Adv2 Scenario2

Approach #2, single aggregate

The numbers in the diagram correspond to the following steps:

1. The UI sends a command to register X and Y onto conference #157. The command is routed to the Conference aggregate with an ID of 157.
2. The Conference aggregate with an ID of 157 is re-hydrated from the data store.
3. The Order entity validates the booking (it queries the ConferenceSeatsAvailability entity to see if there are enough seats left), and then invokes the method to update the number of seats booked on the conference entity.
4. The ConferenceSeatsAvailability entity updates its total number of seats booked.
5. The updated version of the Conference aggregate is persisted to the data store.