一、前言
Dubbo 作为SOA服务化治理方案的核心框架，用于提高业务逻辑的复用、整合、集中管理，具有极高的可靠性（HA）和伸缩性，被应用于阿里巴巴各成员站点，同时在包括JD、当当在内的众多互联网项目中有着广泛应用。dubbo 通过高性能 RPC 实现服务的输出和输入功能，框架基于 Spring Framework 进行无缝集成，使用过程中基本看不到 Dubbo API的直接调用，Dubbo服务支持RMI、Hessian、Dubbo、WebService等众多通信协议，同时提供了对服务的监控和管理平台，属于一套完整的SOA解决方案。
详细介绍请参照官方地址：http://alibaba.github.io/dubbo-doc-static/Home-zh.htm，不再重复描述，本文主要记录了详细的开发整合步骤。引用一张官方提供的dubbo架构图：
Provider 暴露服务方称之为“服务提供者”。
Consumer 调用远程服务方称之为“服务消费者”。
Registry 服务注册与发现的中心目录服务称之为“服务注册中心”。
Monitor 统计服务的调用次调和调用时间的日志服务称之为“服务监控中心”。
- Container 服务运行“容器”。
二、源码构建
1、dubbo基于maven构建，需要先配置maven环境，当然如果你不想构建源码，也可以直接下载对应版本的发行包。
2、dubbo构建需要依赖opensesame组件，先通过 git 获取并安装opensesame，源码地址：
https://github.com/alibaba/opensesame
执行maven安装：mvn install
3、通过下面 git 地址获取对应版本的 dubbo 源码，官方推荐使用 dubbo 2.4.9，本文基于trunk版本构建。
https://github.com/alibaba/dubbo
maven构建：mvn clean install -Dmaven.test.skip，在漫长的等待后（过程需要通过网络下载依赖资源）会有如下提示，生成的 jar 包位于各自目录的target文件夹。
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] dubbo-parent ....................................... SUCCESS [ 1.272 s]
[INFO] dubbo-common ....................................... SUCCESS [ 4.572 s]
[INFO] dubbo-container .................................... SUCCESS [ 0.024 s]
[INFO] dubbo-container-api ................................ SUCCESS [ 1.148 s]
[INFO] dubbo-container-spring ............................. SUCCESS [ 0.524 s]
[INFO] dubbo-container-jetty .............................. SUCCESS [ 0.420 s]
[INFO] dubbo-container-log4j .............................. SUCCESS [ 0.448 s]
[INFO] dubbo-container-logback ............................ SUCCESS [ 0.468 s]
[INFO] dubbo-remoting ..................................... SUCCESS [ 0.016 s]
[INFO] dubbo-remoting-api ................................. SUCCESS [ 1.864 s]
[INFO] dubbo-remoting-netty ............................... SUCCESS [ 1.125 s]
[INFO] dubbo-remoting-mina ................................ SUCCESS [ 0.696 s]
[INFO] dubbo-remoting-grizzly ............................. SUCCESS [ 0.680 s]
[INFO] dubbo-remoting-p2p ................................. SUCCESS [ 1.048 s]
[INFO] dubbo-remoting-http ................................ SUCCESS [ 0.616 s]
[INFO] dubbo-remoting-zookeeper ........................... SUCCESS [ 0.716 s]
[INFO] dubbo-rpc .......................................... SUCCESS [ 0.016 s]
[INFO] dubbo-rpc-api ...................................... SUCCESS [ 1.608 s]
[INFO] dubbo-rpc-default .................................. SUCCESS [ 1.396 s]
[INFO] dubbo-rpc-injvm .................................... SUCCESS [ 0.760 s]
[INFO] dubbo-rpc-rmi ...................................... SUCCESS [ 0.416 s]
[INFO] dubbo-rpc-hessian .................................. SUCCESS [ 0.584 s]
[INFO] dubbo-rpc-http ..................................... SUCCESS [ 0.580 s]
[INFO] dubbo-rpc-webservice ............................... SUCCESS [ 0.536 s]
[INFO] dubbo-cluster ...................................... SUCCESS [ 2.208 s]
[INFO] dubbo-registry ..................................... SUCCESS [ 0.020 s]
[INFO] dubbo-registry-api ................................. SUCCESS [ 1.241 s]
[INFO] dubbo-monitor ...................................... SUCCESS [ 0.016 s]
[INFO] dubbo-monitor-api .................................. SUCCESS [ 0.464 s]
