Template Method pattern in LLD - Architecture Diagram

System Overview - Template Method pattern

The Template Method pattern defines the skeleton of an algorithm in a base class, allowing subclasses to override specific steps without changing the overall structure. This pattern ensures consistent process flow while enabling customization of individual steps.

Architecture Diagram

  +-------------------+       +-------------------+
  |   AbstractClass   |<------|   ConcreteClass   |
  |-------------------|       |-------------------|
  | + templateMethod() |       | + stepOne()       |
  | + stepOne()       |       | + stepTwo()       |
  | + stepTwo()       |       +-------------------+
  +-------------------+

Components

AbstractClass

abstract_class

Defines the template method and default steps of the algorithm

ConcreteClass

concrete_class

Overrides specific steps of the algorithm to provide custom behavior

Request Flow - 5 Hops

Client → ConcreteClass

ConcreteClass → AbstractClass

AbstractClass → ConcreteClass

AbstractClass → ConcreteClass

ConcreteClass → Client

Failure Scenario

Component Fails:ConcreteClass

Impact:If overridden steps fail, the algorithm may produce incorrect results or throw errors.

Mitigation:Use default implementations in AbstractClass as fallback or handle exceptions in templateMethod() to maintain flow.

Architecture Quiz - 3 Questions

What is the main role of the AbstractClass in the Template Method pattern?

A Overrides specific steps of the algorithm

B Defines the overall algorithm structure

C Calls the client to start the process

D Handles database connections

Design Principle

The Template Method pattern promotes code reuse by defining a fixed algorithm structure in a base class while allowing subclasses to customize individual steps, ensuring consistent process flow with flexible behavior.