Publisher faster than subscriber

hi everyone
what does crossbar do when the publisher is faster than one of the subscribers ?
thanks

Hi,

in short, without additional measures, unfortunately memory in the router will run away.

What we can do easily (relative): automatically kick a subscriber session with outgoing network buffers running away.

With a fast publisher, and one or some subscribers slower than the publisher, I can only see 2 options to react:

a) auto-kick subscriber sessions too slow for the publisher on the topic
b) auto-unsubscribe subscriber sessions too slow for the publisher on the topic
c) slow down the publisher

a) and b) can be done at the router level (only).
c) can only be done at the app level.

What option / requirements do you have in mind?

Cheers,
/Tobias

hi tobias
due just to one subscriber, an “out of memory” in the router is impossible in a distrubuted application, it will fall down all the system.
In this situation, is there at least on message emited by the router to inform that a subscriber is too slow ? or to indicate the level of network buffers in the router ?
In the case where the publised message is not critical, i would rather losing the message on one subscriber than closing its session.
Is there a sort of QoS level to define in this case ?

cheers

I don’t understand what you mean …

In this situation, is there at least on message emited by the router to inform that a subscriber is too slow ? or to indicate the level of network buffers in the router ?

no, we don’t have that currently. would be easy to add.

In the case where the publised message is not critical, i would rather losing the message on one subscriber than closing its session.
Is there a sort of QoS level to define in this case ?

that’s certainly an interesting alternative to kicking the slow subscriber session.

it would require publishing with a QoS level. currently, we only have 2 modes here: acknowledged and unacknowledged publications.

again, would be easy to add to crossbar.io - but we need to spec the QoS level and semantics in WAMP first …