[zeromq-dev] Advice how to implement QoS for ROUTER-ROUTER or ROUTER-DEALER devices.

[Pieter Hintjens]

I'm going to assume this is your first real work with ZeroMQ (based on
your earlier question about binding), and so I'm going to point you to
the FAQ. http://zeromq.org/area:faq

Please do learn the basics by working through the examples, before
attempting anything complex.

On Tue, Sep 24, 2013 at 4:15 PM, Artem Vysochyn
<artem.vysochyn at gmail.com> wrote:
> I'm working on creating top-notch rpc-framework (further RPCF) on the base
> of jzmq/zmq  and faced with serious design issue. Here's the deal, in my
> RPCF I'm going to use devices, especially LRU-device (via ROUTER-ROUTER
> mechanism), and more trivial FAIR-device (via ROUTER-DEALER mechanism).
> Regardless of *-device I inevitably will face the challenge of addressing
> some variant of QoS, here's how:
>
> 1. ROUTER-ROUTER (LRU-device)
> -- remote_client sends request - a message via DEALER
> -- request comes to LRU-device: poller.pollin(int) == true
> -- now we consume a message from frontend ROUTER, and want to pass it
> further via backend ROUTER, ... but we can't because identity_storage
> doesn't host suitable identity.
> ** now we got a problem: we consumed message from socket but couldn't
> forward it further. Also we can't drop message because client expecting
> reply. So what to do?
>
> 2. ROUTER-DEALER (FAIR-device)
> -- remote_client sends request - a message via DEALER
> -- request comes to FAIR-device: poller.pollin(int) == true
> -- now we consume a message from frontend ROUTER, and want to pass it
> further via backend DEALER, ... but we can't because HWM is reached, so I
> get exception, catch it, and now what?
> ** now we got a problem: consumed message from frontend, but couldn't
> forward it further.
> Also we can't drop message because client expecting reply. So what to do?
>
> As you see, there's two main issues: what to do with a message which has
> been consumed from socket but wan't passed further because of some condition
> (in LRU case -- we failed to find suitable identity, for FAIR case -- HWM is
> reached on backend).
>
> Now, I'm here and asking for your advice regarding what to do with a
> message?
>
> So far, I implemented  mechanism which sends message back to its original
> sender with RETRY_CALL flag, and if receive_timeout wasn't being exceeded
> then client sends message again. But is this way to go? Maybe there're some
> other approaches which I don't see?
>
>
> As usual, appreciate for the help in advance,
>
>
>
>
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>