_STRING);
strcpy(buffer,"commit message");
msg.setMessageLength(strlen(buffer));
qmgr.begin();
if (!queue.put(msg, pmo))
cout << "ImqQueue::put ended with reason code "
<< queue.reasonCode( ) << endl;
qmgr.commit();
memset(buffer,0,sizeof(buffer));
strcpy(buffer,"backout message");
msg.setMessageLength(strlen(buffer));
qmgr.begin();
if (!queue.put(msg, pmo))
cout << "ImqQueue::put ended with reason code "
<< queue.reasonCode( ) << endl;
qmgr.backout();
if ( !queue.close()) {
cout << "ImqQueue::close ended with reason code "
<< queue.reasonCode( ) << endl;
}
if (!qmgr.disconnect()) {
cout << "ImqQueueManager::disconnect ended with reason code "
<< qmgr.reasonCode( ) << endl;
}
cout << "Sample mqsync C++ end" << endl;
return(0);
} |
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| wschutz |
| Posted: Wed Mar 01, 2006 6:30 pm Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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you need to specify MQPMO_SYNCPOINT when putting the messages, otherwise they are committed as soon as the put is called.
_________________
-wayne
Last edited by wschutz on Wed Mar 01, 2006 6:38 pm; edited 1 time in total |
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| mvic |
| Posted: Wed Mar 01, 2006 6:36 pm Post subject: Re: help on UOW |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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Wayne is quite right.
Also, you did not check the success of qmgr.begin(). In this scenario I think it will not succeed (qmgr.begin is MQBEGIN, which begins a distributed unit of work incorporating database updates - but I am guessing you don't have the necessary config for this in qm.ini).
Seeing that you are not performing any database updates, you probably aren't interested in using distributed units of work, and so qmgr.begin() is not relevant for this app anyway. |
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| mvic |
| Posted: Wed Mar 01, 2006 6:41 pm Post subject: Re: help on UOW |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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Also it is very important to check the success of qmgr.commit(). UOWs can fail for a variety of reasons (most often if the system is in some difficulty - eg. getting short of disk space to log the transaction). Although this is rare, the integrity of your UOW is obviously important, so you must code to handle the failing commit. |
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| adder |
| Posted: Wed Mar 01, 2006 7:02 pm Post subject: |
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Apprentice
Joined: 06 Dec 2005
Posts: 43
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mvic,wschutz, thanks very much.
I am a fresh man for MQ. so for every message put into or get from MQ, syncpoint option need to be set in pmo or gmo, then these message can be in a UOW, right?
| Code: |
| pmo.setSyncPointParticipation(TRUE); |
and check stauts of commit
| Code: |
if (!qmgr.commit()) {
cout << "ImqQueueManager::commit ended with reason code "
<< qmgr.reasonCode( ) << endl; |
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| wschutz |
| Posted: Wed Mar 01, 2006 7:06 pm Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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| Quote: |
so for every message put into or get from MQ, syncpoint option need to be set in pmo or gmo, then these message can be in a UOW, right?
|
Yes, on windows,iSeries and unix qmgrs, the default is that the put or get of a message is immediately committed, so if you want the put/get to be part of a larger unit of work, you must specify gmp/pmo_syncpoint.
(by the way, the default on zOS is the opposite  )
_________________
-wayne |
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| adder |
| Posted: Wed Mar 01, 2006 7:33 pm Post subject: |
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Apprentice
Joined: 06 Dec 2005
Posts: 43
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another question:
can MQ support more than one queue manager involoved into one UOW? |
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