Konzeptuelles Informationsmodell ^?

Potentiell relevante Objekttypen:

1. shops,
2. products,
3. inventories,
4. customers,
5. vendors,
6. ...

Potentiell relevante Ereignistypen:

1. customer orders,
2. product handovers,
3. customer payments,
4. replenishment orders,
5. deliveries,
6. payments for deliveries,
7. ...

These object and event types, with their participation associations, can be visually described in a UML class diagram, as shown below.

If a demand is greater than the current stock level, the difference counts as a lost sale. Whenever the stock level falls below a certain threshold (called reorder point)), the shop places a replenishment order with a quantity computed as the difference between an upper threshold (called target inventory) and the current stock level.

Konzeptuelles Prozess-Modell ^?

Conceptual event rules.

ON (event type)	DO (event routine)	Conceptual Event Rule Diagram
customer order	if there is sufficient inventory, then product handover, else customer departure
product handover	customer payment
customer payment	customer departure

Informations-Design-Modell ^?

The random variation of the lead time between a replenishment order and the corresponding delivery is modeled by a random variable with a uniform probability distribution between 1 and 3 days. The inventory is modelled as an object with three attributes: productQuantityInStock, reorderPoint and targetInventory. For simplicity, the model does not create replenishment order events, but instead it only schedules corresponding delivery events.

Consequently, we model just one object type: SingleProductShop, with three attributes quantityInStock (NonNegativeInteger), reorderPoint (NonNegativeInteger), and targetInventory (PositiveInteger). In addition, we model two event types:

• DailyDemand as an exogeneous event type with one attribute: quantity (PositiveInteger), and with the random variable function sampleQuantity and, as an exogeneous event type, with a recurrence function.
• Delivery as a caused event type with one attribute: quantity (PositiveInteger), and with the random variable function sampleLeadTime.

When the design model is implemented with an object-oriented programming language or framework, the participation associations between DailyDemand and SingleProductShop, as well as between Delivery and SingleProductShop, are represented with the corresponding reference properties shop and receiver. This is also the case when using the Object Event Simulation (OES) framework OESjs available from Sim4edu, where all object types are derived from the pre-defined OES category oBJECT and all event types are derived from the pre-defined OES category eVENT, as shown in the following diagram:

Prozess-Design-Modell ^?

IF demQuant <= shop.quantityInStock
THEN
  IF shop.quantityInStock − demQuant < shop.reorderPoint AND
       shop.quantityInStock > shop.reorderPoint
  THEN
    SET ordQuant TO shop.targetInventory −
          shop.quantityInStock - demQuant
    SCHEDULE Delivery( ordQuant) @ t + sampleLeadTime()
  DECREMENT shop.quantityInStock BY demQuant
ELSE (if demQuant > shop.quantityInStock)
  INCREMENT shop.lostSales BY demQuant − shop.quantityInStock
  SET shop.quantityInStock TO 0

INCREMENT shop.quantityInStock BY delQuant