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UML (Unified Modeling Language)

UML is a standard language for specifying, visualizing, constructing, and documenting the of software systems. UML was created by the Object Management Group (OMG). UML specification draft was proposed to the OMG in January 1997.

1. UML has become an OMG standard
2. UML is different from the other common programming languages such as C++, Java, COBOL, etc.
3. UML is a pictorial language used to make software blueprints.
4. UML can be described as a general-purpose visual modeling language to visualize, specify, construct, and document software system.
5. UML diagrams are not only made for developers but also for business users, common people, and anybody interested to understand the system. The system can be a software or non- software system
6. UML is not a programming language but tools can be used to generate code in various languages using UML diagrams.
7. UML has a direct relation with object-oriented analysis and design.
8. The goals for developing UML is to define some general-purpose modeling language, which all modelers can use and it also needs to be made simple to understand and use.

A CONCEPTUAL MODEL OF UML

A conceptual model can be defined as a model which is made of concepts and their relationships. A conceptual model is the first step before drawing a UML diagram. It helps to understand the entities in the real world and how they interact with each other.

The conceptual model of UML can be mastered by learning the following three major elements.

1. UML building blocks
2. Rules to connect the building blocks
3. Common mechanisms of UML

OBJECT-ORIENTED CONCEPTS

UML is an analysis and design of object-oriented (OO).

An object contains both data and methods that control the data. The data represents the state of the object. A class describes an object and they also form a hierarchy to model the real-world system. The hierarchy is represented as inheritance. The classes can also be associated in different ways as per the requirement.

Objects are the real-world entities that exist around us and the basic concepts such as abstraction, encapsulation, inheritance, and polymorphism all can be represented using UML.

UML is powerful enough to represent all the concepts that exist in object-oriented analysis and design.

UML diagrams are representation of object-oriented concepts only.

Fundamental concepts of the object-oriented world:

1. Objects − Objects represent an entity and the basic building block.
2. Class − Class is the blue print of an object.
3. Abstraction − Abstraction represents the behavior of a real-world entity.
4. Encapsulation − Encapsulation is the mechanism of binding the data together, hiding them from outside world.
5. Inheritance − Inheritance is the mechanism of making new classes from existing ones.
6. Polymorphism − Is the mechanism to exists in different forms. The ability of different objects to respond in a unique way to the same message.

OO ANALYSIS AND DESIGN

Analysis means the investigation of objects; Design means the collaboration of identified objects.

The purpose of OO analysis is to identify objects of a system to be designed. This analysis is also done for an existing system. After identifying the objects, their relationships are identified and finally the design is produced.

Purpose of OO analysis and design:

1. Identifying the objects of a system.
2. Identifying their relationships.
3. Making a design, executable using OO languages.

Steps where the OO concepts are applied and implemented.

OO Analysis → OO Design → OO Implementation

The above three points can be described in detail as −

•  OO Analysis - The objects should be identified with responsibilities. Responsibilities are the functions performed by the object. Each and every object has some type of responsibilities to be performed.
•  OO Design - The objects are collaborated according to their intended association.
•  OO Implementation - The design is implemented using OO languages such as Java, C++, etc.

Role of UML in OO Design

1. Things
2. Relationships
3. Diagrams

Things:

Things are the most important building blocks of UML. Things can be −

1. Structural
2. Behavioral
3. Grouping