Timeout specifications on input messages

Each and every input message from the IMS Connect client can set a different timeout value in the IRM_TIMER field of the fixed portion of the IMS request message (IRM) header.

Set the IRM_TIMER value to an appropriate wait time for IMS to return data to IMS Connect.

The settings for the IRM_TIMER is enforced as described in the following list:

1. If the IRM_TIMER is set at X'00', the following default values are used:
   • The default for all RESUME_TPIPE is two seconds.
   • The default for all RESUME_TPIPE non-single ACK is .25 seconds.
   • The value of the TIMEOUT parameter in the IMS Connect TCPIP configuration statement for all others.
2. X'FF' and X'01' - X'9E' are used only when requested.
3. X'E9' (char Z) NO_WAIT means do not wait for any IMS output. NO_WAIT is not valid on some Client SENDs. Because IMS Connect does not wait for output from IMS, on a transaction socket connection, IMS Connect disconnects the socket; and on a persistent socket connection, IMS Connect requests the next input from the client rather than disconnect the socket. If NO_WAIT is used, it is enforced as follows:
   • There is a two second delay for:
     • RESUME_TPIPE request
     • conversational transaction code
     • conversational data
     • ACK or NAK associated with a conversational transaction
     • non-conversational transaction code
   • A .25 second delay for each of the following is used:
     • an ACK or NAK associated with a non-conversational transaction commit mode one confirm
     • an ACK or NAK associated with a RESUME_TPIPE with Asynch output options AUTO or NOAUTO
     • an ACK or NAK associated with non-conversational transaction commit mode zero confirm
   • NO_WAIT can be used for the following:
     • a SENDONLY
     • an ACK or NAK associated with RESUME_TPIPE with Asynch output option SINGLE
     • an ACK or NAK associated with non-conversational transaction commit mode zero confirm with the IRM NOWAIT flag

Misuse of X'E9' can result in one of the following problems:

1. The socket disconnects.
2. An output message to the client on a transaction socket is lost.
3. A hang condition occurs between the client and IMS Connect or IMS Connect and OTMA. For example, the client can be in a READ state waiting for output from IMS Connect while IMS Connect is in a READ state waiting for input from the client and OTMA is in READ state waiting for acknowledgment.
4. The deallocate commit or deallocate abort notification for CM1 SynchLevel=Confirm is lost.
5. Other unpredictable conditions occur.

To determine the appropriate wait time for IMS to return data to IMS Connect, consider the following guidelines:

• For a client SEND of transaction code and data or data only, the IRM_TIMER value should be set to reflect the amount of time IMS Connect should wait for the output from IMS.
  Recommendation: Do not use a timer value of X'E9' except for messages with the NOWAIT flag set on the IRM.
• If the client application knows that the last message received is the last output message to the client for the transaction, set the IRM_TIMER to X'01' (.01 of a second) for a client SEND of ACK or NAK. The IRM_TIMER of X'01' is the smallest value that can be set for non-RESUME TPIPE ACK messages. However, if the ACK message is associated with an output from a RESUME TPIPE call, do not set the IRM_TIMER value to X'E9' (character Z).
• For a client SEND of a RESUME TPIPE call, the timer value can be set as follows:

  AUTO option

  X'FF' for dedicated output device, or any X'00' to X'9E' values for non-dedicated output device

  NOAUTO option

  any value other than X'FF' or X'E9'

  SINGLE or SINGLE with WAIT option

  any value other than X'FF' or X'E9'