There are three ways to designate the order of messages on a data
queue:
- LIFO
- Last in, first out. The last message (newest) placed on the data queue
will be the first message taken off of the queue.
- FIFO
- First in, first out. The first message (oldest) placed on the data queue
will be the first message taken off of the queue.
- KEYED
- Each message on the data queue has a key associated with it. A message
can be taken off of the queue only by requesting the key with which it is
associated.