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An option on the MQOPEN call, the MQOO_BIND_ON_OPEN option, allows you to specify that, when there are multiple instances of the same queue within a cluster, the target queue manager needs to be fixed. That is, all messages put to the queue specifying the object handle returned from the MQOPEN call must be directed to the same queue manager using the same route.

If a local queue of a given name is defined for the cluster, an application that was previously putting to remote queue instances of the same name will not use the newly defined queue until the object handle returned from the original MQOPEN command is closed and reopened, unless MQOO_BIND_NOT_FIXED is in effect.

Use this option when you have messages with affinities. For example, if we need a batch of messages all to be processed by the same queue manager, specify MQOO_BIND_ON_OPEN when you open the queue. WebSphere MQ fixes the queue manager and the route to be taken by all messages put to that queue.

If you do not want to force all your messages to be written to the same destination, specify MQOO_BIND_NOT_FIXED on the MQOPEN call. This selects a destination at MQPUT time, that is, on a message-by-message basis.

Do not specify MQOO_BIND_NOT_FIXED and MQMF_SEGMENTATION_ALLOWED at the same time. If you do, the segments of your message might all be delivered to different queue managers, scattered throughout the cluster.

If you do not specify either MQOO_BIND_ON_OPEN or MQOO_BIND_NOT_FIXED, the default option is MQOO_BIND_AS_Q_DEF. Using MQOO_BIND_AS_Q_DEF causes the binding that is used for the queue handle to be taken from the DefBind queue attribute. See Queue definition commands.

We can also choose a destination queue manager, by specifying its name in the object descriptor on the MQOPEN call. In this way, we can select any queue manager, including the local one.

If you specify one or more of the options MQOO_BROWSE, MQOO_INPUT_*, or MQOO_SET on the MQOPEN call, there must be a local instance of the cluster queue for the open to succeed. If you specify one or more of the options MQOO_OUTPUT, MQOO_BIND_*, or MQOO_INQUIRE on the MQOPEN call, and none of the options MQOO_BROWSE, MQOO_INPUT_*, or MQOO_SET (which always select the local instance) 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

For full details about the MQOPEN call and how to use it, see the Application Programming Reference book.

• Resolved queue manager name
  

 

Parent topic:

MQI and clusters

qc11040_

 

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