Use of the message descriptor in the MQAI

The message descriptor that the MQAI generates is set to an initial value when the data bag is created.

The PCF command type is obtained from the system item with selector MQIASY_TYPE. When you create your data bag, the initial value of this item is set depending on the type of bag you create:

Type of bag	Initial value of MQIASY_TYPE item
MQCBO_ADMIN_BAG	MQCFT_COMMAND
MQCBO_COMMAND_BAG	MQCFT_COMMAND
MQCBO_*	MQCFT_USER

When the MQAI generates a message descriptor, the values used in the Format and MsgType parameters depend on the value of the system item with selector MQIASY_TYPE as shown in Table 1.

PCF command type	Format	MsgType
MQCFT_COMMAND	MQFMT_ADMIN	MQMT_REQUEST
MQCFT_REPORT	MQFMT_ADMIN	MQMT_REPORT
MQCFT_RESPONSE	MQFMT_ADMIN	MQMT_REPLY
MQCFT_TRACE_ROUTE	MQFMT_ADMIN	MQMT_DATAGRAM
MQCFT_EVENT	MQFMT_EVENT	MQMT_DATAGRAM
MQCFT_*	MQFMT_PCF	MQMT_DATAGRAM

Table 2 shows that if you create an administration bag or a command bag, the Format of the message descriptor is MQFMT_ADMIN and the MsgType is MQMT_REQUEST. This is suitable for a PCF request message sent to the command server when a response is expected back. Other parameters in the message descriptor take the values shown in Table 3.

Parameter	Value
StrucId	MQMD_STRUC_ID
Version	MQMD_VERSION_1
Report	MQRO_NONE
MsgType	see Table 2
Expiry	30 seconds (note 1 )
Feedback	MQFB_NONE
Encoding	MQENC_NATIVE
CodedCharSetId	depends on the bag CCSID (note 2 )
Format	see Table 2
Priority	MQPRI_PRIORITY_AS_Q_DEF
Persistence	MQPER_NOT_PERSISTENT
MsgId	MQMI_NONE
CorrelId	MQCI_NONE
BackoutCount	0
ReplyToQ	see note 3
ReplyToQMgr	blank

Notes:

1. This value can be overridden on the mqExecute call by using the OptionsBag parameter. For information about this, see mqExecute.
2. See Data conversion processing in the MQAI.
3. Name of the user-specified reply queue or MQAI-generated temporary dynamic queue for messages of type MQMT_REQUEST. Blank otherwise.

Parent topic: Advanced MQAI topics