• Service registration: In the framework of service governance, a registry is built, and each service unit registers with the registry the details of its services.And form a list of services in the registry. The service registry needs to monitor the availability of services in the list in a heartbeat way. If not, it needs to exclude the unavailable services from the list.
• Service discovery: A service invokes a service consulting service with the service registry and obtains a list of instances of all services to access a specific service instance.

• Service registration: Save information about service providers and service callers
• Service subscription: A service caller subscribes to information from a service provider, and the registry pushes information from the provider to the subscriber

• Configuring subscriptions: Service providers and service callers subscribe to microservice-related configurations
• Configuration Download: Actively push configuration to service providers and service callers

• Detect the health of service providers and perform service culling if exceptions are found

• Zookeeper

• Eureka

• Consul

 Double-click startup.cmd to start nacos

Step 3: Visit nacos

 3.3.2 Register commodity microservices with nacos

3.3.3 Register order microservices with nacos

 

6 Then the call succeeds by accessing the consumer service validation

3.4 Implement load balancing for service calls

3.4.1 What is load balancing

In a microservice invocation relationship, we generally choose client load balancing, that is, when one side of a service invocation decides which provider the service is to be executed by.

3.4.2 Customize Load Balancing

 2 View microservice startup via nacos

 You can also view service details

 3 Modify the shop-order code to achieve load balancing (we use random numbers to achieve load balancing ourselves)

package com.itheima.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.alibaba.fastjson.JSON;
import com.itheima.entity.Order;
import com.itheima.entity.Product;
import com.itheima.service.OrderService;

import java.util.List;
import java.util.Random;

@RestController
@Slf4j
public class OrderController {

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private DiscoveryClient discoveryClient;

    @Autowired
    private OrderService orderService;

    //Ready to buy one item
    @GetMapping("/order/prod/{pid}")
    public Order order(@PathVariable("pid") Integer pid) {

        // Get service address from nacos
        // Custom Rules Implement Random Selection Service
        List<ServiceInstance> instances = discoveryClient.getInstances("service-product");

        int index = new Random().nextInt(instances.size());
        ServiceInstance serviceInstance = instances.get(index);

        String url = serviceInstance.getHost() + ":" + serviceInstance.getPort();
        log.info(">>from nacos The microservice address obtained in is:" + url);

        //Calling commodity microservices through restTemplate
        Product product = restTemplate.getForObject(
                "http://" + url +"/product/" + pid, Product.class);

        log.info(">>Commodity Information,Query Results:" + JSON.toJSONString(product));

        Order order = new Order();
        order.setUid(1);
        order.setUsername("Test User");
        order.setPid(product.getPid());
        order.setPname(product.getPname());
        order.setPprice(product.getPprice());
        order.setNumber(1);

        orderService.save(order);

        return order;
    }

}

3.4.3 Load Balancing Based on Ribbon

 We can adjust Ribbon's load balancing strategy by modifying the configuration as follows

service-product: # Name of the provider invoked 
  ribbon: 
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

3.5 Feign-based implementation of service calls

3.5.1 What is Feign

2 Add Fegin's comment on the main class