Websphere MQ configuration details
For message header access, Websphere MQ adds a message descriptor,
MQXQH
structure. This contains control information for each message
before placing the message into a transmission queue. The MQXQH
structure has five fields, the last of which is MsgDesc. The MsgDesc parameter is
another structure (MQMD
). It is the MQMD
, MQ Message
Descriptor, information that remains with the message after it arrives at its
destination queue.
MQMD
values, the COPY MQMD
switch must be set for
the inbound queue. Do this by selecting on the MQ Inqueue Advanced
Properties dialog box. The MQMD
structure has fields which are accessible to
users. Ten of these fields are most often user-modified:
MSGTYPE
: Message type.EXPIRY
: Message lifetime.FORMAT
: Format name.PRIORITY
: Message priority.PERSISTENCE
: Message persistence.MSGID
: Message identifier.CORRELID
: Correlation identifier.REPLYTOQ
: Name of reply queue.REPLYTOQMGR
: Name of reply Queue Manager.REPORT
: Options for report messages.
The message and correlation identifiers are particularly important for matching messages with replies, which are found in physically different locations. Messages are generally put into a remote queue for sending to a remote server. The reply from the remote server is found in a separate local queue established to receive replies only.
The remainder of the MQMD
fields are:
STRUCID
: Structure identifier.VERSION
: Structure version number.FEEDBACK
: Feedback or reason code.ENCODING
: Data encoding.CODEDCHARSETID
: Coded character set identifier.BACKOUTCOUNT
: Backout counter.USERIDENTIFIER
: User identifier.ACCOUNTINGTOKEN
: Accounting token.APPLIDENTITYDATA
: Application data relating to identity.PUTAPPLTYPE
: Type of application that Put the message.PUTAPPLNAME
: Name of application that Put the message.PUTDATE
: Date when message was Put.PUTTIME
: Time when message was Put.APPLORIGINDATA
: Application data relating to origin.GROUPID
: Group identifier.MSGSEQNUMBER
: Sequence number of logical message within group.OFFSET
: Offset of data in physical message from start of logical message.MSGFLAGS
: Message flags.ORIGINALLENGTH
: Length of original message.