Page 13 - AIS access_chang_ingraham

USING REA TO MODEL BUSINESS PROCESSES 11

Sales

Cash
Receipt

FIGURE 1-14 Sales-Cash Receipt Relationship

at most, many pieces of inventory can be sold. Hence, for the "Sales" entity, the minimum
cardinality is one, and the maximum cardinality is many.
In Figure 1-14, we see that the relationship between "Sales" and "Cash Receipt" is
(1,1) and (1,1). Each sale transaction has one, and only one, cash receipt, and each cash
receipt event is for one sale transaction only. All customers must pay in full at the time
when the transaction occurs, although Jesse accepts credit cards. In other words, there are
no accounts receivable and no partial payments, so the cardinalities are (1,1) at the "Sales"
side. In addition, at the "Cash Receipt" side, each cash receipt relates to one transaction
only since the customers must pay at the time of sale.
If Cherokee bills customers periodically (for a few transactions), then the cardinal-
ities would be (1,N) at the "Cash Receipt" side as indicated in Figure 1-15. In that case,
each cash receipt would be related to many sales transactions. Due to the fact that cus-
tomers could delay payments (i.e., monthly billing), Cherokee would have accounts
receivables. This would result in a scenario of accounts receivable as indicated by the
zero minimum cardinality at the "Sales" side. If customers still must pay in full, the max-
imum cardinality at the "Sales" side is one.
Figure 1-16 provides the complete REA diagram for Cherokee's revenue cycle. In
terms of the cardinalities between events and agents, the general case is (1,1) at the event
side and (1,N) at the agent side. Each sale transaction relates to one customer only, and
each customer can participate in many sale transactions. Here, the internal agent, Jesse, is

Sales
., ,
·v
(0, 1)

Duality

(1, N)

Cash
Receipt

FIGURE 1-15 Sales-Cash Receipt Relationship (with Accounts Receivable)