[zeromq-dev] zmq proxy with INPROC as frontend and TCP as backend: is it feasible?

[Francesco]

Hi Stephen,

2017-03-31 15:49 GMT+02:00 Stephen Riesenberg <stephen.riesenberg at gmail.com>:
> Good deal. Also, a note on the number of threads issue, instead of
> monitoring sockets, everything is in your control inside this multithreaded
> component you're building, so the proxy that funnels messages should have a
> way to know how many threads are running. You'd want the same setup method
> that fires up the threads in the first place to pass that number to the
> publisher thread or some side channel that keeps state. And if threads come
> and go for some reason, you'd just need to keep track of when they start up
> and exit to update a counter. This is assuming that number is necessary as
> part of your design. If not, one less thing to worry about, right?

absolutely; moreover for now I'm assert()ing the connection of each
thread to the frontend socket of the proxy. So that the number of
threads I create is always matching the number of threads sending data
to the proxy, otherwise the program would abort.

I don't know if INPROC sockets can fail to connect for some reason or
not.. apparently no so far :)

thanks,
Francesco


>
> On Fri, Mar 31, 2017 at 5:55 AM Francesco <francesco.montorsi at gmail.com>
> wrote:
>>
>> Hi Stephen,
>> indeed I tried and the setup of that networking schema was faster than
>> I expected... and more importantly it just worked!!! :)
>> The only "limitation" I discovered is that you cannot do
>> zmq_monitor_socket() on the INPROC side of the PROXY.
>> So that I don't have a way to ask to the proxy how many threads have
>> connected to its frontend socket. However's that not a big issue...
>> and more importantly I can still monitor the backend socket which is
>> the one exposed via TCP to the rest of the world.
>>
>>
>> 2017-03-30 21:56 GMT+02:00 Stephen Riesenberg
>> <stephen.riesenberg at gmail.com>:
>> >...
>> > Though I'm not sure what you mean by "I would like to have all these
>> > thread
>> > appear as a unique endpoint to the outside world." Would this be through
>> > a
>> > topic name or some other piece of data? This also seems fine, but wasn't
>> > sure if that's what you meant.
>>
>> Well, I just meant that other components must be able to subscribe to
>> the events produced by all threads by doing subscribe to a single ZMQ
>> endpoint (i.e., the endpoint of the backend socket of the proxy)...
>> that may seem obvious but I just wanted to specify that.
>>
>> Thanks for your reply!
>>
>> Francesco
>>
>>
>>
>>
>>
>> >
>> > On Tue, Mar 28, 2017 at 7:39 AM Francesco <francesco.montorsi at gmail.com>
>> > wrote:
>> >>
>> >> Hi all,
>> >>
>> >> I'm trying to work out a problem in a multithreaded application and I
>> >> would like to use ZMQ to solve it.
>> >>
>> >> In particular I have a process with several threads that are
>> >> generating messages; each one has its own PUB socket.
>> >> I would like to have all these thread appear as a unique endpoint to
>> >> the outside world.
>> >>
>> >> For this reason I'm thinking of changing the PUB socket of each thread
>> >> to use the INPROC transport and then create a ZMQ proxy exposing an
>> >> XSUB frontend socket with INPROC transport and an XPUB backend socket
>> >> with TCP transport, for the external world.
>> >>
>> >> Do you think such kind of scenario would work?
>> >>
>> >> Thanks!
>> >> Francesco
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