1. How to run the kitchen service

1.1 How to change the dispatch policy

The configuration of the dispatch policy is "kitchenService.dispatchPolicy" defined in test/resources/application.yml. There are two possible values:

• matched: a courier is dispatched for a specific order and may only pick up that order.
• firstInFirstOut: a courier picks up the next available order upon arrival. If there are multiple orders available, pick up an arbitrary order. If there are no available orders, couriers wait for the next available one. When there are multiple couriers waiting, the next available order is assigned to the earliest arrived courier.

1.2 How to run

• cd /kitchen
• mvn test

2. Design Considerations

2.1 Key design consideration

• The preparation of the order and the courier's rush to the kitchen needs some time. We use DelayQueue to implement this.
• Different dispatch policy needs the different data structures to store the arrived courier for query efficiency. We bind the specific data structure with the DispatchPolicy.
• Courier needs to call some methods in some services. We still use Spring to manage the couriers for service injection automatically. The scope is prototype. Provider is used to create the courier instance.

2.2 Detailed design

1. OrderService ####API:

• receiveOrder: a. Call KitchenService::prepareOrder; b. Call CourierService::dispatchOrder
• deliverOrder: remove the order ####Structure:
• orders: HashMap

2. KitchenService ####API:

• prepareOrder: put the order into the preparingOrders
• pickOrder: a. remove the order from preparingOrders; b. Call DispatchPolicy::dispatch to get the Courier; c. Call Courier::deliverOrder
• arriveKitchen: Call DispatchPolicy ####Structure:
• preparingOrders: DelayedQueue

3. DispatchPolicy ####API:

• enQueue: put the Courier into waitingCourier
• dispatch: remove the courier from the waitingCourier ####Structure:
• waitingCourier: HashMap<OrderId, Courier> Or List

4. CourierService ####API:

• rest:
• dispatchOrder: move one courier from idleCourier to onTheWayCourier
• rushToKitchen: move the courier from onTheWayCourier to waitingCourier(Call KitchenService::arriveKitchen) ####Structure:
• idleCourier: List
• onTheWayCourier: DelayedQueue

5. Courier ####API:

• deliverOrder: a. Call OrderService::deliverOrder; b. Call CourierService::rest

6. StatisticsService