[INFO] dubbo-filter ....................................... SUCCESS [ 0.016 s]
[INFO] dubbo-filter-validation ............................ SUCCESS [ 0.608 s]
[INFO] dubbo-filter-cache ................................. SUCCESS [ 0.604 s]
[INFO] dubbo-registry-default ............................. SUCCESS [ 0.540 s]
[INFO] dubbo-monitor-default .............................. SUCCESS [ 0.588 s]
[INFO] dubbo-registry-multicast ........................... SUCCESS [ 0.632 s]
[INFO] dubbo-config ....................................... SUCCESS [ 0.016 s]
[INFO] dubbo-config-api ................................... SUCCESS [ 1.500 s]
[INFO] dubbo-config-spring ................................ SUCCESS [ 1.520 s]
[INFO] dubbo-rpc-thrift ................................... SUCCESS [ 1.032 s]
[INFO] dubbo-rpc-memcached ................................ SUCCESS [ 0.464 s]
[INFO] dubbo-rpc-redis .................................... SUCCESS [ 0.500 s]
[INFO] dubbo-registry-zookeeper ........................... SUCCESS [ 0.656 s]
[INFO] dubbo-registry-redis ............................... SUCCESS [ 0.640 s]
[INFO] dubbo .............................................. SUCCESS [ 1.009 s]
[INFO] dubbo-simple ....................................... SUCCESS [ 0.016 s]
[INFO] dubbo-registry-simple .............................. SUCCESS [01:43 min]
[INFO] dubbo-monitor-simple ............................... SUCCESS [ 10.379 s]
[INFO] dubbo-admin ........................................ SUCCESS [04:03 min]
[INFO] dubbo-demo ......................................... SUCCESS [ 0.016 s]
[INFO] dubbo-demo-api ..................................... SUCCESS [ 0.308 s]
[INFO] dubbo-demo-provider ................................ SUCCESS [ 2.700 s]
[INFO] dubbo-demo-consumer ................................ SUCCESS [ 2.745 s]
[INFO] dubbo-test ......................................... SUCCESS [ 0.012 s]
[INFO] dubbo-test-benchmark ............................... SUCCESS [01:01 min]
[INFO] dubbo-test-compatibility ........................... SUCCESS [ 0.188 s]
[INFO] dubbo-test-integration ............................. SUCCESS [ 0.052 s]
[INFO] dubbo-test-examples ................................ SUCCESS [ 1.640 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 07:42 min
[INFO] Finished at: 2015-01-20T14:36:43+08:00
[INFO] Final Memory: 282M/895M
[INFO] ------------------------------------------------------------------------
4、 构建过程中如果出现maven网络连接相关的异常信息，可以尝试将以下maven mirror 地址添加到 settings.xml 文件。
<mirror>
<id>CN</id>
<mirrorOf>central</mirrorOf>
<name>OSChina Central</name>
<url>http://maven.oschina.net/content/groups/public/</url>
</mirror> <mirror>
<id>kafeitu</id>
<mirrorOf>central</mirrorOf>
<name>Human Readable Name for this Mirror.</name>
<url>http://maven.kafeitu.me/nexus/content/repositories/public</url>
</mirror> <mirror>
<id>lvu.cn</id>
<name>lvu.cn</name>
<url>http://lvu.cn/nexus/content/groups/public</url>
<mirrorOf>*</mirrorOf>
</mirror>
三、Zookeeper部署（Registry 服务注册中心）
