[zeromq-dev] zmq_reactor API question

Wed Aug 11 23:01:19 CEST 2010

Let me see if I understand you correctly. After playing around with the way I want to implement a processing pipeline, I have realized I will need the following in each node (all of this running in one thread in one process):

1.     A pull socket to receive incoming requests.

2.     An inproc req/rep pair, to pass things from the "receiving front-end" to the "processing back-end" (I do this to create the illusion of synchronous processing when in reality everything is asynchronous underneath).

3.     A push socket to pass requests down the pipeline.

4.     A pub socket to periodically publish a heartbeat and statistics.

5.     A sub socket to subscribe to administrative commands.

I guess the idea is that I could create this "mega-device" using zmq_reactor?

Gonzalo Diethelm 

________________________________

From: zeromq-dev-bounces at lists.zeromq.org [mailto:zeromq-dev-bounces at lists.zeromq.org] On Behalf Of Matt Weinstein
Sent: Wednesday, 11 August, 2010 16:54
To: 0MQ development list
Subject: Re: [zeromq-dev] zmq_reactor API question

ØMQ devices are ordinarily used to connect two sockets to e.g. solve the back-to-back bind problem, or to perform other simple transfer operations.

You can construct more complex devices yourself by building the poll vectors and doing the housekeeping.  These devices can be used for things like timeout/recovery, server pooling, failover, load balancing, etc.

zmq_reactor is a helper library that implements an event driven (callback/reactor) paradigm on top of zmq_poll(), offering support for simple polling strategies (priority order, downstream polling, etc.)   

I consider it a first generation model, but it's pretty useful as it stands.

Best,

Matt

On Aug 11, 2010, at 4:28 PM, gonzalo diethelm wrote:

Matt, allow me to reply with a request: could you provide a little more information on what the use case for zmq_reactor is? I reviewed the samples on the git repo but I am not sure exactly what your goals are with the code (at a very high level). Forgive my being obtuse...

Thanks and best regards.

Gonzalo Diethelm

________________________________

From: zeromq-dev-bounces at lists.zeromq.org [mailto:zeromq-dev-bounces at lists.zeromq.org] On Behalf Of Matt Weinstein
Sent: Wednesday, 11 August, 2010 14:27
To: zeromq-dev at lists.zeromq.org
Subject: [zeromq-dev] zmq_reactor API question

Is the linked list form of zmq_reactor_t too complex? 

The current linked-list form of the zmq_reactor interface was conceived of to allow easy manipulation of the linkages on the fly, primarily through policy callbacks.  However, that rationale no longer applies because policies have been replaced by the IOP format we have today.

I am leaning toward re-writing the interface to zmq_reactor to mirror zmq_poll:

          int zmq_reactor_poll (zmq_reactoritem_t *items, int nitems, long timeout);

We are probably early enough in the usage and evolution of the library to change this easily.  This will eliminate a lot of structural complexity without a lot of downside. 

Finally, we could always allow "poll block chaining" in future versions if this were a necessary feature.

Please let me know what you think?

I'm leaning in favor of this change, so please object strongly if it's important.

If I don't hear serious objections I will start branching this PDQ.

RSVP,

Thank you,

Best,

Matt

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