Service Architecture

Monolithic Architecture

All business functions are integrated into a single project, packaged as one unit for deployment.

Pros: Simple architecture, low deployment cost. Good for small projects.

Cons: High coupling. Poor scalability.

Distributed Architecture

Split the system based on business functions. Each module is developed as an independent project, called a “service.”

Pros: Reduced coupling, easier to upgrade and scale.

Cons: Complex architecture, high difficulty. Suitable for large-scale internet projects.

Microservices

Microservices is a well-designed distributed architecture pattern. Key characteristics:

• Single Responsibility : Fine-grained service splitting. Each service corresponds to a unique business capability to avoid redundant development.
• Service-Oriented: Services expose business interfaces to the outside.
• Autonomous: Independent teams, tech stacks, data, and deployment.
• Strong Isolation: Implement isolation, fault tolerance, and fallbacks for service calls to prevent cascading failures.

Microservice Technologies

Implementing a microservice solution requires a technical framework. Common ones include:

Microservices should be split according to business modules:

• Single Responsibility: Don’t duplicate the same business logic in different services.
• Data Independence: Do not directly access other services’ databases.
• Service-Oriented: Expose your business logic as interfaces for other services to call.

SpringCloud

SpringCloud is currently the most widely used microservice framework. It integrates various microservice components and implements auto-configuration based on SpringBoot.

Official Website: https://spring.io/projects/spring-cloud/

• Service Registration & Discovery: Eureka, Nacos, Consul
• Unified Configuration Management: SpringCloudConfig, Nacos
• Remote Service Calls: OpenFeign, Dubbo
• Unified Gateway Routing: SpringCloudGateway, Zuul
• Distributed Tracing: Zipkin, Sleuth
• Flow Control, Fallback, & Protection: Hystix, Sentinel

Microservice Calls

Requirement: When querying an order by ID, return the associated user information as well.

Register RestTemplate

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@Bean
public RestTemplate restTemplate(){
    return new RestTemplate();
}

Remote Service Call with RestTemplate

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@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private RestTemplate restTemplate;

    public Order queryOrderById(Long orderId) {
        // 1. Query the order
        Order order = orderMapper.findById(orderId);
        // 2. Query the user
        String url = "http://localhost:8081/user/" + order.getUserId();
        // RestTemplate GET method
        User user = restTemplate.getForObject(url, User.class);
        // 3. Encapsulate user info
        order.setUser(user);
        // 4. Return
        return order;
    }
}