[zeromq-dev] socket call back when using the zmq_loop

Martin Sustrik sustrik at 250bpm.com
Fri Dec 18 17:26:06 CET 2009

Hi Sebastien,

> I playing with zeromq 2.0 and I would like to read/write several zmq
> socket in the same thread. I saw an interesting function call loop but I
> don't know how to register callback on zmq socket. Is there a way to do
> that or must I call explicitly zmq_poll with my zmq socket list?

There are no callbacks in 0MQ so when dealing with several sockets you 
have to use zmq_poll.

However, each 0MQ socket can actually manage arbitrary number of 
underlying POSIX sockets, e.g. server application handling 10,000 client 
connections needs only a single 0MQ socket.

Also, single socket can be used to talk to serveral destinations, i.e. 
you can do arbitrary number of zmq_bind's and zmq_connect's on a single 
0MQ socket.

The only case where you need multiple 0MQ sockets is when using multiple 
messaging patters simultaneously from the same thread, say both 
request/reply and publish/subscribe.


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