The Unified Modeling Language User Guide

1
The Unified Modeling Language User Guide

• Chapter 6
• Common Mechanisms

2
Chapter 6 Topics

• Overview
• Terms and concepts
• Common modeling techniques

3
Overview

• All languages evolve over time. UML is no
  different.
• UML is an extensible language. It allows
  developers to add features that are not a core
  part of the language.
• Added meaning is attached to existing UML
  artifacts by the use of notes, stereotypes,
  tagged values and constraints.

4
Terms and Concepts

• A note is
• A means by which comments may be attached to a
  UML element (artifact).
• A note is itself an artifact.
• Graphically represented by a rectangle with a
  dog-eared corner, together with textual or
  graphical content.
• Attached to the artifact that is being clarified
  with a dashed line.
• Necessary because some information cannot be
  communicated exclusively with pictures.

5
Terms and Concepts
6
Terms and Concepts

• An stereotype is
• A metatype, because it is used to create the
  equivalent of a new type in UML.
• A concise comment.
• In its simplest form enclosed in guillemets (ltlt
  gtgt).
• In its more complex form an icon.
• Attach the stereotype to whichever predefined UML
  artifact is closest to the new type you are
  attempting to model.

7
Terms and Concepts

• An tagged value is
• An extension of the properties of a UML element.
• Represented as a string enclosed in braces.
• The string is in the form name value.
• Placed below the name of the UML element whos
  properties are being extended.
• Commonly used in configuration management. For
  example
• programmer John Johnson
• version 4.56
• Not one of the more commonly used features of UML.

8
Terms and Concepts
9
Terms and Concepts

• A constraint is
• An extension of the meaning of a UML element.
• A means of adding new rules to existing ones.
• An indication of condition(s) that must be true
  in order for the model to work.
• Represented as a string encloses in braces and
  placed near the associated element.
• Alternatively represented as a note.

10
Terms and Concepts
11
Common Modeling Techniques

• Modeling comments
• If a comment is lengthy, put the comment in an
  external document and then refer to the document
  in a note.
• Think of a note as a digital sticky note.
• Modeling stereotypes
• Only use stereotypes when UML does not already
  provide a mechanism to communicate the desired
  information.
• Use short meaningful names for your stereotypes.

12
Common Modeling Techniques

• Modeling tagged values
• Only use tagged values when UML does not already
  provide a mechanism to communicate the desired
  information.
• Tagged values defined for one kind of element
  apply to all of its children.
• Modeling constraints
• Only use constraints when UML does not already
  provide a mechanism to communicate the desired
  information.
• Use short, meaningful descriptions for
  constraints.