Who Should Take This Course?

The Course at a Glance

Introduction

The Problem: Legacy Systems

The Strangler Pattern: A Solution

The Architecture of the Strangler Pattern

Strangler Pattern: A Detailed  Example

Key Insights and Implications

Strangler Fig Pattern

Introduction to the API Gateway Pattern

Advantages of API Gateway Pattern

API Gateway Pattern: An Example

Performance Implications

System Design Example

API Gateway Pattern

Introduction to BFF

The Problem: Traditional Backend Models

The Architecture of the BFF Pattern

BFF Pattern: An Example

System Design Examples

Backends for Frontends (BFF) Pattern

What is Service Discovery Pattern?

The Problem: Service Coordination in Distributed Systems

Service Discovery Pattern: A Solution

The Architecture of the Service Discovery Pattern

The Inner Workings of the Service Discovery Pattern

Service Discovery Pattern: An Example

Performance Implications and Special Considerations

Service Discovery Pattern

The Problem: The Struggles of Distributed Systems and Service Failures

The Circuit Breaker Pattern: An Effective Shield Against Cascading Failures

Circuit Breaker Pattern: An Example

Circuit Breaker Pattern

The Problem: Failure Propagation in Distributed Systems

The Bulkhead Pattern: A Solution

The Architecture

The Inner Workings

Bulkhead Pattern: A Example

Conclusion

Bulkhead Pattern

The Problem: Unreliable External Resources in Distributed Systems

The Retry Pattern: A Solution

The Architecture of the Retry Pattern

The Inner Workings of the Retry Pattern

Retry Pattern: An Example

Use Cases and System Design Examples

Retry Pattern

Introduction to the Sidecar Pattern

The Problem: Monolithic Application Management

A Solution to the Monolithic Mayhem

The Architecture of the Sidecar Pattern

Sidecar Pattern: Bringing Theory to Practice with an Example

System Design Examples: Bringing the Sidecar Pattern to Life

Sidecar Pattern

Introduction to Saga Pattern

The Problem: Traditional Transaction Models

The Saga Pattern: A Solution

The Architecture of the Saga Pattern

The Inner Workings of the Saga Pattern

Saga Pattern: A Example

Saga Pattern

The Problem: Managing Complex Interactions in Distributed Systems

Event-Driven Architecture: A Promising Solution

The Architecture of the Event-Driven Architecture Pattern

The Inner Workings of the Event-Driven Architecture Pattern

Event-Driven Architecture Pattern: An Example

Event-Driven Architecture Pattern

The Problem: Traditional CRUD Operations

CQRS Pattern: A Solution

The Architecture of the CQRS Pattern

The Inner Workings of the CQRS Pattern

CQRS Pattern: An Example

Issues, Special Considerations, and Performance Implications

CQRS (Command Query Responsibility Segregation)

The Problem: Configuration Management in a Microservices Architecture

The Solution: Configuration Externalization Pattern

Unveiling the Architecture: How Does Configuration Externalization Work?

Delving into Code: An Example

Considerations and Implications

Use Cases and Real-world Examples

Configuration Externalization Pattern

Embrace the Future of Software Architecture

Course Wrap-up

Grokking Microservices Design Patterns


The implementation of the Strangler Pattern begins by identifying a single functionality of the legacy system that can be rebuilt and redirected to the new system. 

Once a functionality is identified, it's duplicated in the new system, and traffic is rerouted to the new implementation using a Facade interface. This interface is the gatekeeper, directing incoming requests either to the new system or to the old one. Over time, more and more functionality is migrated to the new system, and traffic to the old system decreases until it's finally phased out. 

**Steps**:
1. **Identify Entry Points**: Choose parts of your legacy system you want to replace and build new services to replace old functionalities.
2. **Route Traffic**: Use a router/proxy to redirect traffic either to the old system or new service, based on what's been migrated.
3. **Incrementally Build & Replace**: Develop the new microservices and slowly replace old functionalities.
4. **Retire the Old**: Once all functionalities have been taken over by the new system, safely retire the old system.


This progressive approach minimizes risk and allows for continuous delivery and integration, making it possible to replace the legacy system without disrupting normal business operations.