Serialization of input between separate integration servers running on the same integration node on z/OS

This example demonstrates that only one MQInput node at a time is allowed to take messages from a shared queue when the same serialization token is used by message flows running in separate integration servers on the same integration node.

An identical message flow MyFlowA is deployed to two integration servers called MYIntServerA and MYIntServerB on integration node integrationNodeName.

In this case, the queue manager does not need to participate in a queue sharing group. The input queue INQueue is defined as local with disposition QMGR.

The message flows do not have to be identical; the significant point is that an identical serialization token is used in both flows.

The simple message flow in this example consists of an MQInput node connected to an MQOutput node. The MQInput node in both message flows gets messages from the shared queue INQueue.QSG; the node attribute Serialization Token is configured as MyToken123ABC in both MQInput nodes.

The message flow property additional Instances takes the default value of zero in both message flows, which ensures that input is serialized within the flow.

Illustration showing multiple integration servers in the same integration node

Here is a typical sequence of events for this example.

Integration node integrationNodeName starts and the first message flow to begin is MyFlowA in integration server MyIntServerA. The MQInput node MyInputNode connects to queue manager MQ01 using the serialization token MyToken123ABC. The MQInput node successfully opens shared queue INQueue and gets input messages.
The second integration server MyIntServerB starts and message flow MyFlowA in integration server MyIntServerB begins. The MQInput node MyInputNode now attempts to connect to queue manager MQ01 using serialization token MyToken123ABC. The following SDSF console message is logged:
```
 BIP2656I integrationNodeName MyIntServerB 11 UNABLE TO OPEN QUEUE
 'INQueue' ON IBM INTEGRATION BUS QUEUE 
 MANAGER 'MQ01':  BECAUSE SERIALIZATION TOKEN  
 MyToken123ABC is already in use. NO USER ACTION REQUIRED
```
Message flow MyFlowA in integration server MyIntServerB is unable to process input because the serialization token it has passed is already in use within the queue manager (by the MQInput node in message flow MyFlowA in integration server MyIntServerA). This is indicated by the reason code 2271 (MQRC_CONN_TAG_IN_USE) in message bip2623.
The first integration server is deleted or canceled.
If the first integration server is canceled by the operator, ends with an abend, or is deleted during a redeployment of the integration node configuration, the input node in the second integration server is now able to get input messages from queue INQueue.
A sequence of SDSF console messages is logged, of which the following one is relevant:
```
  BIP2091I integrationNodeName MyIntServerB 11 THE INTEGRATION NODE HAS 
 RECONNECTED TO IBM INTEGRATION BUS 
 SUCCESSFULLY : ImbCommonInputNode(785)               
```

Message flow MyFlowA in integration server MyIntServerB is now able to recover processing of messages from the shared queue INQueue.QSG.

Note that, although serialization of input can be achieved in a similar manner by configuring the input queue for exclusive input, this does not ensure message integrity during a recovery situation. This can be achieved only through the use of the serialization token as described in this example.