Message segmentation

 

Not supported in WebSphere MQ for z/OS.

Increasing the maximum message length as discussed in topic Increasing the maximum message length has some negative implications. Also, it can still result in the message being too large for the queue or queue manager. In these cases, we can segment a message. For information about segments, see Message groups.

The next sections look at common uses for segmenting messages. For putting and destructively getting, it is assumed that the MQPUT or MQGET calls always operate within a unit of work. We strongly recommend that you always use this technique, to reduce the possibility of incomplete groups being present in the network. Single-phase commit by the queue manager is assumed, but of course other coordination techniques are equally valid.

Also, in the getting applications, it is assumed that if multiple servers are processing the same queue, each server executes similar code, so that one server never fails to find a message or segment that it expects to be there (because it had specified MQGMO_ALL_MSGS_AVAILABLE or MQGMO_ALL_SEGMENTS_AVAILABLE earlier).

• Segmentation and reassembly by queue manager
  

• Application segmentation
  

• Application segmentation of logical messages
  

• Putting and getting a segmented message that spans units of work
  

 

Parent topic:

Handling messages greater than 4 MB long

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