[zeromq-dev] 0MQ experimental OpenPGM support

Martin Sustrik sustrik at fastmq.com
Tue Jan 20 17:23:03 CET 2009


>> Do we know when data is lost?  Sorry if these questions are answered
>> somewhere already...
> Yes, data loss is detected inside OpenPGM and forwarded up to 0MQ.
> So there is not gap in the data stream without knowing about it.

To be more precise, there are two distinct functionalities here. First 
one reports "connection error" when there's a request from a consumer 
for data retransmit and the data are no longer available on the sender box.

On top of this functionality you can ask 0MQ to do auto-reconnect when 
connection fails, meaning that you won't be even notified when there's a 
problem due to network exhaustion. Transmission will proceed normally 
after the problem is solved. Still, consumer app may be interested in 
knowing that there are messages missing at some particular point in the 
queue (to clear last-value caches or whatever) thus we push a special 
message into the queue saying "there are messages missing at this point".

The auto-reconnect functionality is already implemented in 0.3.3 branch. 
I have a patch for the trunk in the mailbox and once it passes code 
review it'll be merged into the trunk.


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