[zeromq-dev] Knowing number of peers in of publisher
bertrand.nouvel at gmail.com
Wed Aug 4 11:58:42 CEST 2010
2010/8/4 Steven McCoy <steven.mccoy at miru.hk>
> On 4 August 2010 13:09, Bertrand Nouvel <bertrand.nouvel at gmail.com> wrote:
>> I am quite new with 0MQ. PGM seems really nice.
>> I would have one question, I did not find reply in the FAQ/docs.
>> Does 0MQ provide a way to know the number of subscriber to a publisher ?
>> It would be really convenient in some case to start a broadcast when the
>> correct number
>> of peers have connected to the publisher.
> At the protocol level, if the peers are functioning bi-directionally like
> the TIB it would be possible to find an estimate of the number of receivers.
> However much like RV version 5 versions SASS 3 you really need to implement
> subscription logic above PGM, for market data this is usually required for
> auditing and entitlements.
> At the base level ZeroMQ strictly uses PGM as a uni-directional transport;
> the PGM usage does have an upstream for re-transmission requests but is
> technically possible to disable it completely and so you would not receive a
> single packet from receivers meaning that you must implement the
> subscription logic at the higher level.
As there was the "recovery_interval" I was somehow thinking that this
information might have been available.. But it is of course more efficient
to cast data without
having to wait explicitely for ack.
Thanks for your rapid reply.
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