[zeromq-dev] a pub with multiple subs starting sequentially

Martin Sustrik sustrik at 250bpm.com
Mon Nov 1 09:09:13 CET 2010


No. Identity identifies a particular instance of application. If you 
have two applications with the same identity, it's a bug in your 
application and 0mq will kill your connections.

Martin

On 11/01/2010 09:05 AM, Shaofeng Yang wrote:
> That's for one sub. Can it work with multiple subs? For example, sub1
> with its IDENTITY connects to the pub and later sub2 with its identity
> connects to the pub. then sub2 gets disconnected and then the pub
> starts to publish data, which will be received by sub1. some time
> later, sub2 re-connects to the pub. Can sub2 still receive the data
> received by sub1? Actually this is my original question since my
> program was written like this.
>
> Thanks,
> James
>
>
> On Mon, Nov 1, 2010 at 3:49 AM, Martin Sustrik<sustrik at 250bpm.com>  wrote:
>    
>> On 11/01/2010 08:46 AM, Shaofeng Yang wrote:
>>      
>>> Thanks for your quick response, Martin. Do you think it might make it
>>> work once zmq moves to publisher side filtering. in this case, the sub
>>> can register itself first and then gets disconnected. it will receive
>>> the lost messages when it re-connects to the pub later. of course, it
>>> will have limited queue size/time out for the subs.
>>> or what's the best model/implementation for this case.
>>>
>>>        
>> You can do it even now. Set the identity (ZMQ_IDENTITY) on the subscriber
>> socket, then connect to the publisher. Given that the subscriber socket has
>> name, publisher is able to say that a new connection being made is actually
>> a reconnection and send it all the pending data. You'll never get messages
>> that were sent before you connected for the first time though.
>>
>> Martin
>>
>>      




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