Browsing and retrieving destructively

 

In this example, the application browses each of the logical messages within a group, before deciding whether to retrieve that group destructively.

The first part of this example is similar to the previous one. However, in this case, having browsed an entire group, we decide to go back and retrieve it destructively.

As each group is removed in this example, MQGMO_LOGICAL_ORDER is not used when looking for the first or only message in a group.

The following gives an example of browsing and then retrieving destructively:

GMO.Options = MQGMO_BROWSE_NEXT | MQGMO_COMPLETE_MSG | MQGMO_LOGICAL_ORDER
            | MQGMO_ALL_MESSAGES_AVAILABE | MQGMO_WAIT
do while ( GroupStatus == MQGS_MSG_IN_GROUP )
   MQGET
   /* Examine each remaining message in the group (or as many as
      necessary to decide whether or not to get it destructively) */
   ...

if ( we want to retrieve the group destructively )

   if ( GroupStatus == ' ' )
      /* We retrieved an ungrouped message */
      GMO.Options = MQGMO_MSG_UNDER_CURSOR | MQGMO_SYNCPOINT
      MQGET GMO.MatchOptions = 0
      /* Process the message */
      ...

   else
      /* We retrieved one or more messages in a group.  The browse cursor */
      /* will not normally be still on the first in the group, so we have */
      /* to match on the GroupId and MsgSeqNumber = 1.                    */
      /* Another way, which works for both grouped and ungrouped messages,*/
      /* would be to remember the MsgId of the first message when it was  */
      /* browsed, and match on that.                                      */
      GMO.Options = MQGMO_COMPLETE_MSG | MQGMO_SYNCPOINT
      MQGET GMO.MatchOptions = MQMO_MATCH_GROUP_ID
                             | MQMO_MATCH_MSG_SEQ_NUMBER,
           (MQMD.GroupId      = value already in the MD)
            MQMD.MsgSeqNumber = 1
      /* Process first or only message */
      ...

      GMO.Options = MQGMO_COMPLETE_MSG | MQGMO_SYNCPOINT
                  | MQGMO_LOGICAL_ORDER
      do while ( GroupStatus == MQGS_MSG_IN_GROUP )
         MQGET
         /* Process each remaining message in the group */
         ...

 

Parent topic:

Browsing messages in groups

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