My first Publication Agile-Data-Warehouse-Design-eBook | Page 55

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Chapter 2
To which the stakeholders might reply:
Customer orders product?
The answer to “Who
does what?” is the
main clause of an
event
You now have what you need to begin modeling: a subject: customer, a verb:
orders, and an object: product. This subject-verb-object combination is called the
main clause of the event, and you will reuse it to ask most of the follow-up ques-
tions for discovering the “whole” story.
Focus on One Event at a Time
Stakeholders are
typically interested
in multiple events.
Many share the
same subject or
object
Keep stakeholders
focused on one
event (verb) at a
time
Not surprisingly, you will find when asking a question as open as “Who does
what?” that stakeholders can describe many subject-verb-object combinations that
are interesting to them. In fact, they will typically bombard you with the subjects,
verbs, and objects of several business events right off the top of their heads. Even
reframing the question with a single chosen subject, for example, “Doctors do
what?” or “Drivers do what?” can trigger a cascade of information. Stakeholders
typically have several events that they need to measure for any given subject, each
with a different verb. For instance, doctors prescribe medicines, but they also
diagnose conditions, perform procedures, and schedule appointments. Drivers may
deliver packages, but they also depart from depots, accept payments, and collect
returns. Each subject-verb-object combination represents a different event which
needs to be documented in its own BEAM ✲ table.
Getting an eager group of stakeholders to slow down and take things one event
(verb) at a time can take some discipline. Try to reassure them (and yourself) that
there will be plenty of time to capture all of this data, but you need to focus on one
event at a time until it is complete — with all of its details. Don't worry about the
stakeholders, they will not forget their other favorite events while you are
documenting the current one.
Identifying the Responsible Subject
Responsible
subjects (usually
whos) help you
discover
atomic-level
business events
Whenever possible, try to identify a responsible subject for the event’s main clause.
A responsible subject is a person or organization that actually performs the activity
that the verb describes. This is important as it helps you discover the detailed
atomic-level events of a business process rather than less flexible summary events
that may only address the current report requirements. For example, if stake-
holders are thinking too much about product reports they may respond “Product
generates revenue” but you want to get them thinking about the underlying busi-
ness process(es) by asking: “How does a product generate revenue? Who makes
that happen?” To which the stakeholders might respond: “Customer buys product”
or “Salesperson sells product”. Both of these are better subject-verb-object combi-
nations (main clauses) for an event that will help you identify the detailed transac-
tions that should be modeled and loaded into the data warehouse.