ConnTag (MQBYTE128) on Multiplatforms
A connection tag is conceptually similar to a connection identifier, but might span multiple related connections, identifying them as a single application instance. On Multiplatforms, the connection tag is generated by the queue manager at connection time.
For more information, see connection identifier and application instance.
Generated connection tags are semi human readable. That is, they can be displayed and filtered in MQSC as if strings in the local character set. Connections that are known by IBM MQ to be related are automatically assigned the same connection tag. This assignment is particularly important to application balancing.
The generated connection tag is visible in three ways:- In the output MQCNO structure on an MQCONNX call, when MQCNO_GENERATE_CONN_TAG is specified.
- In the output from DISPLAY CONN (or programmatic equivalents).
- In the output from DISPLAY APSTATUS (or equivalents).
The tag ceases to be valid when the application terminates or issues the MQDISC call.
See ConnTag (MQBYTE128) on IBM MQ for z/OS for information on using the connection tag on IBM MQ for z/OS.
Note: Connection tag values beginning with MQ in upper, lower, or mixed case in either ASCII or EBCDIC are reserved for use by IBM products. Do not use connection tag values beginning with these letters. Use the following special value if you require no tag:
- MQCT_NONE
- The value is binary zero for the length of the field and we should specify this value.
For the C programming language, the constant MQCT_NONE_ARRAY is also defined; this constant has the same value as MQCT_NONE, but is an array of characters instead of a string.
The length of the ConnTag field is given by MQ_CONN_TAG_LENGTH. This field is ignored if Version is less than MQCNO_VERSION_3.
Parent topic: Fields for MQCNORelated reference