Dubbo 缺省配置通过 multicast 注册中心广播实现 Provider 和 Consumer 之间的简单远程过程调用（Simple RPC），不需要通过 Registry 注册中心进行注册调度，类似于spring rmi remoting调用，但由于不是Cluster部署，所以作为分布式RPC框架官方建议使用 Zookeeper 作为Registry注册中心服务器（同样支持Redis）实现服务的注册、发现、路由功能。Dubbo在Zookeeper服务器端只增加了dubbo数据节点（如下图），无需其他任何配置，所以只需安装或使用现有 Zookeeper 服务器即可，关于Zookeeper的安装部署可以参照之前的博文：http://www.cnblogs.com/lengfo/p/4146797.html，不再重复介绍。
Zookeeper同样支持集群部署，提供最终一致性数据服务，本文实验环境只使用了一台Linux服务器作为ZK Registry注册服务器，zoo.cfg配置文件如下。
# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/home/glf/zookeeperServer/data
dataLogDir=/home/glf/zookeeperServer/logs
# the port at which the clients will connect
clientPort=2181
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
# http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1
四、服务提供方开发（Provider）
1、创建Java测试项目 DubboDemo ，集成Spring Framework。由于dubbo基于Spring的Schema扩展进行加载，依赖于低版本spring，所以如果开发项目中使用高版本（spring 3.0及以上）会出现xml解析冲突，官方QA中也有相关提及：http://alibaba.github.io/dubbo-doc-static/FAQ-zh.htm，所以本文只集成了2.5.6版本spring，更多相关版本问题也有待进一步研究，Todo。
2、集成dubbo及相关依赖包，参照下图，如果使用dubbo其他特性可能需要依赖更多包，比如jedis。
3、创建测试服务接口（IGoodsManager）
package ibusiness;
public interface IGoodsManager {
public String LoadGoods();
}
4、创建测试服务实现类（GoodsManager）
package business; import com.alibaba.dubbo.rpc.RpcContext;
import ibusiness.IGoodsManager; public class GoodsManager implements IGoodsManager {
@Override
public String LoadGoods() {
return "可口可乐，雀巢咖啡 " + "/n response form provider: " + RpcContext.getContext().getLocalAddress();
}
}
5、通过spring 集成并配置dubbo测试服务，同时指定registry的zookeeper服务器地址。
<?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 服务提供者应用名称 -->
<dubbo:application name="demo-dubbo-provider-app" /> <!--dubbo 注册中心-->
<dubbo:registry address="zookeeper://10.129.221.64:2181" /> <!--服务提供者 端口-->
<dubbo:protocol name="dubbo" port="30001" /> <!--dubbo提供服务-->
<dubbo:service interface="ibusiness.IGoodsManager" ref="goodsService" /> <!--spring bean 对象-->
<bean id="goodsService" class="business.GoodsManager" />
</beans>
6、编写控制台程序启动spring容器，编译并打包Provider.jar
package dubboProvider; import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class DubboProvider {
public static void main(String[] args) {
try {
// 初始化Spring
ApplicationContext ctx = new ClassPathXmlApplicationContext("dubboProvider\\dubboProvider.xml"); System.out.println("dubbo provider is running...");
System.in.read();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
五、服务消费方开发（Consumer）
1、通过spring 配置指定registry的zookeeper地址，实现对dubbo远程服务的调用
<?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="demo-dubbo-consumer-app" /> <dubbo:registry address="zookeeper://10.129.221.64:2181" /> <!-- 和本地bean一样实现服务 -->
<dubbo:reference id="goodsService" interface="ibusiness.IGoodsManager" />
</beans>
2、编写调用测试客户端代码，从容器中获取远程bean并调用。
package dubboConsumer;
import ibusiness.IGoodsManager; import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class DubboConsumer { public static void main(String[] args) { // 初始化Spring
ApplicationContext ctx = new ClassPathXmlApplicationContext("dubboConsumer\\dubboConsumer.xml"); IGoodsManager goodsManager = (IGoodsManager) ctx.getBean("goodsService"); // 获取远程服务代理
String goodsStr = goodsManager.LoadGoods() ; // 执行远程方法
System.out.println(goodsStr); }
}
3、分别启动 provider、consumer 的测试程序发布和调用服务，即简单实现了基于 zookeeper registry 的 dubbo 远程过程调用。
六、More about dubbo
以上简单的展示dubbo的RPC服务能力，更多关于dubbo的集群管理、监控、负载均衡、高可用性、可扩展、伸缩性等相关内容请期待后续博文。