Composition and Aggregation

Has-a is a special form of Association where: It represents the Has-A relationship . It is a unidirectional association i.e. a one-way relationship. For example, here above as shown pulsar motorcycle has an engine but vice-versa is not possible and thus unidirectional in nature.19 Oca 2021

Composition is a concept that models a has a relationship . It enables creating complex types by combining objects of other types. This means that a class Composite can contain an object of another class Component . This relationship means that a Composite has a Component .

In knowledge representation, object-oriented programming and design (see object-oriented program architecture), is-a (is_a or is a) is a subsumption relationship between abstractions (e.g. types, classes), wherein one class A is a subclass of another class B (and so B is a superclass of A).

In database design, object-oriented programming and design (see object oriented program architecture), has-a (has_a or has a) is a composition relationship where one object (often called the constituted object, or part/constituent/member object) “belongs to” (is part or member of) another object (called the composite …