Send-then-commit flow with confirm

The send-then-commit flow assumes no synchronization for the transactions as they are processed by IMS.

This topic shows a flow in which all transactions are confirmed as they are received (each message requests a response). The sample illustrated in the figure below assumes the following:
  • Commit Mode 1 is specified in the state-data section of the message prefix.
  • The transaction pipe is not synchronized.
  • The Synchronization Level is specified as Confirm in the state-data section.

If NAK is received by IMS, then a user 119ABEND occurs in the application and IMS issues a DFS554 message to the client.

Following the figure below is a sequential list that provides more details on the flow.

Figure 1. Send-then-commit with confirm flow
Client is on the left; IMS TM is in the middle, application is to the right. Arrows are shown that reflect sequence of flow.

The sequence of flow shown in the above figure is:

  1. Transaction initiated
  2. Transaction inserted to SMB
  3. GU call followed by ISRT to IOPCB
  4. Sync point start
  5. Output sent; response requested
  6. ACK
  7. DB is committed; commit is confirmed; IMS completed sync point
  8. Transaction completed