[zeromq-dev] Problem with lost clients

[Diego Fons]

Hi Michel,

I'm aware of that, but I still don't know how that can help me with the
problem (may be I was not clear enough).

Using credit-based flow:
- The client connects with identity A.
- The client asks for chunks 0 to 9.
- The client dies (it means the socket will be re-created and re-connected).
- The server sends all the 10 chunks.
- The server detects the client is dead.
- The client reconnects with identity B (we can not reuse identities).
- The client asks for chunks 0 to 9 again.
- etc...

I know that if the server tries to send a chunk to client with identity A
after the crash, the chunks are dropped. But, what happen with the 10
chunks already sent to client with identity A?

Am I misunderstanding the guide? Is there anything implicit in the ROUTER
behavior that I missed? Should I assume that a message being dropped by the
ROUTER implies that all queued messages were already dropped?

Regards.

On Wed, Apr 22, 2015 at 1:10 PM, Michel Pelletier <
pelletier.michel at gmail.com> wrote:

> There's good information in the guide about solving these kinds of
> problems.  In particular:
>
> http://zguide.zeromq.org/hx:chapter7#State-Machines
>
> But read the whole chapter, it will explain credit based flow control and
> heartbeating as well.
>
> -Michel
>
> On Wed, Apr 22, 2015 at 8:01 AM, Diego Fons <diego.fons at intraway.com>
> wrote:
>
>> Hi,
>>
>> I'm building an application that consists of several clients using DEALER
>> sockets which connects to one server using ROUTER socket.
>>
>> The communication is quite simple:
>>   - Client sends a START message to server.
>>   - Server sends back an OK message to client.
>>   - Server starts sending a stream of data to server (until client asks
>> to stop it).
>>   - Client sends a STOP message to server.
>>   - Server sends back an OK message to client.
>>
>> The problem:
>>   - Client sends a START message to server.
>>   - Client crashes.
>>   - Server sends back an OK message to client.
>>   - Server starts sending a stream of data to server (until client asks
>> to stop it).
>>
>> The client never sends the STOP an the server will continue sending
>> messages until the HWM is reached. The problem is not how to know when a
>> client dies, I'm able to know it. The problem is how to release all the
>> resources used by ZMQ in order to handle the dead client, I mean, all those
>> enqueued messages.
>>
>> The only solution I see untill now, is to close the ROUTER and re-bind
>> it, but I face the problem that another client (several ones) could be
>> perfectly working ans if I close the ROUTER, may be some data could be lost.
>>
>> So, I have two options:
>>   1) Wait untill no clients are active and close the ROUTER.
>>   2) Try to change the pattern (possibly use a pattern with two
>> communication channels).
>>
>> Any comments about his?
>>
>> Regards.
>>
>> --
>> Diego Andrés Fons
>> Intraway Corp.
>> Solution Developer
>> AR Office: +54 (11) 6040 4000
>> US Office: +1 (516) 620 3890
>> Email: diego.fons at intraway.com
>>
>> Visit our website at http://www.intraway.com
>> Proud to be an ISO 9001:2008 certified company
>>
>> _______________________________________________
>> zeromq-dev mailing list
>> zeromq-dev at lists.zeromq.org
>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>
>>
>
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>


-- 
Diego Andrés Fons
Intraway Corp.
Solution Developer
AR Office: +54 (11) 6040 4000
US Office: +1 (516) 620 3890
Email: diego.fons at intraway.com

Visit our website at http://www.intraway.com
Proud to be an ISO 9001:2008 certified company
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