Message queuing protocols: PGM vs UDP

Question

I need to have an intelligent conversation with several co-workers who have not yet been sold on embracing tried and trusted message queuing libraries such as MSMQ, ZeroMQ, RabbitMQ, etc and we need this type of messaging in our solution.

But to be able to sell to my colleagues the benefits of using established solutions, I need to understand the fundamental difference between PGM and UDP. What is PGM solving that UDP multicast could not solve?

Answer 1

The fundamental difference: UDP multicast is not reliable meaning messages may be lost or delivered out of order,If you want delivery guarantees you will have to build middleware on top to handle this.On the other hand PGM is a reliable multicast protocol meaning you get in order message delivery guarantees "out of the box" PGM