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ChaPter 2 • underStanding and modeling organizational SyStemS 35

Figure 2.15
A use case diagram representing a
Plan system used to plan a conference.
Catering

Caterer
Arrange
Speaker Conference

<< include >> Chair

Keynote Speaker Reserve
Speaker Room

<< include >> Reservations
Hotel

Register for
Conference

<< extend >>
Arrange Language
Translation

Participant

would be to register students, or, if working with a travel company, to make an airline,
hotel, car, or cruise reservation.
3. Blue is at sea level and is customarily used to depict user goals. This level often has the
greatest interest for users and is easiest for a business to understand. It is usually written
for a business activity, and each person should be able to do one blue level activity in any-
where from 2 to 20 minutes. Examples are register a continuing student, add a new cus-
tomer, place an item in a shopping cart, and order checkout.
4. Indigo or fish is a use case that shows lots of detail, often at a functional or subfunctional
level. Examples are choose a class, pay academic fees, look up the airport code for a given
city, and produce a list of customers after entering a name.
5. Black or clam, like the bottom of the ocean, are the most detailed use cases, at a subfunc-
tion level. Examples might be to validate secure logon, add a new field using dynamic
HTML, or use Ajax to update a web page in a small way.
A use case scenario example is shown in Figure 2.16. Some of the areas included are
optional and may not be used by all organizations. The three main areas are:
1. An area header that contains case identifiers and initiators
2. Steps performed
3. A footer area that contains preconditions, assumptions, questions, and other information