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# SSD Example - With SSD all systems are treated as a black box - The emphasis of the diagram is events that cross the system boundary from actors to systems ## Process Sale Scenario The diagram describes a scenario where a Cashier interacts with a system to process a sale. The Cashier's role is...

# SSD Example - With SSD all systems are treated as a black box - The emphasis of the diagram is events that cross the system boundary from actors to systems ## Process Sale Scenario The diagram describes a scenario where a Cashier interacts with a system to process a sale. The Cashier's role is represented as a stick figure, and the System is represented as a black box. ### Events The events that occur are as follows: **Cashier**|**System**|**Description** ---|---:|---| |MakeNewSale()|---|The Cashier starts a new sale. |||This event does not have return value because the System simply acknowledged the request. |EnterItem(itemID, quantity)|---|The Cashier enters an item, its ID, and quantity. |||The System responds with the item's description and total. |||This event can occur multiple times. |EndSale()|---|The Cashier ends the sale. |||The System responds with the total with taxes. |||This event does not have return value because the Cashier only acknowledges this event. |MakePayment(amount)|---|The Cashier makes a payment. |||The System responds with the change due and receipt. There are also messages with parameters, which represent abstract events. For example, the System will receive payment data via some mechanism which is not shown on the diagram. The System will then respond with the change due and receipt.