ATTRDPN and ATTRPRN
The return destination process name (ATTRDPN) and return primary resource name (ATTRPRN) parameters define the reply process and the return primary resource within the source session and should be returned to the source session on resulting replies to facilitate return-reply routing within the source session.
If provided on input to IMS and not changed or deleted by an output MFS format description, these parameters are returned to the source session unmodified in the reply ATTACH FM header as the output ATTACH ATTDPN and ATTPRN parameters respectively. These parameters are associated with the message to be processed and are recovered with the message across session and subsystem failures.
The input ATTRDPN and ATTRPRN are not automatically retained from one input or output message to another. The ATTRDPN and ATTRPRN must be explicitly provided with each input message or through the MFS output format descriptors when MFS DPM is used for output. The ATTRDPN results from MFS if a next MID was specified in the MOD.
A different procedure is followed when the reply is to be returned on a session different from the session on which the input message originated. If the output ATTRPRN is not set by MFS, and the source of the output message is not associated with the same session, IMS does not wrap the input ATTRDPN and ATTRPRN as the output ATTDPN and ATTPRN respectively. In this case, IMS also automatically inserts the source LTERM name of the terminal entering the input message switch or transaction (for alternate PCB output) as the output ATTRPRN parameter.
When the ATTRDPN parameter is not available for output, a 1-byte length field containing X'00' is included in the output ATTACH FM header.
The following tables summarize IMS actions relative to the DPN, PRN, RDPN, and RPRN fields in the ATTACH and SCHEDULER headers sent with the message.
| Input FMH | IMS interpretation |
|---|---|
| DPN | MFS MID name or input message editor name (ISC edit or basic edit). Defaults to ISCEDT if not supplied. |
| PRN | Input transaction code or LTERM name, overriding data stream and preset mode except during conversation. |
| RDPN | Saved as default reply DPN field. |
| RPRN | Saved as default reply PRN field. |
| Output FMH field | IMS ACTION reply message sent on same session as input | IMS ACTION reply message or asynchronous output sent on another session |
|---|---|---|
| ATTDPN | Wrapped input ATTRDPN
if provided; optionally overridden by MFS. For ATTACH-only output, if no parameter is available, the DPN is not sent. For SCHEDULER output, the default is ISCEDT. |
Provided only using MFS. For ATTACH-only output, if no parameter is available, the DPN is not sent. For SCHEDULER output, the default is ISCEDT. |
| ATTPRN | Wrapped input ATTRPRN; optionally overridden by MFS | Provided only using MFS |
| ATTRDPN | Provided only using MFS | Provided only using MFS |
| ATTRPRN | Provided only using MFS | Automatically defaulted to source LTERM name; optionally overridden by MFS |