[zeromq-dev] pub/sub and multicast

[Goswin von Brederlow]

On Wed, Jul 23, 2014 at 08:45:37PM +0000, McMillan, Scott A wrote:
> Hi,
> 
> Sorry for the very basic question, I'm new to zeromq.
> 
> The FAQ (http://zeromq.org/area:faq#toc0) says "PUB does multicast."  How
> should I interpret this statement?  Does this mean that IP-level multicast
> is required to use the pub/sub pattern?

No. PUB will simply unicast each message to every connected peer. So
to you it looks like multicast since zmq hides the details from you.

> Looking at the examples, it looks like the protocol can be selected
> independently from the pattern?  E.g., several examples contain the
> following, which I interpret as the pub/sub pattern on top of TCP unicast:
> 
>   void *publisher = zmq_socket (context, ZMQ_PUB);
>   zmq_bind (publisher, "tcp://*:5563");
> 
> 
> If one wanted to use multicast, then the second line would be replaced
> with something like:
> 
>   zmq_bind (publisher, "pgm://...");
> 
> 
> Am I understanding this correctly?
> 
> Thanks,
> Scott

That is my understanding too.

MfG
	Goswin