[zeromq-dev] looking inside ZMQ queue

[diffuser78]

Ok, so once ZMQ sends to transport, zmq removes it from its internal queue.
Is there a way to know when would ZMQ do that ? Or may be build one ? The
customers of my lib want TCP like semantics and I need to tell if the
buffer is copied successfully to the kernel.

Any help on this is greatly appreciated.

Thanks.

DJ
On Fri, Jul 27, 2012 at 3:46 PM, Bennie Kloosteman <bklooste at gmail.com>wrote:

> Like most systems ZeroMQ will just send the message to the transport when
> the transport has received the message ( eg TCP/IP )it is removed from
> ZeroMQ. There are no guarantees it has even been sent , yet alone that the
> transport layer on the other side has the message.  This is pretty standard
> TCP/IP provides no guarantees the other service has received the message (
> only the receiver TCp/IP stack) so you need to code this in your
> application logic.
>
> Also if you are persisting you do not need a light weight system ,
> persistence is always slow and heavy , killing any performance ( Normally
> non persistent messaging systems do at least 10* the messages / second to
> persistent ones) . For persistence I would use a queue like MSMQ or the IBM
> equivalent   . Queues also help in knowing if the other side has received
> it.
>
> Ben
>
>
>
> On Sat, Jul 28, 2012 at 2:27 AM, diffuser78 <diffuser78 at gmail.com> wrote:
>
>> Sorry about my ignorance and laziness. I read this on the FAQ page:
>>
>>
>> *How do I determine how many messages are in queue?*
>>
>> *This isn't possible. At any given time a message may be in the ØMQ
>> sender queue, the sender's kernel buffer, on the wire, in the receiver's
>> kernel buffer or in the receiver's ØMQ receiver queue. Furthermore, a ØMQ
>> socket can bind and/or connect to many peers. Each peer may have different
>> performance characteristics and therefore a different queue depth. Any
>> "queue depth" number is almost certainly wrong, so rather than provide
>> incorrect information the library avoids providing any view into this data.
>> *
>> I had a related question but not same as above.
>>
>> When ZMQ sent this message over TCP to the receivier and when receiver
>> did a FIN/ACK indicating that it is ACK'ing to the finish of the
>> tranmission of byte transfer, it indicates that the transport layer on the
>> other end got the message. Does ZMQ keep tab of this ? When does sender ZMQ
>> removes this message from its internal buffer. *I am only interested in
>> knowing (in YES or NO) whether this message is in sender zmq buffer or not
>> *. Is that possible ? If you can point me out, I can create a patch for
>> it and send for review.
>>
>> Any thoughts are greatly appreciated.
>>
>> DJ
>>
>> On Fri, Jul 27, 2012 at 11:16 AM, Ian Barber <ian.barber at gmail.com>wrote:
>>
>>> On Fri, Jul 27, 2012 at 6:26 PM, diffuser78 <diffuser78 at gmail.com>
>>> wrote:
>>> > What I want to know is that, ZMQ might have returned success upon
>>> buffering
>>> > the message. But what if message is still in the queue and has not been
>>> > delivered to the receiver for some reasons (say slow receiver). Is
>>> there a
>>> > way I can peek into ZMQ queue to find out if my message M that I had
>>> sent in
>>> > a non blocking way was indeed sent on the wire successfully? My lib
>>> needs to
>>> > acknowledge to the app if there was an error after some time T for it
>>> to
>>> > timeout on the message M.
>>>
>>> It could be lost in the network, or the other side could crash while
>>> processing. The best way is to send an acknowledgement back from the
>>> receiver (also using ZeroMQ) and use that to determine whether the
>>> other side has received and processed it.
>>>
>>> Ian
>>> _______________________________________________
>>> zeromq-dev mailing list
>>> zeromq-dev at lists.zeromq.org
>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>>
>>
>>
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>
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