By-Publisher Event Ordering
The Broker normally guarantees that events from a single publishing client cannot be processed out of order. This has important implications when more than one Broker client is sharing the same event queue. The following table shows an example client event queue containing events received from three different publishing clients; Broker client A, Broker client B, and Broker client C.
Publishing Client | Event Queue Position |
Client A | 1 |
Client B | 2 |
Client A | 3 |
Client C | 4 |
Client B | 5 |
Client C | 6 |
Consider the following steps:
1. BrokerClient X receives the event from queue position 1 without acknowledging the event.
2. BrokerClient Y receives the event from queue position 2 without acknowledging the event.
3. When
BrokerClient Y then asks for another event, it is given the event from queue position 4 because the last event published by Client A has not yet been acknowledged. For more information on acknowledging events, see
Using Sequence Numbers.