Registration and discovery services SpringCloud01--

Registration and discovery services SpringCloud01--

A micro-service registration and discovery

We micro-services, often there are service providers, service consumers and service registration centers. Before we learn Zookeeper is a registered center. But in the official SpringCloud, it is not recommended to use ZK as a registration center, we tend to use eureka

Service providers, service consumers, the registry was a triangle

1. Service providers will be registered to the service center

2. Service consumers through the registry to find services

3. Find a service call

4. service consumers and service registration centers to maintain a heartbeat connection, once the address of the service provider is changed, the registry will notify the customer service

Second, the registry eureka

SpringCloud offers a variety of registry support, eureka, zk, etc., officially recommended eureka

科普：什么是Eureka？
Eureka是Netfix开源的服务发现组件，本身是一个基于Rest的服务。包含Server和Client两部分。SpringCloud将其集成在子项目Spring Cloud Netflix中，从而实现微服务的注册和发现。

2.1. Writing Eureka Server

2.1.1 Create a new Spring Starter, introduced eureka server

2.1.2. Creating a application.yml, start class @EnableEurekaServer

server:
  port: 1111 #服务端口
 
eureka:
  client:
    register-with-eureka: false #是否将自己注册到Eureka服务中，自己本来就是服务无需注册
    fetch-registry: false #是否从Eureka中获取注册信息
    service-url: # Eureka客户端与Eureka服务端交互地址
      defaultZone: http://localhost:${server.port}/eureka/

2.1.3. Create a new Spring Starter, import eureka, write a service

2.1.4. Creating a application.yml, start class @EnableDiscoveryClient, go to the registration center to register the above discovery

server:
  port: 8081 
  
spring:
  application:
    name: microservice-item
    
eureka:
  client:
    register-with-eureka: true
    fetch-registry: true #是否从eureka中获取注册信息，默认true
    service-url:
      defaultZone: http://localhost:1111/eureka/

2.1.5. Writing Services (key codes)

@Service
public class ItemService {
    
    @Autowired
    private RestTemplate restTemplate;
    
    @Autowired
    private DiscoveryClient discoveryClient;
    
    /**
     * 商品微服务进行查询
     * @param id
     * @return
     */
    public Item queryItemById(Long id) {
        List<ServiceInstance> instances = discoveryClient.getInstances("MICROSERVICE-ITEM");
        ServiceInstance serviceInstance = instances.get(0);
        String url="http://"+serviceInstance.getHost()+":"+serviceInstance.getPort()+"/item/"+id;
        return restTemplate.getForObject(url, Item.class);
    }
}

2.2 write. Eruka-client

2.2.1. Create a eruka-client, and discovery component added eruka web package

2.2.2. Writing the configuration file application.yml

#服务端口
server:
  port: 8888

#应用名称及验证账号
spring:
  application:
    name: server-text

#注册中心
eureka:
  #  server:
  #    enable-self-preservation: false       #关闭保护机制
  #    eviction-interval-timer-in-ms: 2000   #剔除失效服务间隔,单位毫秒
  client:
    register-with-eureka: true
    fetch-registry: true
    #设置服务注册中心的URL
    service-url:
      defaultZone: http://root:root@eureka-7901:7901/eureka/
  instance:
    hostname: server-text

2.2.3. Adding startup class notes

@EnableEurekaClient

2.2.4. After starting the cluster starts normally found