TechnologyDevelopment

UML diagrams

The UML diagram families and when to use each — structure vs behaviour.

UML (Unified Modeling Language) is a standard notation for modelling software. Its diagrams split into structural (what the system *is*) and behavioural (what it *does*).

Structural diagrams

Diagram	Shows
Class	Classes, their attributes, methods, and relationships
Object	Specific instances at one moment in time
Component	How code is packaged into components
Deployment	Hardware nodes and what runs on them

Behavioural diagrams

Diagram	Shows
Use case	Actors and the goals they pursue
Sequence	Messages exchanged between objects over time
Activity	A workflow or flowchart of steps
State machine	An object's states and the transitions between them

Reading a class box

+-------------------+
|      Account      |   <- name
+-------------------+
| - balance: int    |   <- attributes
+-------------------+
| + deposit(n)      |   <- operations
| + withdraw(n)     |
+-------------------+

Tip:Visibility markers: + public, - private, # protected.

Related:Software development process