A feature is a small, client-valued function expressed in the form <action><result><object>.  As the name implies, features are an important aspect of Feature-Driven Development (FDD) (Palmer and Felsing 2002).  Figure 1 shows several features for the university system.  Features are very small and typically can be implemented within a few hours.

Figure 1. Features.

The features in Figure 1 are basically a formalized version, wording wise at least, of traditional features.  Another formalized approach is to write features as shall statements.  For example “calculate the average mark on a transcript” would be worded “The system shall calculate the average mark on a transcript”.   Although the wording changes slightly in the end features and shall statements are effectively the same thing in my experience.

Although one of the primary advantages of features is that their small size makes them easy to estimate and to implement their size also poses a problem in that one feature by itself rarely provides significant value to stakeholders.  The solution is to organize features into groups called “feature sets”.  Figure 2 depicts how the features of Figure 1 would be organized into three feature sets – Transcript, Enrollment, and Parking Passes.  As you can see each feature set contains two or more related features.

Figure 2. Feature sets.

From a requirements point of view features are to FDD as use cases are to the Rational Unified Process (RUP) and user stories are to XP – they’re a primary source of requirements and the primary input into your planning efforts.  However, from a size point of view feature sets are much closer conceptually to use cases.  Features are estimated and prioritized in a similar manner to user stories.   Because features are so simple to create it is common to use very simple tools – such as index cards or a spreadsheet – to capture them.

Source

This artifact description is excerpted from Chapter 7 of The Object Primer 3rd Edition: Agile Model Driven Development with UML 2.

Suggested Reading

• Artifacts for Agile Modeling: The UML and Beyond 
• Modeling Style Guidelines
• Why Extend the UML Beyond Object and Component Technology?

		The Object Primer 3rd Edition: Agile Model Driven Development with UML 2 is an important reference book for agile modelers, describing how to develop 35 types of agile models including all 13 UML 2 diagrams.  Furthermore, this book describes the techniques of the Full Lifecycle Object Oriented Testing (FLOOT) methodology to give you the fundamental testing skills which you require to succeed at agile software development.  The book also shows how to move from your agile models to source code (Java examples are provided) as well as how to succeed at implementation techniques such as refactoring and test-driven development (TDD).  The Object Primer also includes a chapter overviewing the critical database development techniques (database refactoring, object/relational mapping, legacy analysis, and database access coding) from my award-winning Agile Database Techniques book.
		Agile Modeling: Effective Practices for Extreme Programming and the Unified Process is the seminal book describing how agile software developers approach modeling and documentation.  It describes principles and practices which you can tailor into your existing software process, such as XP, the Rational Unified Process (RUP), or the Agile Unified Process (AUP), to streamline your modeling and documentation efforts.  Modeling and documentation are important aspects of any software project, including agile projects, and this book describes in detail how to elicit requirements, architect, and then design your system in an agile manner.
		The Elements of UML 2.0 Style describes a collection of standards, conventions, and guidelines for creating effective UML diagrams. They are based on sound, proven software engineering principles that lead to diagrams that are easier to understand and work with.  These conventions exist as a collection of simple, concise guidelines that if applied consistently, represent an important first step in increasing your productivity as a modeler.  This book is oriented towards intermediate to advanced UML modelers, although there are numerous examples throughout the book it would not be a good way to learn the UML (instead, consider The Object Primer).  The book is a brief 188 pages long and is conveniently pocket-sized so it's easy to carry around.

Translations

• Japanese

Let Us Help

We actively work with clients around the world to improve their information technology (IT) practices, typically in the role of mentor/coach, team lead, or trainer.  A full description of what we do, and how to contact us, can be found at Scott W. Ambler + Associates.