Nirvana provides message queue functionality through
the use of queue objects. Queues are the logical rendezvous
point for publishers (producers) and subscribers (consumers)
or data (events).
Message queues differ from publish / subscribe channels
in the way that events are delivered to consumers. Whilst
queues may have multiple consumers, each event is typically
only delivered to one consumer, and once consumed (popped)
it is removed from the queue.
Nirvana also supports non destructive reads (peeks)
from queues which enable consumers to see what events
are on a queue without removing it from the queue. Any
event which has been peeked will still be queued for
popping in the normal way. The Nirvana enterprise manager
also supports the ability to visually
peek a queue using it s snoop capability.
This section demonstrates how Nirvana message queues
work, and provide examples code snippets for all relevant
concepts.
