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Before we can inquire on a queue, open it using the MQOPEN call and specifying MQOO_INQUIRE.

If you have clusters in which there are multiple instances of the same queue, the attributes that can be inquired depend on whether there is a local instance of the cluster queue, and on how the queue is opened.

If, on the MQOPEN call, in addition to specifying MQOO_INQUIRE, you also specify one of the options MQOO_BROWSE, MQOO_INPUT_*, or MQOO_SET, there must be a local instance of the cluster queue for the open to succeed. In this case we can inquire on all the attributes that are valid for local queues.

If, on the MQOPEN call, you specify only MQOO_INQUIRE, or MQOO_INQUIRE and MQOO_OUTPUT (but specify none of the options MQOO_BROWSE, MQOO_INPUT_*, or MQOO_SET, which always cause the local instance of a cluster queue to be selected), the instance opened is either:

• The instance on the local queue manager, if there is one, or

• An instance elsewhere in the cluster, if there is no local queue-manager instance

If the queue that is opened is not a local queue, only the attributes listed below can be inquired. The QType attribute has the value MQQT_CLUSTER in this case.

• DefBind

• DefPersistence

• DefPriority

• InhibitPut

• QDesc

• QName

• QType

To inquire on the DefBind attribute of a cluster queue, use the MQINQ call with the selector MQIA_DEF_BIND. The value returned is either MQBND_BIND_ON_OPEN or MQBND_BIND_NOT_FIXED. To inquire on the CLUSTER and CLUSNL attributes of the local instance of a queue, use the MQINQ call with the selector MQCA_CLUSTER_NAME or the selector MQCA_CLUSTER_NAMELIST respectively.

If you open a cluster queue with no fixed binding (that is, specifying MQOO_BIND_NOT_FIXED on the MQOPEN call, or specifying MQOO_BIND_AS_Q_DEF when the DefBind attribute of the queue has the value MQBND_BIND_NOT_FIXED), successive MQINQ calls might inquire different instances of the cluster queue.

 

Parent topic:

MQI and clusters

qc11070_

 

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