Usefull for slave instance, as they never directly access the system.

Most of the time, they have no status to report.

It should allow to get more conflict in case of concurrent transaction.

Do not show the expected state but only the "known" instance status, based on
SlapTool connection logs.

It allows to propagate the date change in the simulation without having frozen
movement.

It is needed by the open order simulation alarm, which uses the indexation
timestamp.

One is enough.

Change the ticket resource and inform the customer.

Cancel invoice if user removes his instances.