LESSON 9 - Microservices and API Integration

Monolithic Architecture

A traditional application architecture where all components (user interface, business logic, data access layer) are tightly coupled and deployed as a single, indivisible unit.

1. Simple to develop

2. Easy to develop

3. Straightforward testing

Pros of Monolithic Architecture:

1. Must scale the entire application

2. Slow development cycles for large teams

3. Difficult to adapt to new technologies

4. A bug in one module can bring down entire application

5. Large deployments, high risk

Cons of Monolithic Architecture:

Microservices Architecture

An architectural style that structures an application as a collection of small, independent, and loosely coupled services. Each service is self-contained, focuses on a single business capability, and communicates with other services, typically through lightweight APIs.

1. Single Responsibility Principle

2. Decentralization

3. Loose Coupling

4. Independent Deployment

5. Polyglot Persistence

6. Polyglot Programming

7. Bounded Contexts

Core Principles of Microservices Architecture:

1. Increased Agility & Faster Time-to-Market

2. Improved Scalability

3. Enhanced Resilience

4. Technology Diversity (Polyglot)

5. Easier Maintenance

6. Better Organization for Large Teams

Benefits of Microservices:

1. Increased Operational Complexity

2. Distributed Data Management

3. Inter-service Communication Overhead

4. Debugging & Tracing

5. Initial Development Overhead

6. "Distributed Monolith" Risk

Drawbacks and Challenges of

Microservices:

REST APIs are used for [...]bound interfaces.

Is the most widely adopted architectural style for

building web services and microservices APIs.

1. Stateless

2. Client-Server

3. Cacheable

4. Layered System

5. Uniform Interface

What are the princile pf REST?

Stateless

Each request from client to server must contain all the

information needed to understand the request. The server should not store any client context between requests.

Client-Server

Clear separation of concerns between client and server.

Cacheable

Responses can be cached to improve performance.

Layered System

Can have multiple layers (e.g., load balancers, API gateways) between client and server.

Uniform Interface

A consistent way to interact with resources (e.g., using standard HTTP methods).

1. Resources

2. HTTP Methods

3. Representations

4. Stateless Communication

Key Components of RESTful APIs:

Resources

Anything that can be named and addressed (e.g., /users,

/products/123, /orders).

API Gateway

A single entry point for all external client requests to a microservices application. It acts as a reverse proxy, routing requests to the appropriate microservice.

1. Request Routing

2. Authentication & Authorization

3. Rate Limiting

4. Load Balancing

5. Caching

6. Protocol Translation

Functions of API Gateway

Monolithic

All-in-one application structure

Microservice

Many small independent services

API

A way for systems to communicate

RESTful

A specific type of web API that follows REST principles

OK

200

Created

201

No content

204

Bad Request

400

Unauthorized

401

Forbidden

403

Not Found

404

Unprocessable Content

422

Internal Server Error

500

1. GET

2. POST

3. PUT

4. DELETE

HTTP METHODS: