[zeromq-dev] [PATCH] Publisher side filtering

Gerard Toonstra gtoonstra at gmail.com
Wed Jan 19 16:26:27 CET 2011

On Wed, Jan 19, 2011 at 3:31 PM, Martin Sustrik <sustrik at 250bpm.com> wrote:

>  This is patched against "sub-forward" branch.
>> With this fix, the subscriptions are always forwarded upstream,
>> regardless of which process is terminated.
>> This strategy allows subscribers to resubmit their subscriptions on a
>> reconnection, but now that the session has no knowledge
>> of subscriptions, there are no unsubscribes sent upstream on behalf of a
>> subscriber when the subscriber goes away. In effect,
>> the only way to get rid of a subscription is by an explicit unsubscribe.
> I think the publisher should drop all the subscriptions when disconnection
> happens. That way it will receive fresh set of subscriptions upon
> reconnection with no need for explicit unsubscriptions.
If they are directly connected, that wouldn't be a problem. Except when
xpubs silently drop subscriptions, then devices that
are connected to other devices ( sub-xpub1-xsub1-xpub2-xsub2-pub ), the
xpub2 would never receive any unsubscribes if the sub disconnects
( or any pub connected to a broker ).  That's probably usually not a
problem, but only in circumstances where there are many
volatile / temporary subscriptions in use.


Gerard Toonstra
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