Service routing and load balancing in Spring Cloud

Service routing and load balancing in Spring Cloud

• 1. Service Routing
• • 1. Service Discovery
  • 2. Service Registration
  • 3. Service Consumption
  • 4. Service provision
  • 5. Service routing implementation
• 2. Load balancing
• • 1. The concept of load balancing
  • 2. Load balancing algorithm
  • 3. Load balancing implementation
  • 4. Load balancing strategy
  • 5. Use Spring Cloud to achieve load balancing
• 3. Integration of service routing and load balancing
• • 1. Integration background
  • 2. Integrated architecture
  • 3. Integration implementation
  • • ribbon
    • Zuul
  • 4. Integration testing and optimization
  • 5. Analysis of integrated service routing and load balancing effects
• 4. Summary and review
• • 1. Application scenarios of service routing and load balancing
  • 2. How does the Spring Cloud service provider maximize the use of service routing and load balancing

1. Service routing

This article will discuss the service routing issues in Spring Cloud, including service discovery, service registration, service consumption, service provision and service routing implementation.

1. Service discovery

In the microservice architecture, it is often necessary to call the service according to the service name. At this point service discovery becomes very important. In Spring Cloud, you can use Eureka to implement service discovery by introducing spring-cloud-starter-netflix-eureka-server dependencies in the pom.xml file.

2. Service Registration

Similar to service discovery, service registration is also the basis of microservice architecture. In Spring Cloud, you can write the following code to implement service registration:

@SpringBootApplication
@EnableDiscoveryClient
public class DemoApplication {<!-- -->
    public static void main(String[] args) {<!-- -->
        SpringApplication.run(DemoApplication.class, args);
    }
}

The @EnableDiscoveryClient annotation indicates that the service registration center is enabled.

3. Service consumption

Service consumption refers to calling the provider’s service through the service name in the microservice architecture. In Spring Cloud, service consumption can be realized through RestTemplate or FeignClient. Here is an example using FeignClient:

@FeignClient(name = "demo-service")
public interface DemoService {<!-- -->
    @RequestMapping(value = "/hello", method = RequestMethod. GET)
    String hello();
}

4. Service provision

The service provider is the party that provides the service and is responsible for providing the actual service. Similar to service consumption, you can use the @RestController annotation to write a service provider in Spring Cloud:

@RestController
public class DemoController {<!-- -->
    @RequestMapping(value = "/hello", method = RequestMethod. GET)
    public String hello() {<!-- -->
        return "Hello World";
    }
}

5. Service routing implementation

In a microservice architecture, service routing is the key to passing requests from clients to service providers. In Spring Cloud, Zuul can be used to implement service routing. Here is an example using Zuul:

@SpringBootApplication
@EnableZuulProxy
public class GatewayApplication {<!-- -->
    public static void main(String[] args) {<!-- -->
        SpringApplication.run(GatewayApplication.class, args);
    }
}

The @EnableZuulProxy annotation indicates that the Zuul proxy function is enabled

2. Load balancing

1. The concept of load balancing

Load balancing refers to the process of evenly distributing tasks to different computers in the service cluster, so as to achieve the purpose of improving system performance and reliability. After one computer finishes processing a task, it automatically transfers the task to other idle computers to continue processing. This is the basic principle of load balancing.

2. Load balancing algorithm

There are mainly the following types of load balancing algorithms:

• Round Robin: Round Robin selects servers for access, and assigns requests to each server in turn.
• Random: Randomly select a server for access.
• Least Connections: Dynamically select the server with the least number of current connections for access.
• IP Hash (IP Hash): Through the Hash operation on the IP address of the access client, a number is obtained as a subscript, and the subscript is used to select a server for access.

3. Load balancing implementation

Spring Cloud provides a load balancer–LoadBalancerClient, which can be used to access multiple instances in the service cluster and has the function of load balancing.

Code example:

@Autowired
private LoadBalancerClient loadBalancer;

public void doSomething() {<!-- -->
    ServiceInstance instance = loadBalancer. choose("service-name");
    String baseUrl = "http://" + instance.getHost() + ":" + instance.getPort();
    
    // According to baseUrl, use tools such as RestTemplate to send requests and process responses
}

In the above code, the choose() method of LoadBalancerClient is used to select an instance from the service cluster with the service name service-name. Then, assemble the base URL address of the instance for sending HTTP requests.

