Relationships (association, aggregation, composition) in LLD - Architecture Diagram

System Overview - Relationships (association, aggregation, composition)

This system models different types of relationships between objects in software design: association, aggregation, and composition. It helps visualize how objects connect and depend on each other, which is key for designing clear and maintainable software.

Architecture Diagram

  +----------------+       +----------------+       +----------------+
  |   Object A     |-------|   Object B     |       |   Object C     |
  | (Association)  |       | (Aggregation)  |-------| (Composition)  |
  +----------------+       +----------------+       +----------------+
         |                        |                        |
         |                        |                        |
         +------------------------+------------------------+
                              Relationship Types

Components

Object A

class_object

Represents an object with an association relationship to Object B

Object B

class_object

Represents an object with aggregation relationship to Object C

Object C

class_object

Represents an object composed by Object B

Request Flow - 3 Hops

Object A → Object B

Object B → Object C

Object B → Object C

Failure Scenario

Component Fails:Object B

Impact:If Object B is destroyed, composed Object C is also destroyed; aggregated Object C remains

Mitigation:Ensure proper lifecycle management; use aggregation when independent lifecycle is needed

Architecture Quiz - 3 Questions

Which relationship means Object C cannot exist without Object B?

A Composition

B Association

C Aggregation

D Inheritance

Design Principle

This architecture demonstrates how different object relationships affect ownership and lifecycle. Association is a loose connection, aggregation implies shared ownership but independent lifecycle, and composition means strong ownership with dependent lifecycle. Understanding these helps design clear and maintainable object models.