Events distributed through the Event Notification Service (ENS) does not follow any specific queue or order. The reason behind this is that messages from inside the Saxo Infrastructure are distributed as soon as they are ready. Meaning that for example it would be entirely possible to get a "Order placed" event AFTER getting an "Order Filled" event for the same order. Even though this is unintuitive. Of course the "Order Placed" event will in fact happen before the "Order Filled" event, but there is no guarantee that they are sent out in that order or they are not delayed on the way.