[zeromq-dev] Can't bind same ZMQ_UP/DOWNSTREAM multiple times.

[Martin Sustrik]

Oliver,

> Problem is, someone has to bind the address for anyone to be able to 
> talk to it.
> 
> See the attached diagram (sorry for slopping drawing, no mouse :-)
> 
> Circles = endpoints, oblongs = workers.
> 
> Right now, to implement the "mid" endpoint, you either need a device or 
> a device-like concentrator (a worker that binds an address and allows 
> the workers on the right to connect to it, and then forwards messages 
> from the left to the right).
> 
> Which is, essentially, duplicating lots of work.

Binding several sockets to a TCP port to get a multicast delivery is 
something TCP doesn't support. You'll either have to do with a device in 
the middle or use IP multicast (via PGM) which effectively turns your 
switch into the device. Using IP multicast has its own set of problems 
though.

Martom