Microservice Setup - ganmath/learners GitHub Wiki

1. Introduction
   • Overview
   • Objectives
2. Project Setup and Configuration
   • Tools and Technologies
   • Maven Configuration
   • Spring Boot Setup
3. Microservices Architecture Diagram
   • Overview of Services
4. Microservices Project Structure
   • Common Libraries
   • Service-specific Modules
5. Service Implementation
   • Order Processing Service
   • Product Catalog Service
   • Customer Service
   • Configuration Service
   • Discovery Service
6. Microservices Internal Communication
   • REST API Communication
   • Examples of RESTful Calls
7. Conclusion
   • Summary
   • Next Steps

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This document provides a detailed guide for developing a microservices architecture using Spring Boot and Maven, emphasizing scalable and maintainable services communicating over REST APIs.

• Implement several interconnected microservices.
• Ensure services can discover each other and communicate efficiently.
• Utilize Spring Boot and Spring Cloud for development and deployment.

• Java: Primary programming language.
• Spring Boot: Framework for creating stand-alone, production-grade Spring-based Applications.
• Maven: Dependency management and project build tool.
• Eureka Server: For service discovery.
• Spring Cloud Config: For external configuration management.

• Parent POM setup:

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.5.0</version>
  </parent>

• Dependencies:

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- Additional dependencies -->
  </dependencies>

• Application properties:

  server.port=8080
  eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka

The diagram illustrates the interconnected nature of the services, emphasizing their dependencies and the flow of information.

• Utility Library: Shared logic and common functionalities.

• Each service is structured as a Maven submodule:

  myapp/
  ├── pom.xml
  ├── order-service/
  │   ├── src/
  │   ├── pom.xml
  ├── catalog-service/
  │   ├── src/
  │   ├── pom.xml
  ├── customer-service/
  │   ├── src/
  │   ├── pom.xml
  

• Application Class:

  @SpringBootApplication
  @EnableEurekaClient
  public class OrderServiceApplication {
    public static void main(String[] args) {
      SpringApplication.run(OrderServiceApplication.class, args);
    }
  }

• Controller Example:

  @RestController
  @RequestMapping("/products")
  public class ProductController {
    @GetMapping("/{id}")
    public ResponseEntity<Product> getProductById(@PathVariable Long id) {
      // Logic to fetch product
      return ResponseEntity.ok(new Product(id, "Sample Product"));
    }
  }

• Customer Retrieval:

  @GetMapping("/customer/{id}")
  public Customer getCustomer(@PathVariable String id) {
    return new Customer(id, "John Doe");
  }

• Spring Cloud Config:

  @SpringBootApplication
  @EnableConfigServer
  public class ConfigServiceApplication {
    public static void main(String[] args) {
      SpringApplication.run(ConfigServiceApplication.class, args);
    }
  }

• Configuration Example:

  # Application-specific overrides
  order-service.datasource.url=jdbc:mysql://localhost:3306/orderdb
  product-service.datasource.url=jdbc:mysql://localhost:3306/productdb
  customer-service.datasource.url=jdbc:mysql://localhost:3306/customerdb

• Eureka Server Setup:

  @SpringBootApplication
  @EnableEurekaServer
  public class DiscoveryServiceApplication {
    public static void main(String[] args) {
      SpringApplication.run(DiscoveryServiceApplication.class, args);
    }
  }
  ``

`

• Inter-service REST Calls:
  • Feign Client Example:

    @FeignClient(name = "product-service")
    public interface ProductServiceClient {
      @GetMapping("/products/{id}")
      Product getProductById(@PathVariable("id") Long id);
    }

  • Configuration of URLs: URLs or names of the target microservices are configured in the application properties under eureka.client.service-url.defaultZone which points to the Eureka Server.

• Product information is retrieved by the Order Processing Service to check stock before processing an order.

The document outlines a structured approach to building a microservices architecture using Spring Boot, focusing on service setup, configuration, and communication.

• Further develop individual service features.
• Implement advanced security measures and monitoring.

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Note: The code snippets provided are simplified. In real-world applications, you should handle exceptions, security, and data management more robustly.