My first Publication Agile-Data-Warehouse-Design-eBook | Page 66

Modeling Business Events
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Discrete Event
By a process of elimination, if an event is neither recurring nor evolving, it must be
discrete. You reconfirm this each time you discover a new detail by asking if its
example values can ever change. If details never change, or changes are handled as
new adjustment events, then the event remains discrete. In Figure 2-7 both the
ORDER DATE and the DELIVERY DUE DATE (if applicable) are known at the
time of an order and do not change, so the order events, as modeled so far, are
discrete.
Discrete events
contain details that
do not change
Who?
Once you have identified the story type it’s time to double-back (to the top of the
7Ws flowchart in Figure 2-2) and find out whether any other whos are associated
with the event. The general form of a who question is “Subject Verb Object
from/for/with who?” Using the current subject, verb and object you might ask:
Ask a who question
to see if anyone
else is involved
CUSTOMER orders PRODUCT from whom?
To which the stakeholder might reply:
Salesperson
If so, you add the new who to the table and ask for example salespeople to match
the existing event stories. E.g., to continue a group themed story you might ask:
Is there always just one SALESPERSON responsible for the order?
In Figure 2-8, the event stories introduce you to some of Pomegranate’s finest sales
personnel, but also shows that orders can be made without a salesperson, and that
some orders are handled by sales teams rather than individual employees (continu-
ing the group story theme).
Figure 2-8
Adding a second
who detail