[zeromq-dev] Identities & PUB/SUB

[Paul Colomiets]

05.04.2011, 08:45, "Martin Sustrik" <sustrik at 250bpm.com>:
> Identities can be used with PUB/SUB to improve reliability of message
> distribution. However, the messages that are on flight during the
> disconnection/failure are dropped anyway. Moreover, if failure lasts for
> long enough, HWM on publisher is ultimately reached and new messages are
> discarded. Which makes the whole identity thing in PUB/SUB more or less
> useless.
>

Well, same applies to XREP/XREQ, and for PUSH/PULL. Sometimes
identities can assist routing, but it's quite hackish and rare solution.
So may be drop the whole identities feature?

> Even if there's limit for number of concurrent subscribers, the fact
> that "session" remains open even though underlying TCP socket is closed
> means the same scenario would quickly exhaust the session limit and
> create a DoS situation for other users.

I don't use zeromq in the wild (I mean open to external world) so it isn't real
problem for me. For those who have you probably could give an option. But
for external users you usually need to develop a reliable protocol anyway :).

--
Paul