Things

Things in the UML 

There are four kinds of things in the UML:

Structural things

Behavioral things

Grouping things

Annotational 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. In all, there are seven kinds of structural things.

1.      Classes

2.      Interfaces

3.      Collaborations

4.      Use cases

5.      Active classes

6.      Components

7.      Nodes

Class: is a description of a set of objects that share the same attributes, operations, relationships, and semantics. A class implements one or more interfaces. Graphically, a class is rendered as a rectangle, usually including its name, attributes, and operations.

 

 

Interface is a collection of operations that specify a service of a class or component. An interface therefore describes the externally visible behavior of that element. An interface might represent the complete behavior of a class or component or only a part of that behavior.

An interface is rendered as a circle together with its name.

 

 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. Therefore, collaborations have structural, as well as behavioral, dimensions.

Graphically, a collaboration is rendered as an ellipse with dashed lines, usually including only its name

Usecase Use case is a description of set of sequence of actions that a system performs that yields an observable result of value to a particular actor.

 it is used to structure the behavioral things in a model. Graphically, a use case is rendered as an ellipse with solid lines, usually including only its name.

Active class is just like a class except that its objects represent elements whose behavior is concurrent with other elements. Graphically, an active class is rendered just like a class, but with heavy lines, usually including its name, attributes, and operations.

Component is a physical and replaceable part of a system that conforms to and provides the realization of a set of interfaces. Graphically, a component is rendered as a rectangle with tabs.

Node is a physical element that exists at run time and represents a computational resource, generally having at least some memory and, often, processing capability. Graphically, a node is rendered as a cube, usually including only its name.

Behavioral Things are the dynamic parts of UML models. These are the verbs of a model, representing behavior over time and space. In all, there are two primary kinds of behavioral things

• Interaction 
•  state machine

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. An interaction involves a number of other elements, including messages, action sequences and links

                        Graphically a message is rendered as a directed line, almost always including the name of its operation

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 responses to those events.State machine involves a number of other elements, including states, transitions, events  and activities

Graphically, a state is rendered as a rounded rectangle, usually including its name and its sub-states.

Grouping Things:-

1. are the organizational parts of UML models. These are the boxes into which a model can be decomposed
2. There is one primary kind of grouping thing, namely, packages.
   Package:-
   ·  A package is a general-purpose mechanism for organizing elements into groups. Structural things, behavioral things, and even other grouping things may be placed in a package
   ·  Graphically, a package is rendered as a tabbed folder, usually including only its name and, sometimes, its contents

Annotational things are the explanatory parts of UML models. These are the comments you may apply to describe about any element in a model.

A note is simply a symbol for rendering constraints and comments attached to an element or a collection of elements. Graphically, a note is rendered as a rectangle with a dog-eared corner, together with a textual or graphical comment