dubbo(一)

1.概述

　　dubbo是一个分布式的rpc框架，提供多种注册中心，调用方式和序列化方式。

2.应用

　　

package com.alibaba.dubbo.demo.impl;

import java.io.IOException;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {
    public static void main(String[] args) throws IOException {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("provider.xml");
        System.err.println(context.getDisplayName() + ": here");
        context.start();
        System.err.println("服务已经启动...");
        System.in.read();
    }
}

<?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://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://code.alibabatech.com/schema/dubbo
       http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <!--定义了提供方应用信息，用于计算依赖关系；在 dubbo-admin 或 dubbo-monitor 会显示这个名字，方便辨识-->
    <dubbo:application name="demotest-provider" owner="programmer" organization="dubbox"/>
    <!--使用 zookeeper 注册中心暴露服务，注意要先开启 zookeeper-->
    <dubbo:registry address="zookeeper://localhost:2181"/>
    <!-- 用dubbo协议在20880端口暴露服务 -->
    <dubbo:protocol name="dubbo" port="20880" />
    <!--使用 dubbo 协议实现定义好的 api.PermissionService 接口-->
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService" protocol="dubbo" />
    <!--具体实现该接口的 bean-->
    <bean id="demoService" class="com.alibaba.dubbo.demo.impl.DemoServiceImpl"/>
</beans>

客户端

　　

package com.alibaba.dubbo.consumer;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.alibaba.dubbo.demo.DemoService;

public class Consumer {
    public static void main(String[] args) {
        //测试常规服务
        ClassPathXmlApplicationContext context =
                new ClassPathXmlApplicationContext("consumer.xml");
        context.start();
        System.err.println("consumer start");
        DemoService demoService = context.getBean(DemoService.class);
        System.err.println("consumer");
        System.out.println(demoService.getPermissions(1L));
    }
}

<?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://code.alibabatech.com/schema/dubbo"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
    <dubbo:application name="demotest-consumer" owner="programmer" organization="dubbox"/>
    <dubbo:registry address="zookeeper://localhost:2181"/>
    <dubbo:reference id="permissionService" interface="com.alibaba.dubbo.demo.DemoService"/>
</beans>

 

3.原理

　　

 

　　以上为基本原理图，消费端通过注册中心来确定有多少个服务端，消费端与每个服务端维持一个长连接，当有调用时会根据负载均衡策略来选择向那个服务端发送请求。