Background
The database is down, so orders received from the shop cannot be processed immediately
Source
User
Stimulus
Sends an order to the shop
Reaction
The system detects the database is down and queues the order for 1 day. As soon as the database is back up, the queued orders are processed
Metric
If the database downtime is less than 1 day, the number of orders received must be equals to the number of orders queued.