On Wed, 2017-12-06 at 14:38 +0100, Francesco wrote: > Hi Luca, > yes sorry: I mean in the case of multiple publishers. In such case > ZMQ will > apply fair-dequeueing of the per-publisher queues, right?
Yes, that's correct. > The messages I publish have a timestamp inside them and I would like > to > process, inside my SUBscriber the messages ordered by timestamp, but > of > course ZMQ cannot know about that... > > Francesco Yes you'd have to implement that in your application - but I'm not sure how well that can scale. > 2017-12-06 13:40 GMT+01:00 Luca Boccassi <luca.bocca...@gmail.com>: > > > On Wed, 2017-12-06 at 12:55 +0100, Francesco wrote: > > > Hi all, > > > As you know when using PUB/SUB model the order of arrival of > > > messages > > > at > > > SUB-side cannot be garantueed and generally speaking, the SUB > > > will > > > receive > > > messages out of order. This is a well known problem, see e.g.: > > > https://cloud.google.com/pubsub/docs/ordering > > > > > > My question is: in case in the SUB you need strict time ordering, > > > are > > > you > > > aware of any good C++ implementation of a reordering queue? > > > > > > I used for other purposes moodycamel's queue ( > > > http://moodycamel.com/blog/2013/a-fast-lock-free-queue-for-c++) > > > which > > > is > > > thread-safe but it does not perform time-reordering. > > > > > > Thanks! > > > > > > Francesco > > > > What do you mean exactly? If you mean with multiple publishers > > writing, > > or ordering between different subscribers, then yeah it cannot be > > guaranteed. > > > > But from each individual publisher, to each individual subscriber, > > the > > ordering is guaranteed. Messages are written in a queue (first-in > > first-out), and then given to TCP, and then again received in a > > queue > > where the application fetches them from. > > > > -- > > Kind regards, > > Luca Boccassi > > _______________________________________________ > > zeromq-dev mailing list > > zeromq-dev@lists.zeromq.org > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev > > > > > > _______________________________________________ > zeromq-dev mailing list > zeromq-dev@lists.zeromq.org > https://lists.zeromq.org/mailman/listinfo/zeromq-dev -- Kind regards, Luca Boccassi
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