My first Publication Agile-Data-Warehouse-Design-eBook | Page 74

Modeling Business Events
53
Figure 2-11
Adding a why detail
How?
The final “W” questions discover any how details. How refers to the actual mecha-
nism of the business event itself. You discover these details by asking a how ques-
tion using the main clause of the event:
You finish with how
questions
How does a CUSTOMER order a PRODUCT?
Often how details include transaction identifiers from the operational system(s)
that capture each event. If the stakeholders respond with:
A customer or salesperson creates an ORDER with an ORDER ID.
then you would add ORDER ID to the table as in Figure 2-12. ORDER ID might be
an equally good answer to other how questions such as: “How do you know that a
customer ordered a product; what evidence do you have?” or “How can you tell
one similar order from another?” With these questions you are explicitly asking for
operational evidence that these event stories exist and can be differentiated from
one another.
Transaction IDs
(how details) help
to differentiate
events
Figure 2-12
Adding a how detail