UML Building blocks - Things

Structural Things

Structural things are the nouns of UML models.

These are the mostly static parts of a model, representing elements that are either conceptual or physical.

Class

A class is a description of a set of objects that share the same attributes, operations, relationships, and semantics.

• Attribute : An attribute is a named property of a class that describes a range of values that instances of the property may hold.  
• Operation : An operation is the implementation of a service that can be requested from any object of the class to affect behavior.

Use case

A use case specifies the behavior of a system or a part of a system and is a description of a set of sequences of actions, including variants, that a system performs to yield an observable result of value to an actor.

• Actor : An actor represents a coherent set of roles that users of use cases play when interacting with these use cases.

Interface

An interface is a collection of operations that specify a service of a class or component.

Collaboration

A collaboration defines an interaction and is a society of roles and other elements that work together to provide some cooperative behavior that's bigger than the sum of all the elements.

Active class

An active class is a class whose objects own one or more processes or threads and therefore can initiate control activity.

Component

A component is a physical and replaceable part of a system that conforms to and provides the realization of a set of interfaces.

Node

A node is a physical element that exists at run time and represents a computational resource.

Behavioral Things

Behavioral things are the dynamic parts of UML models.

These are the verbs of a model, representing behavior over time and space.

Interaction

An interaction is a behavior that comprises a set of messages exchanged among a set of objects within a particular context to accomplish a specific purpose.

State machine

A state machine is a behavior that specifies the sequences of states an object or an interaction goes through during its lifetime in response to events, together with its response to those events.

Grouping and Annotational Things

Grouping things are the organizational parts of UML models.

Package

A package is a general purpose mechanism for organizing elements into groups.

Annotational things are the explanatory parts of UML models.

Note

A note is simply a symbol for rendering constraints and comments attached to an element or a collection of elements.