MDPER (10-digit signed integer)

Message persistence.

This indicates whether the message survives system failures and restarts of the queue manager. For the MQPUT and MQPUT1 calls, the value must be one of the following:

PEPER

Message is persistent.

This means that the message survives system failures and restarts of the queue manager. Once the message has been put, and the putter's unit of work committed (if the message is put as part of a unit of work), the message is preserved on auxiliary storage. It remains there until the message is removed from the queue, and the getter's unit of work committed (if the message is retrieved as part of a unit of work).

When a persistent message is sent to a remote queue, a store-and-forward mechanism is used to hold the message at each queue manager along the route to the destination, until the message is known to have arrived at the next queue manager.

Persistent messages cannot be placed on:

• Temporary dynamic queues

• Shared queues where the coupling facility structure level is less than three, or the coupling facility structure is not recoverable.

Persistent messages can be placed on permanent dynamic queues, predefined queues, and shared queues where the coupling facility structure level is 3, and the coupling facility is recoverable.

PENPER

Message is not persistent.

This means that the message does not normally survive system failures or restarts of the queue manager. This applies even if an intact copy of the message is found on auxiliary storage during restart of the queue manager.

In the special case of shared queues, nonpersistent messages do survive restarts of queue managers in the queue-sharing group, but do not survive failures of the coupling facility used to store messages on the shared queues.

PEQDEF

Message has default persistence.

• If the queue is a cluster queue, the persistence of the message is taken from the DefPersistence attribute defined at the destination queue manager that owns the particular instance of the queue on which the message is placed. Usually, all of the instances of a cluster queue have the same value for the DefPersistence attribute, although this is not mandated.

  The value of DefPersistence is copied into the MDPER field when the message is placed on the destination queue. If DefPersistence is changed subsequently, messages that have already been placed on the queue are not affected.

• If the queue is not a cluster queue, the persistence of the message is taken from the DefPersistence attribute defined at the local queue manager, even if the destination queue manager is remote.

  If there is more than one definition in the queue-name resolution path, the default persistence is taken from the value of this attribute in the first definition in the path. This could be:

  • An alias queue

  • A local queue

  • A local definition of a remote queue

  • A queue manager alias

  • A transmission queue (for example, the DefXmitQName queue)

  The value of DefPersistence is copied into the MDPER field when the message is put. If DefPersistence is changed subsequently, messages that have already been put are not affected.

Both persistent and nonpersistent messages can exist on the same queue.

When replying to a message, applications should normally use for the reply message the persistence of the request message.

For an MQGET call, the value returned is either PEPER or PENPER.

This is an output field for the MQGET call, and an input field for the MQPUT and MQPUT1 calls. The initial value of this field is PEQDEF.