[zeromq-dev] Queue + "sequencer"

Martin Sustrik sustrik at fastmq.com
Fri Jun 12 09:12:35 CEST 2009

Hi Dragan,

> I was just wondering if anybody has experienced issue with various queue 
> mechanism and need to specify a unique sequence/id in that same queue ? 
> Is standard practice to use some external 'sequence generator' or 
> so,obtain an id and then insert it into queue,or there's any internal 
> mechanism where You may insert Your data into queue and the queue 
> server/manager/whatever will give You back the unique sequence/id of 
> that exact message in the queue ?

Assigning sequence numbers makes sense in a shared queue. Note that 0MQ 
has no in-build shared queue, instead you have to implement it yourself. 
It's pretty simple (pseudocode):

int eid = create_exchange ("E", scope_global);
create_exchange ("Q", scope_global);
while (true) {
     message_t msg;
     receive (&msg);
     send (eid, msg);

It's easy to attach a sequence number to the message after it is 
received and before it is sent further.


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