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MQ: You want to put a message into a queue and you want to generate duplicate messages into other queues

Question & Answer


Question

Scenarios that are addressed in this technote:
1) You are using point-to-point (queues) with your putting and getting applications. You want to use  MQ  Pub/Sub under the covers and you do not want your putting and getting applications to be aware of Pub/Sub. That is, the application that puts messages into a queue continues to put messages into a queue, and the getting applications keep getting messages from a queue.
2) You are using point-to-point and you want to create "duplicate" messages that will be stored in queues Q1 and Q2, when the message is put into the queue "DESTINATION"

Answer

This example uses the concepts of "topic objects" and "topic alias" introduced in MQ V7.
With the setup described below, you can put a message into a queue and a copy of the message will be placed on queues Q1 and Q2.
 
You can use the MQ Explorer or the amqsput sample to put a message to the DESTINATION queue, which is an alias for a topic and thus, a message is really published into the topic T1 and this causes the subscribers SUB1 and SUB2 to receive the messages (which are stored in queues Q1 and Q2 respectively).
Or you could also publish directly into topic T1, and the messages will be received in Q1 and Q2.

Use runmqsc to define the following objects:

define ql(Q1)
define ql(Q2)
define qalias(DESTINATION) target(T1) targtype(topic)
define topic(T1) topicstr('TOPIC1') usedlq(NO)
define sub(SUB1) topicstr('TOPIC1') dest(Q1)
define sub(SUB2) topicstr('TOPIC1') dest(Q2)
Note (Thanks to Tim Zielke for his feedback):
The reason for the non-default "usedlq(NO)" in the statement "define topic" is that most MQ administrators would not want this duplicated message set up to spill onto the DLQ if a queue becomes full.

++ Example of running amqsput and amqsget:

a) Open 3 windows:
window 1: get messages from queue Q1
amqsget Q1 QMGR

window 2: get messages from queue Q2
amqsget Q2 QMGR

window 3: put a message into the queue DESTINATION
amqsput DESTINATION QMGR
Sample AMQSPUT0 start
target queue is DESTINATION
TEST
Sample AMQSPUT0 end

b) Observe that Q1 and Q2 receive the same message:

amqsget Q1 QMGR
Sample AMQSGET0 start
message <TEST>
no more messages
Sample AMQSGET0 end

amqsget Q2 QMGR
Sample AMQSGET0 start
message <TEST>
no more messages
Sample AMQSGET0 end

c) NOTE: Strictly speaking, the messages received by Q1 and Q2 are NOT truly identical. Even though they will have the same payload (text string 'TEST') and same characteristics, each message will have its own unique message-id.

The following is a browse (using: amqsbcg Queue QMGR) of the messages.

Notice that the only differences in this particular example are the last 2 characters from "MsgId" and CorrelId". In your case, more characters in this field could be different.

Message received by Q1:
  MsgId :    X'414D5120514D5F3730312020202020207064DF4E20003603'
                                                             **
  CorrelId : X'414D5120514D5F3730312020202020207064DF4E20001E08'
                                                             **

Message received by Q2:
  MsgId :    X'414D5120514D5F3730312020202020207064DF4E20003602'
                                                             **
  CorrelId : X'414D5120514D5F3730312020202020207064DF4E20001E0E'
                                                             **

c.1) Message received by Q1

****Message descriptor****

StrucId : 'MD ' Version : 2
Report : 0 MsgType : 8
Expiry : -1 Feedback : 0
Encoding : 546 CodedCharSetId : 437
Format : 'MQSTR '
Priority : 0 Persistence : 0
MsgId : X'414D5120514D5F3730312020202020207064DF4E20003603'
CorrelId : X'414D5120514D5F3730312020202020207064DF4E20001E08'
BackoutCount : 0
ReplyToQ : ' '
ReplyToQMgr : 'QMGR '
** Identity Context
UserIdentifier : 'rivera '
AccountingToken :
X'16010515000000BA1E06D2603C3514885EDBC2EF03000000000000000000000B'
ApplIdentityData : ' '
** Origin Context
PutApplType : '26'
PutApplName : 'QMGR '
PutDate : '20111207' PutTime : '20215396'
ApplOriginData : ' '

GroupId : X'000000000000000000000000000000000000000000000000'
MsgSeqNumber : '1'
Offset : '0'
MsgFlags : '0'
OriginalLength : '-1'

**** Message ****

length - 4 bytes

00000000: 5445 5354 'TEST '

c.2) Message received by Q2

****Message descriptor****

StrucId : 'MD ' Version : 2
Report : 0 MsgType : 8
Expiry : -1 Feedback : 0
Encoding : 546 CodedCharSetId : 437
Format : 'MQSTR '
Priority : 0 Persistence : 0
MsgId : X'414D5120514D5F3730312020202020207064DF4E20003602'
CorrelId : X'414D5120514D5F3730312020202020207064DF4E20001E0E'
BackoutCount : 0
ReplyToQ : ' '
ReplyToQMgr : 'QMGR '
** Identity Context
UserIdentifier : 'rivera '
AccountingToken :
X'16010515000000BA1E06D2603C3514885EDBC2EF03000000000000000000000B'
ApplIdentityData : ' '
** Origin Context
PutApplType : '26'
PutApplName : 'QMGR '
PutDate : '20111207' PutTime : '20215396'
ApplOriginData : ' '

GroupId : X'000000000000000000000000000000000000000000000000'
MsgSeqNumber : '1'
Offset : '0'
MsgFlags : '0'
OriginalLength : '-1'

**** Message ****

length - 4 bytes

00000000: 5445 5354 'TEST '
+++ end +++

[{"Line of Business":{"code":"LOB15","label":"Integration"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"ARM Category":[{"code":"a8m0z00000008ObAAI","label":"Components and Features->Administration"}],"ARM Case Number":"","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All Version(s)"}]

Product Synonym

WMQ MQ MQSeries

Document Information

Modified date:
23 February 2021

UID

swg21574670