The Agile Modeling (AM) Method

General Diagramming Guidelines

The diagramming guidelines presented here are applicable to all types of diagrams and are not specific to a single type of diagram. The terms bubbles, lines, and labels are used throughout:

  • Bubbles represent diagram elements such as class boxes, object boxes, use cases, and actors.
  • Lines represent diagram elements such as associations, dependencies, and transitions between states.
  • Labels represent diagram elements such as class names, association roles, and constraints.

Figure 1. Depicting crossing lines.

Diagramming guidelines: Crossing lines

Figure 2. Improving the attractiveness of a diagram.

Diagramming guidelines: Straight lines

Figure 3. Indicating uncertainty on a diagram.

Diagramming guidelines: Indicating uncertainty

  1. Avoid Crossing Lines
  2. Crossing Lines Jump One Another. When you need to have two lines cross one of them should “hop” over the other, using the notation that you see in Figure 1 borrowed from electrical-wiring diagrams.
  3. Avoid Diagonal or Curved Lines
  4. Apply Consistently-Sized Bubbles. In the first version of the diagram in Figure 2 the A bubble is larger than the others, drawing attention to it.
  5. Show Only What You Have To
  6. Prefer Well-Known Notation Over Esoteric Notation
  7. Reorganize Large Diagrams Into Several Smaller Ones
  8. Include Whitespace In Diagrams
  9. Focus on Content First, Appearance Second
  10. Cleanup to Rethink a Diagram
  11. Organize Diagrams Left to Right, Top to Bottom
  12. Set and Follow Effective Naming Conventions
  13. Apply Common Domain Terminology in Names
  14. Only Bring Language Naming Conventions into Design Diagrams
  15. Indicate Unknowns with a Question Mark. Figure 3 depicts two examples.
  16. Consider Adding Color to Your Diagrams


Material for this article was summarized from Chapter 2 of The Elements of UML 2.0 Style.

Recommended Reading

Modeling style: Elements of UML 2.0 Style The Elements of UML 2.0 Style describes a collection of standards, conventions, and guidelines for creating effective UML diagrams. They are sound, proven strategies 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 188 pages long and is conveniently pocket-sized so it’s easy to carry around.
Choose Your WoW! 2nd Edition This book, Choose Your WoW! A Disciplined Agile Approach to Optimizing Your Way of Working (WoW) – Second Edition, is an indispensable guide for agile coaches and practitioners. It overviews key aspects of the Disciplined Agile® (DA™) tool kit. Hundreds of organizations around the world have already benefited from DA, which is the only comprehensive tool kit available for guidance on building high-performance agile teams and optimizing your WoW. As a hybrid of the leading agile, lean, and traditional approaches, DA provides hundreds of strategies to help you make better decisions within your agile teams, balancing self-organization with the realities and constraints of your unique enterprise context.
The Object Primer 3rd Edition: Agile Model Driven Development (AMDD) with UML 2 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 fundamental programming and testing techniques for successful agile solution delivery. The book also shows how to move from your agile models to source code, 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 refactoringobject/relational mappinglegacy analysis, and database access coding) from my award-winning Agile Database Techniques book.