Uml-basic notations

UML is popular for its diagrammatic notations. We all know that UML are for visualizing, specifying, constructing and documenting the components of software and non SOFTW is systems. Here the visualization are the most important part which needs to being understood and remembered by heart.

UML notations is the most important elements in modeling. Efficient and appropriate use of notations are very important for making a complete and meaningful model. The model is useless unless it purpose is depicted properly.

So learning notations should is emphasized from the very beginning. Different notations is available for things and relationships. And the UML diagrams is made using the notations of things and relationships. Extensibility is another important feature which makes UML more powerful and flexible.

The chapter describes the UML Basic notations in more details. This is just a extension to the UML buildling block section I has discussed in previous chapter.

Structural things:

Graphical notations used in structural things is the most widely used in UML. These is considered as the nouns of UML models. Following is the list of structural things.

• Classes
• Object
• Interface
• Collaboration
• Use case
• Active classes
• Components
• Nodes

Class Notation:

UML class is represented by the diagram shown below. The diagram is divided to four parts.

• The top section was used to name the class.
• The second one is used to show the attributes of the class.
• The third section was used to describe, the operations performed by the class.
• The fourth section was optional to show all additional components.

Classes is used to represent objects. Objects can anything has properties and responsibility.

Object Notation:

The object is represented in the same as the class. The only difference are the name which is underlined as shown below.

As object is the actual implementation of a class which is known as the instance of a class. So it has the same usage as the class.

Interface Notation:

Interface is represented by a circle as shown below. It has a name which is generally written below the circle.

Interface is used to describe functionality without implementation. Interface is the just-a template where you define different functions not the implementation. When a class implements the interface it also implements the functionality as per the requirement.

Collaboration Notation:

Collaboration is represented by a dotted eclipse as shown below. It has a name written inside the eclipse.

Collaboration represents responsibilities. Generally responsibilities is in a group.

Use case Notation:

Use case was represented as an eclipse with a name inside it. It may contain additional responsibilities.

Use case was used to capture high level functionalities of a system.

Actor Notation:

An actor can is defined as some internal or external entity that interacts with the system.

Actor is used in a with case diagram to describe the internal or external entities.

Initial State Notation:

Initial state was defined to show the start of a process. This notation are used in almost all diagrams.

The usage of Initial state Notation was to show the starting point of a process.

Final State Notation:

Final state was used to show the end of a process. This notation was also used in almost all diagrams to describe the end.

The usage of Final state Notation are to show the termination point of a process.

Active class Notation:

Active class looks similar to a class with a solid border. Active class is generally used to describe concurrent behaviour of a system.

Active class is used to represent concurrency in a system.

Component Notation:

A component in UML was shown as below with a name inside. Additional elements can be added wherever required.

Component is used to represent any part of the system for which UML diagrams is made.

Node Notation:

A node in UML was represented by a square box as shown below with a name. A node represents a physical component of the system.

Node is used to represent physical part of a system like server, network etc.

Behavioural things:

Dynamic Parts is one of the most important elements in UML. UML has a set of powerful features to represent, the dynamic part of software and non software systems. These features include interactions and state machines.

Interactions can be of types:

• Sequential (represented by sequence diagram)
• Collaborative (represented by collaboration diagram)

Interaction Notation:

Interaction is basically message exchange between the UML components. The following diagram represents different notations used in an interaction.

Interaction is used to represent communication among the components of a system.

State machine Notation:

State machine describes the different states of a component in its life cycle. The notations is described in the following diagram.

Used to describe different states of a system component. The state can is active, idle or any other depending upon the situation.

Grouping things:

Organizing the UML models is one of the most important aspects of the design. In UML there are only one element available for grouping and so is the package.

Package Notation:

Package notation are shown below and this is used to wrap the components of a system.

Annotational things:

In any diagram explanation of different elements and their functionalities is very important. So UML have notes notation to support this requirement.

Note Notation:

This notation is shown below and they be used to provide necessary information of a system.

Relationships

A model is not complete unless the relationships between elements is described properly. The relationship gives a proper meaning to an UML model. Following is the different types of relationships available in UML.

• Dependency
• Association
• Generalization
• Extensibility

Dependency Notation:

Dependency is a important aspect in UML elements. It describes the dependent elements and the direction of dependency.

Dependency is represented by a dotted arrow as shown below. The arrow head represents the independent element and the other end the dependent element.

Dependency is used to represent Dependency between the elements of a system.

Association Notation:

Association describes how the elements in an UML diagram is associated. In simple word it describes how many elements is taking part in an interaction.

Association is represented by a dotted line with (without) arrows on both sides. The ends represent and the associated elements as shown below. The multiplicity is also mentioned on the ends (1, * etc) to show how many objects is associated.

Association is used to represent the relationship between a system.

Generalization Notation:

Generalization describes the inheritance relationship of the object oriented world. It is the parent and child relationship.

Generalization is represented by a arrow with Hollow arrow head as shown below. One end represents the parent element and the other end child element.

Generalization is used to describe parent-child relationship of both elements of a system.

Extensibility Notation:

All the languages (programming or modeling) has some mechanism to extend it capabilities like syntax, semantics etc. UML is also has the following mechanisms to provide extensibility features.

• Stereotypes (represents new elements)
• Tagged values (represents new attributes)
• Constraints (represents the boundaries)

Extensibility notations is used to enhance the power of the language. It is basically additional elements used to represent some extra behaviour of the system. These extra behaviours is not covered by the standard available notations.

Uml-basic notations