【Dubbo】Dubbo+ZK基础入门以及简单demo

参考文档：

官方文档：http://dubbo.io/

duboo中文：https://dubbo.gitbooks.io/dubbo-user-book/content/preface/background.html

 

1、是什么：

Dubbo |ˈdʌbəʊ| is a high-performance, java based RPC framework open-sourced by Alibaba. As in many RPC systems, dubbo is based around the idea of defining a service, specifying the methods that can be called remotely with their parameters and return types. On the server side, the server implements this interface and runs a dubbo server to handle client calls. On the client side, the client has a stub that provides the same methods as the server.

大体意思：Dubbo是阿里巴巴公司开源的一个高性能优秀的服务框架，使得应用可通过高性能的 RPC 实现服务的输出和输入功能，特点是：可以和Spring框架无缝集成。。。。

首先说说ZK是做什么的：

ZooKeeper是一个分布式的，开放源码的分布式应用程序协调服务，是Google的Chubby一个开源的实现，是Hadoop和Hbase的重要组件。它是一个为分布式应用提供一致性服务的软件，提供的功能包括：配置维护、域名服务、分布式同步、组服务等。

在dubbo中，dubbo的服务提供者会在zookeeper上面创建一个临时节点，表明自己的ip和端口，当消费者需要使用服务时，会先在zookeeper上面查询，找到服务提供者，做一些负载的选择（比如随机、轮流），然后按照这些信息，访问服务提供者。

ZK的安装：https://blog.csdn.net/the_fool_/article/details/80774500

2、官方文档中的解释：

         场景1、当服务越来越多时，服务 URL 配置管理变得非常困难，F5 硬件负载均衡器的单点压力也越来越大。

      此时需要一个服务注册中心，动态的注册和发现服务，使服务的位置透明。并通过在消费方获取服务提供方地址列表，实现软负载均衡和 Failover，降低对 F5 硬件负载均衡器的依赖，也能减少部分成本。

       场景2、当进一步发展，服务间依赖关系变得错踪复杂，甚至分不清哪个应用要在哪个应用之前启动，架构师都不能完整的描述应用的架构关系.

       这时 需要自动画出应用间的依赖关系图，以帮助架构师理清理关系。

       场景3、接着，服务的调用量越来越大，服务的容量问题就暴露出来，这个服务需要多少机器支撑？什么时候该加机器？

          为了解决这些问题，第一步，要将服务现在每天的调用量，响应时间，都统计出来，作为容量规划的参考指标。其次，要可以动态调整权重，在线上，将某台机器的权重一直加大，并在加大的过程中记录响应时间的变化，直到响应时间到达阀值，记录此时的访问量，再以此访问量乘以机器数反推总容量 。                                      

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3、架构（这个图刚看时不是很理解，但是结合组件来看还是很清晰的）：

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4、官方demo：

1、项目结构：

2、导包（pom.xml）：

<!--
 - Copyright 1999-2011 Alibaba Group.
 -
 - Licensed under the Apache License, Version 2.0 (the "License");
 - you may not use this file except in compliance with the License.
 - You may obtain a copy of the License at
 -
 -      http://www.apache.org/licenses/LICENSE-2.0
 -
 - Unless required by applicable law or agreed to in writing, software
 - distributed under the License is distributed on an "AS IS" BASIS,
 - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 - See the License for the specific language governing permissions and
 - limitations under the License.
-->
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.alibaba</groupId>
        <artifactId>dubbo-demo</artifactId>
        <version>2.5.8</version>
    </parent>
    <artifactId>dubbo-demo-provider</artifactId>
    <packaging>jar</packaging>
    <name>${project.artifactId}</name>
    <description>The demo provider module of dubbo project</description>
    <properties>
        <skip_maven_deploy>false</skip_maven_deploy>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo-demo-api</artifactId>
            <version>${project.parent.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>dubbo</artifactId>
            <version>${project.parent.version}</version>
        </dependency>
        <dependency>
            <groupId>com.101tec</groupId>
            <artifactId>zkclient</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.4</version>
        </dependency>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.0.35.Final</version>
        </dependency>
    </dependencies>
</project>

