You do not need to use publisher sequence numbers if your only concern is whether or not a published or delivered event gets to the Broker. If your application's publish or deliver method returns successfully, the event was transmitted to the Broker. If the publish or deliver method fails, you can simply send the event again.

When you re-send an event, there is a small chance a duplicate event will be presented to the Broker. The Broker might successfully receive a published event, but then encounter some error that prevents it from notifying your application. Avoiding this situation can be important if your application is dealing with financial transactions, for example.

When your application uses publisher sequence numbers, it allows the Broker to recognize and discard duplicate events. When used properly, this eliminates the window of opportunity for the presentation of duplicate events to the Broker.