Design Patterns Explained

3O Part I • An Introduction to Object-Oriented Software Development
for the dissemination, that is, the distribution of the code) (see
Table 2-1). Each diagram shows the relationships among the different
sets of entities, depending upon the purpose of the diagram.
Table 2-1 UML Diagrams and Their Purposes
When You Are... Use the UML Diagram...
In the analysis phase
Looking at object
interactions
In the design phase
Looking at an object's
behaviors that differ
based upon the state
that the object is in
In the deployment
phase
Use Case Diagrams, which involve entities
interacting with the system (say, users and other
systems) and the function points that I need to
implement.
Activity Diagrams, which focus on workflow of
the problem domain (the actual space where
people and other agents are working, the subject
area of the program) rather than the logic
flow of the program.
Note: Since this book is principally focused on
design, I will not cover Use Case Diagrams or
Activity Diagrams here.
Interaction Diagrams, which show how specific
objects interact with each other. Since they deal
with specific cases rather than general situations,
they are helpful both when checking
requirements and when checking designs. The
most popular kind of Interaction Diagram is the
Sequence Diagram.
Class Diagrams, which detail the relationships
between the classes.
State Diagrams, which detail the different states
an object may be in as well as the transitions
between these states.
Deployment Diagrams, which show how different
modules will be deployed. I will not talk about
these diagrams here.