3、生产者：

public class DemoServiceImpl implements DemoService {

    public String sayHello(String name) {
        System.out.println("[" + new SimpleDateFormat("HH:mm:ss").format(new Date()) + "] Hello " + name + ", request from consumer: " + RpcContext.getContext().getRemoteAddress());
        return "Hello " + name + ", response form provider: " + RpcContext.getContext().getLocalAddress();
    }

}

提供服务：

public class Provider {

    public static void main(String[] args) throws Exception {
        //Prevent to get IPV6 address,this way only work in debug mode
        //But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-provider.xml"});
        context.start();

        System.in.read(); // press any key to exit
    }

}

配置文件dubbo-demo-provider.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!--
 - Copyright 1999-2011 Alibaba Group.
 -
 - Licensed under the Apache License, Version 2.0 (the "License");
 - you may not use this file except in compliance with the License.
 - You may obtain a copy of the License at
 -
 -      http://www.apache.org/licenses/LICENSE-2.0
 -
 - Unless required by applicable law or agreed to in writing, software
 - distributed under the License is distributed on an "AS IS" BASIS,
 - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 - See the License for the specific language governing permissions and
 - limitations under the License.
-->
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
	http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">

    <!-- 提供方应用信息，用于计算依赖关系 -->
    <dubbo:application name="demo-provider"/>

    <!-- 使用multicast广播注册中心暴露服务地址 -->
    <!--<dubbo:registry address="multicast://224.5.6.7:1234"/>-->
    <!-- 这是我自己的注册中心，安装启动即可，dubbo会自动创建节点。-->
    <dubbo:registry address="zookeeper://192.168.0.17:2181" />

    <!-- 用dubbo协议在20880端口暴露服务 -->
    <dubbo:protocol name="dubbo" port="20880"/>

    <!-- 和本地bean一样实现服务 -->
    <bean id="demoService" class="com.alibaba.dubbo.demo.provider.DemoServiceImpl"/>

    <!-- 声明需要暴露的服务接口 -->
    <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoService"/>

</beans>

4、消费者：

public class Consumer {

    public static void main(String[] args) {
        //Prevent to get IPV6 address,this way only work in debug mode
        //But you can pass use -Djava.net.preferIPv4Stack=true,then it work well whether in debug mode or not
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        DemoService demoService = (DemoService) context.getBean("demoService"); // get remote service proxy

        while (true) {
            try {
                Thread.sleep(1000);
                String hello = demoService.sayHello("world"); // call remote method
                System.out.println(hello); // get result

            } catch (Throwable throwable) {
                throwable.printStackTrace();
            }

        }

    }
}

配置文件dubbo-demo-consumer.xml：

<?xml version="1.0" encoding="UTF-8"?>
<!--
 - Copyright 1999-2011 Alibaba Group.
 -
 - Licensed under the Apache License, Version 2.0 (the "License");
 - you may not use this file except in compliance with the License.
 - You may obtain a copy of the License at
 -
 -      http://www.apache.org/licenses/LICENSE-2.0
 -
 - Unless required by applicable law or agreed to in writing, software
 - distributed under the License is distributed on an "AS IS" BASIS,
 - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 - See the License for the specific language governing permissions and
 - limitations under the License.
-->
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
	http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">

    <!-- 消费方应用名，用于计算依赖关系，不是匹配条件，不要与提供方一样 -->
    <dubbo:application name="demo-consumer"/>

    <!-- 使用multicast广播注册中心暴露发现服务地址 -->
    <!--<dubbo:registry address="multicast://224.5.6.7:1234"/>-->
    <!-- 去我自己安装的注册中心索取服务 -->
    <dubbo:registry address="zookeeper://192.168.0.17:2181" />
    <!-- 生成远程服务代理，可以和本地bean一样使用demoService -->
    <dubbo:reference id="demoService" check="false" interface="com.alibaba.dubbo.demo.DemoService"/>

</beans>

与cloud的区别？如何选择？

个人观点：博主了解的并不深入，个人觉得springcloud更加全面，使用起来更顺手一点。等熟练用过后会考虑做个对比。