🎬 Movie Catalog Microservices

A demonstration of microservices architecture using Spring Boot and Spring Cloud, featuring inter-service communication, service discovery with Eureka, and fault tolerance with Hystrix.

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📋 Table of Contents

• Overview
• Architecture
• Services
• Tech Stack
• Getting Started
• API Endpoints
• Key Concepts
• Configuration

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🎯 Overview

This project demonstrates a movie catalog system built with microservices architecture. Users can retrieve a personalized movie catalog that aggregates:

• Movie information from The Movie Database (TMDb) API
• User-specific ratings for each movie

The system showcases:

• Inter-service communication using RestTemplate and WebClient
• Service discovery with Netflix Eureka
• Fault tolerance with Netflix Hystrix circuit breakers
• Load balancing with client-side load balancing

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🏗️ Architecture

┌─────────────────────────────────────────────────────────────────┐
│                      Eureka Discovery Server                     │
│                         (Port: 8761)                             │
└─────────────────────────────────────────────────────────────────┘
                                ▲
           ┌────────────────────┼────────────────────┐
           │                    │                    │
           ▼                    ▼                    ▼
┌──────────────────┐  ┌──────────────────┐  ┌──────────────────┐
│  Movie Catalog   │  │   Movie Info     │  │  Ratings Data    │
│    Service       │◄─┤    Service       │  │    Service       │
│   (Port: 8081)   │  │   (Port: 8082)   │  │   (Port: 8083)   │
└──────────────────┘  └──────────────────┘  └──────────────────┘
        │                      │
        │                      ▼
        │              ┌──────────────────┐
        │              │   TMDb API       │
        │              │  (External)      │
        │              └──────────────────┘
        ▼
   Client Request
   GET /catalog/{userId}

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🔧 Services

Service	Port	Description
Discovery Server	8761	Eureka server for service registration and discovery
Movie Catalog Service	8081	Aggregates movie info and ratings; provides user catalog
Movie Info Service	8082	Fetches movie details from TMDb API
Ratings Data Service	8083	Provides user ratings for movies

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🛠️ Tech Stack

• Java 11 / Java 8
• Spring Boot 2.1.2
• Spring Cloud Greenwich
• Netflix Eureka - Service Discovery
• Netflix Hystrix - Circuit Breaker & Fault Tolerance
• RestTemplate - Synchronous HTTP Client
• WebClient - Reactive HTTP Client
• Maven - Build Tool

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🚀 Getting Started

Prerequisites

• Java 8 or higher
• Maven 3.x
• TMDb API Key (get one at themoviedb.org)

Installation

1. Clone the repository

   git clone https://github.com/SaketKothari/microservices-communication-discovery-and-fault-tolerance.git
   cd microservices-communication-discovery-and-fault-tolerance

2. Configure TMDb API Key

   Update the API key in movie-info-service/src/main/resources/application.properties:

   api.key=YOUR_TMDB_API_KEY

3. Start the services in order

   # Terminal 1: Start Discovery Server (must be first)
   cd discovery-server
   ./mvnw spring-boot:run
   
   # Terminal 2: Start Movie Info Service
   cd movie-info-service
   ./mvnw spring-boot:run
   
   # Terminal 3: Start Ratings Data Service
   cd ratings-data-service
   ./mvnw spring-boot:run
   
   # Terminal 4: Start Movie Catalog Service
   cd movie-catalog-service
   ./mvnw spring-boot:run

4. Verify services are registered

   Open http://localhost:8761 to see the Eureka dashboard.

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📡 API Endpoints

Movie Catalog Service (Port 8081)

Method	Endpoint	Description
GET	/catalog/{userId}	Get movie catalog for a user

Example Request:

curl http://localhost:8081/catalog/user123

Example Response:

[
  {
    "name": "The Dark Knight",
    "desc": "When the menace known as the Joker wreaks havoc...",
    "rating": 4
  },
  {
    "name": "Inception",
    "desc": "A thief who steals corporate secrets through...",
    "rating": 5
  }
]

Movie Info Service (Port 8082)

Method	Endpoint	Description
GET	/movies/{movieId}	Get movie details by TMDb ID

Ratings Data Service (Port 8083)

Method	Endpoint	Description
GET	/ratingsdata/{movieId}	Get rating for a movie
GET	/ratingsdata/users/{userId}	Get all ratings for a user

Hystrix Dashboard (Port 8081)

URL	Description
http://localhost:8081/hystrix	Hystrix Dashboard UI
http://localhost:8081/actuator/hystrix.stream	Metrics stream

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📚 Key Concepts

Service Discovery with Eureka

Services register themselves with the Eureka server, allowing other services to discover them by name instead of hardcoded URLs.

// Instead of: http://localhost:8082/movies/123
// Use service name: http://movie-info-service/movies/123
Movie movie = restTemplate.getForObject(
    "http://movie-info-service/movies/" + movieId,
    Movie.class
);

RestTemplate with Load Balancing

The @LoadBalanced annotation enables client-side load balancing:

@Bean
@LoadBalanced
public RestTemplate getRestTemplate() {
    return new RestTemplate();
}

Fault Tolerance with Hystrix

Circuit breakers prevent cascading failures by providing fallback responses:

@HystrixCommand(fallbackMethod = "getFallbackCatalogItem")
public CatalogItem getCatalogItem(Rating rating) {
    Movie movie = restTemplate.getForObject(
        "http://movie-info-service/movies/" + rating.getMovieId(),
        Movie.class
    );
    return new CatalogItem(movie.getName(), movie.getDescription(), rating.getRating());
}

// Fallback when movie-info-service is unavailable
public CatalogItem getFallbackCatalogItem(Rating rating) {
    return new CatalogItem("Movie name not found", "", rating.getRating());
}

---

⚙️ Configuration

Discovery Server

server.port=8761
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

Client Services

# Movie Catalog Service
spring.application.name=movie-catalog-service
server.port=8081
management.endpoints.web.exposure.include=hystrix.stream

# Movie Info Service
spring.application.name=movie-info-service
server.port=8082
api.key=YOUR_TMDB_API_KEY

# Ratings Data Service
spring.application.name=ratings-data-service
server.port=8083

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📊 Monitoring

Access the Hystrix Dashboard to monitor circuit breaker status:

1. Navigate to http://localhost:8081/hystrix
2. Enter the stream URL: http://localhost:8081/actuator/hystrix.stream
3. Click "Monitor Stream"

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🙏 Acknowledgments

• Java Brains - Tutorial inspiration
• Netflix OSS - Eureka & Hystrix
• The Movie Database (TMDb) - Movie data API