Dubbo简介

Dubbo是阿里巴巴开源的一款Java RPC框架

• 一款分布式服务框架

• 高性能和透明化的RPC远程服务调用方案

• SOA服务治理方案

核心功能

智能容错和负载均衡

服务注册和发现

面向接口的远程方法调用

角色

Provider（生产者）：暴露服务的服务提供者

Container：服务运行的容器

Consumer（消费者）：调用远程服务的消费者

Registry：服务注册和发现的注册中心

Minitor：统计服务调用次数和时间的监控中心

架构

1、单体应用

2、垂直应用

3、SOA 架构

4、微服务架构

dubbo+zookeeper

zookeeper是dubbo的注册中心，可以用于dubbo作负载均衡。

1、安装zookeeper

https://zookeeper.apache.org/releases.html

2、安装dubbo

https://github.com/apache/dubbo

配置 依赖：

<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-dubbo</artifactId>
</dependency>
<dependency>
<groupId>com.bx.dubbo</groupId>
<version>1.0-SNAPSHOT</version>
<artifactId>spring-cloud-dubbo-sample-api</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

多个服务端口使用一个通讯协议

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">
    <dubbo:application name="world"  />
    <dubbo:registry id="registry" address="" username="admin" password="hello1234" />
    <dubbo:protocol name="dubbo" port="20880" />
    <!-- Use dubbo protocol to expose the service -->
    <dubbo:service interface="com.alibaba.hello.api.HelloService" version="1.0.0" ref="helloService" />
    <dubbo:service interface="com.alibaba.hello.api.DemoService" version="1.0.0" ref="demoService" />
</beans>

LoadBalance算法

@SPI(RandomLoadBalance.NAME)
public interface LoadBalance {
    @Adaptive("loadbalance")
    <T> Invoker<T> select(List<Invoker<T>> invokers, URL url, Invocation invocation) throws RpcException;
 
}
 

随机均衡算法

public class RandomLoadBalance extends AbstractLoadBalance {
 
    public static final String NAME = "random";
    private final Random random = new Random();
    @Override
    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
        //provider 的数量
        int length = invokers.size(); 
        int totalWeight = 0; 
        boolean sameWeight = true; 
        for (int i = 0; i < length; i++) {
            int weight = getWeight(invokers.get(i), invocation);
            totalWeight += weight; 
            if (sameWeight && i > 0
                    && weight != getWeight(invokers.get(i - 1), invocation)) {
                sameWeight = false;
            }
        }
        if (totalWeight > 0 && !sameWeight) {
            int offset = random.nextInt(totalWeight);

            for (int i = 0; i < length; i++) {
                offset -= getWeight(invokers.get(i), invocation);
                if (offset < 0) {
                    return invokers.get(i);
                }
            }
        }
        return invokers.get(random.nextInt(length));
    }
}