2
Chapter .
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The Introduction to Use Cases contains an initial presentation of key notions, to get the
discussion rolling: "What does a use case look like?", "When do I write one?", and "What varia-
tions are legal?" The brief answer is that they look different depending on when, where, with
whom, and why you are writing them. That discussion begins in this early chapter, and continues
throughout the book
The Use Case Body Parts contains chapters for each of the major concepts that need to
mastered, and parts of the template that should be written. These include “The Use Case as a
Contract for Behavior” , “Scope” , “Stakeholders & Actors” , “Three Named Goal Levels” ,
“Preconditions, Triggers, Guarantees” , “Scenarios and Steps” , “Extensions” , “Technology &
Data Variations” , “Linking Use Cases” , and “Use Case Formats” .
Frequently Asked Questions addresses particular topics that come up repeatedly: “When are
we done?” , “Scaling up to Many Use Cases” , “Two Special Use Cases” ("CRUD use cases" and
"Parameterized use cases"), “Business Process Modeling” , “The Missing Requirements” , “Use
Cases in the Overall Process” , “Use Cases Briefs and eXtremeProgramming” , and “Mistakes
Fixed” .
Reminders for the Busy contains a set of reminders for those who have finished reading the
book, or already know this material, and want to refer back to key ideas. The reminders are
organized as “Each Use Case” , “The Use Case Set” , and “Working on the Use Cases” .
The End Notes contains four topics: “Appendix A: Use Cases in UML” , “Appendix B:
Answers to (some) Exercises” , “Appendix C: Glossary” , and “Appendix D: Reading” .
Heritage of the ideas in this book
Ivar Jacobson invented use cases in the late 1960s while working on telephony systems at
Ericsson. Two decades later, he introduced them to the object-oriented programming community,
where they were recognized as filling a significant gap in the development process. I took
Jacobson’s course in the early 1990's. The ideas here are generally compatible with Jacobson’s
descriptions, but I have slowly extended his model to accommodate recent insights regarding the
writing. While neither he nor his team used the words goal and goal failure, it became clear to me
over time that they had been using these notions in their teaching. In several comparisons, he and I
have found there are no significant contradictions between his and my models.
I constructed the Actors & Goals conceptual model in 1994 while writing use case guides for the
IBM Consulting Group. The Actors & Goals model explained a lot of the mystery of use cases, and
gave guidance as to how to structure and write use cases. It circulated informally since 1995 from
http://members.aol.com/acockburn, later at www.usecases.org, and it finally appeared in the
Journal of Object-Oriented Programming in 1997, entitled "Structuring use cases with goals".
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