4. Load balancing strategy

Spring Cloud provides a variety of load balancing strategies that can be selected according to the actual situation, for example:

• RoundRobinRule: polling strategy;
• RandomRule: random strategy;
• RetryRule: retry strategy;
• WeightedResponseTimeRule: Response time weighting strategy.

You can use the corresponding load balancing strategy by specifying in the configuration file:

ribbon:
  eureka:
    enabled: true
  client:
    name: service-name
    loadbalancer:
      # use polling strategy
      type: RoundRobin

5. Using Spring Cloud to achieve load balancing

To achieve load balancing in Spring Cloud, the following steps need to be completed:

1. Build a service provider cluster to register and discover through Eureka
2. Introduce spring-cloud-starter-netflix-ribbon dependency in service consumer to enable Ribbon load balancing function
3. Use LoadBalancerClient in the service consumer to access multiple instances in the service provider cluster

3. Integration of service routing and load balancing

1. Integration background

The number of service instances in the microservice architecture changes dynamically. The service caller needs to obtain a list of service instances through the service registry, and select one of the reachable instances to call. This involves the issues of service routing and load balancing. And Spring Cloud provides a complete solution to solve this problem.

2. Integrated Architecture

The integrated architecture of Spring Cloud’s service routing and load balancing is as follows:

• Service Consumer: the application that invokes the service
• Service Provider: An application that provides a service
• Service Registry: maintain service instance information and its metadata information, and provide service discovery function
• Service Gateway: As a unified entrance for traffic, it requires the ability to load balance and route and forward

3. Integration implementation

Spring Cloud provides Ribbon and Zuul two ways to realize the integration of service routing and load balancing

Ribbon

Ribbon is a client-side load balancer provided by Spring Cloud, which is integrated as a client on the service consumer side. By embedding a load balancing algorithm on the service consumer side, the client load balancing is realized.

When using the Ribbon, the service consumer will obtain a list of available service instances from the service registry, and select an instance to request the service provider through the load balancing algorithm. Ribbon supports a variety of load balancing algorithms, and can customize the load balancing strategy.

Zuul

Zuul is a gateway server provided by Spring Cloud, which is mainly used for routing and filtering. Zuul can forward traffic to each service instance on the backend to achieve dynamic routing and load balancing for microservices.

When using Zuul, the service consumer sends the request to Zuul as a unified entrance, and Zuul forwards the request to the specific backend service according to the request URL. Zuul supports routing based on URL path, Cookie, Header and other methods.

4. Integration testing and optimization

Need to test and optimize after the integration is complete

The following aspects need to be paid attention to in the integration of service routing and load balancing:

1. Selection and configuration of load balancing strategies: Different load balancing strategies will have an impact on performance, and an appropriate load balancing strategy needs to be selected according to the actual situation.
2. Optimization of load balancing algorithm: For high-concurrency scenarios, it is necessary to tune the load balancing algorithm in a targeted manner to improve the response speed and throughput of the service.
3. Service routing test: It is necessary to conduct a comprehensive test on service routing to ensure that it performs well in various scenarios.

5. Analysis of integrated service routing and load balancing effects

After integration, it is necessary to analyze the effects of service routing and load balancing. It can mainly start from the following aspects:

1. Response speed and throughput: Confirm that service routing and load balancing can improve service response speed and throughput.
2. Failover: test the load balancing strategy and algorithm under failure conditions, and verify the correctness and speed of failover.
3. Advantages and disadvantages of load balancing strategies and algorithms: analyze and compare the advantages and disadvantages of different load balancing strategies and algorithms, and select the optimal configuration scheme.

4. Summary review

1. Application scenarios of service routing and load balancing

• The large number of service instances in the microservice architecture requires service routing and load balancing control.
• Service discovery is performed through the service registry, and the list of service instances is automatically maintained.
• The balanced distribution of service calls is carried out through the load balancing algorithm, which improves the system throughput and performance stability.

2. How Spring Cloud service providers maximize the use of service routing and load balancing

• The service provider needs to register it with the service registry to realize automatic discovery of service instances.
• Ribbon’s load balancing strategy and algorithm can be configured for specific services to optimize service call response time and throughput.
• Use the Zuul gateway server for unified entry management to achieve unified routing forwarding and load balancing.