Reliable multicast

Jan 20, 2012 at 11:33 AM

Hi

I need pub/sub middleware that can deliver messages to subscribers in total order. That means that every subscriber receive messages in the same order. Is it possible with WSP event system? After reading documentation it seems that there is no such guarantee, is is right?

Coordinator
Jan 20, 2012 at 6:28 PM

There is no guarantee of order or delivery. That said, the only time events can get out of order is when there is some failure (usually network), an event is dequeued to send on (which fails) so the event is re-queued. Events being lost can occur when the Wsp process is killed or when a network connection can't be re-established within the configured amount of time. We can run in production for months and never hit these situations.

Wsp is analagous to UDP but much more reliable. You can always layer your own reliability layer on by using a request/response paradigm or just assigning a sequential number to your event.

Keith