springcloud-ribbon Load Balancing

I. Introduction

After several series of cloud, I think we have a solid foundation for subsequent learning will be a lot easier, just to see if there are eureka reader needs basic knowledge, or knowledge seekers access to the cloud series of columns; this The main article explains how to use the ribbon implement web service client calls, ribbon default load balancing algorithm!

About two ribbon

ribbon is a client load balancer that can integrate different protocols tools for web service API calls;

The main features are as follows:

1. Provide pluggable load balancing
2. Integration Service discovery
3. Fault elastic recovery
4. cloud support
5. Integrated load balancing client load

The core project as follows:

ribbon-core: integration with other modules to achieve load balancing

ribbon-eureka: eureka client-based load balancing

ribbon-httpclient: JSR-311 includes a loading implement load balancing REST

Three eureka-client

Created in the previous Project eureka-client packet controller, and providing a representation of an interface layer, as follows, and then start the eureka-client Example 2, respectively, port 8090, port 8091;

/**
 * @Author lsc
 * <p> 知识追寻者，ribbon provider the restful api</p>
 */
@RestController
public class RibbonProvidderController {


    @GetMapping("zszxz/ribbon")
    public String testRibbon(){
        return "hell i am zszxz";
    }
}

Four ribbon-client

4.1 pom.xml

In the lower parent project new module is added ribbon-client; original start-web dependence has been introduced in the parent project, so that the ribbon does not introduce the module dependency again;

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
    </dependencies>

4.2 config

RestTemplate used for client calls, it needs to be configured, and the method for adding annotation @LoadBalanced opening ribbon represents the load balancing;

/**
 * @Author lsc
 * <p> ribbon-restTemplate配置 </p>
 */
@Configuration
public class RibbonConfig {

    @Bean
    @LoadBalanced//表示用于负载均衡
    RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

4.3 service

Create a service class, and use restTemplate conduct HTTP API calls; note the point here is not to use the ip port, but directly using the application name of the service eureka-client;

/**
 * @Author lsc
 * <p> </p>
 */
@Service
public class RibbonService {

    @Autowired
    RestTemplate restTemplate;


    public String testRibbon(){
        return restTemplate.getForObject("http://eureka-client/zszxz/ribbon",String.class);
    }
}

4.4 controller

Create a presentation layer classes for browser access;

/**
 * @Author lsc
 * <p> </p>
 */
@RestController
public class RibbonController {

    @Autowired
    RibbonService ribbonService;

    @GetMapping("ribbon/test")
    public String testRibbon(){
        return ribbonService.testRibbon();
    }
}    

4.5 ribbon startup class

The ribbon is started as a client-based terminal eureka @EnableEurekaClient it necessary to add annotations;

/**
 * @Author lsc
 * <p>知识追寻者 ribbon启动类 </p>
 */
@SpringBootApplication
@EnableEurekaClient
public class RibbonApp {

    public static void main(String[] args) {
        SpringApplication.run(RibbonApp.class,args);
    }
}

4.6 application.yml

application.yml configurations using port 8092, registered address service are peer1, peer2, peer3;

server:
  port: 8092

spring:
  application:
    name: eureka-ribbon # 应用名称

eureka:
  client:
    service-url:
      # 服务注册地址
      defaultZone: http://peer1:10081/eureka/,http://peer2:10082/eureka/,http://peer3:10083/eureka/

4.7 Start Project

Each start client, server; FIG follows

4.8 browser to access the results

Browser results are as follows, that we use restTemplate combine ribbon achieved through HTTP API calls from eureka-clinet module in the eureka-ribbon;

Five ribbon default load balancing

LoadBalancerClient is a core class ribbon, which can be obtained ribbon provides an example of information load balancing; adding the controller layer method ribbon-client module, the method body is obtained instance port and host; facilitate our analysis ribbon load balancing algorithm ;

    @Autowired
    LoadBalancerClient loadBalanced;

    @GetMapping("ribbon")
    public String ribbon(){
        ServiceInstance choose = loadBalanced.choose("eureka-client");
        String s = "host is :" + choose.getHost() + "  port is :" + choose.getPort();
        System.out.println(s);
        return s;
    }

Restart ribbon-client project, accessed using a browser, the console output is as follows, respectively called 8090,8091 two examples eureka-client API, explained ribbon default load-balancing mechanism is a polling algorithm;

host is :peer1  port is :8091
host is :peer1  port is :8090
host is :peer1  port is :8091
host is :peer1  port is :8090
host is :peer1  port is :8091
host is :peer1  port is :8090
host is :peer1  port is :8091
host is :peer1  port is :8090