SpringCloudAlibaba--Nacos作为服务注册中心、各种注册中心对比、Nacos的AP和CP模式切换

亦凉 2021-08-27 17:42 576阅读 0赞

### 基于Nacos的服务提供者 ###

**创建cloudalibaba-provider-payment9001模拟支付模块：**  
依赖：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <parent>
            <artifactId>cloud2020</artifactId>
            <groupId>pers.zhang.springcloud</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>cloudalibaba-provider-payment9001</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

配置：application.yml

server:
      port: 9001
    
    spring:
      application:
        name: nacos-payment-provider
      cloud:
        nacos:
          discovery:
            server-addr: localhost:8848 #配置Nacos地址
    
    management:
      endpoints:
        web:
          exposure:
            include: '*'

Controller：

@RestController
    public class PaymentController { 
    
        @Value("${server.port}")
        String serverPort;
    
        @GetMapping("/payment/nacos/{id}")
        public String getPayment(@PathVariable("id") Long id){ 
            return "nacos registry, serverPort:" + serverPort + "\t id" + id;
        }
    }

启动类：

@SpringBootApplication
    @EnableDiscoveryClient
    public class PaymentMain9001 { 
        public static void main(String[] args) { 
            SpringApplication.run(PaymentMain9001.class, args);
        }
    }

测试：启动Nacos，启动9001微服务：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 1]

### 基于Nacos的服务消费者 ###

首先，根据上文的9001微服务再创建一个9002微服务。

**新建cloudalibaba-consumer-nacos-order83模拟订单模块**

依赖：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <parent>
            <artifactId>cloud2020</artifactId>
            <groupId>pers.zhang.springcloud</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>cloudalibaba-consumer-nacos-order83</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
            </dependency>
            
            <dependency>
                <groupId>pers.zhang.springcloud</groupId>
                <artifactId>cloud-api-commons</artifactId>
                <version>${project.version}</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

配置：application.yml

server:
      port: 83
    
    spring:
      application:
        name: nacos-order-consumer
      cloud:
        nacos:
          discovery:
            server-addr: localhost:8848
    
    #消费者将要去访问的微服务名称（注册成功进nacos的微服务提供者）
    service-url:
      nacos-user-service: http://nacos-payment-provider

@Configuration
    public class ApplicationContextConfig { 
    
        @Bean
        @LoadBalanced
        public RestTemplate getRestTemplate() { 
            return new RestTemplate();
        }
    }

Controller：

@RestController
    @Slf4j
    public class OrderNacosController { 
    
        @Resource
        RestTemplate restTemplate;
    
        @Value("${service-url.nacos-user-service}")
        String serverURL;
    
        @GetMapping("/consumer/payment/nacos/{id}")
        public String paymentInfo(@PathVariable("id") Long id) { 
            String result = restTemplate.getForObject(serverURL + "/payment/nacos/" + id, String.class);
            return result;
        }
    }

启动类：

@SpringBootApplication
    @EnableDiscoveryClient
    public class OrderNacosMain83 { 
        public static void main(String[] args) { 
            SpringApplication.run(OrderNacosMain83.class, args);
        }
    }

### 测试 ###

启动Nacos，启动9001和9002，以及83端口微服务：

查看8848控制台，注册成功。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 2]  
访问：`localhost:83/consumer/payment/nacos/222`，轮询负载OK。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 4]  
Nacos集成了Ribbon，自带负载均衡。

### 各种注册中心对比 ###

**Nacos全景图：**  
![在这里插入图片描述][format_png]

**Nacos与CAP：**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 5]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 6]

### Nacos的AP和CP模式切换 ###

*  C是所有节点在同一时间看到的数据是一致的；
 *  A的定义是所有请求都会收到响应。

**何时选用哪种模式？**

一般来说，如果不需要存储服务级别的信息且服务实例是通过nacos-client注册，并能够保持心跳上报，那么就可以选择AP模式。当前主流的服务如Spring Cloud 和 Dubbo服务，都适用于AP模式，AP模式为了服务的可能性而减弱了一致性，因此`AP模式下只支持注册临时实例。`

如果需要在服务级别编辑或者存储配置信息，那么CP是必须的，K8S服务和DNS服务则适用于CP模式。CP模式下支持注册持久化实例，此时则是以Raft协议为集群运行模式，该模式下注册实例之前`必须先注册服务，如果服务不存在，则会返回错误。`

curl -X PUT `$NACOS_SERVER:8848/nacos/v1/ns/operator/switches?entry=serverMode&value=CP'

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[format_png]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly90aW1nc2EuYmFpZHUuY29tL3RpbWc_aW1hZ2UmcXVhbGl0eT04MCZzaXplPWI5OTk5XzEwMDAwJnNlYz0xNTg0NzMyMzU3NzAxJmRpPTY0NzI4ZGRmZTkzMWExZDMxYzdmMjFmZDc1OTg3ZjNiJmltZ3R5cGU9MCZzcmM9aHR0cCUzQSUyRiUyRjViMDk4OGU1OTUyMjUuY2RuLnNvaHVjcy5jb20lMkZpbWFnZXMlMkYyMDE4MDcwNSUyRjZiMTEwMzEzMTJhMjRiY2ViMzQzZGE4ODBkMmU1YjM3LnBuZw?x-oss-process=image/format,png
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