When the Broker receives an event with a sequence number that has not been set or is set to zero, it assumes that event sequence numbering rules are not to be applied to the event. If your application does not wish to use publish sequence numbers, it simply should not set them or set them to zero.

Your application may set a non-zero publish sequence number for an event by calling the awSetEventPublishSequenceNumber function prior to publishing or delivering the event. The awDeliverAckReplyEvent and awDeliverNullReplyEvent functions allow you to specify a publish sequence number directly.

When the event is published or delivered, the Broker will discard the event if the sequence number is less than or equal to the highest sequence number received from that Broker client so far.