Dubbo

精尽 Dubbo 源码分析 —— 调试环境搭建

本文基于 Dubbo 2.6.1 版本，望知悉。

1. 依赖工具

Maven
Git
JDK
IntelliJ IDEA

2. 源码拉取

从官方仓库 https://github.com/alibaba/dubbo Fork 出属于自己的仓库。为什么要 Fork ？既然开始阅读、调试源码，我们可能会写一些注释，有了自己的仓库，可以进行自由的提交。😈

使用 IntelliJ IDEA 从 Fork 出来的仓库拉取代码。拉取完成后，Maven 会下载依赖包，可能会花费一些时间，耐心等待下。

在等待的过程中，我们可以来看一张 Dubbo 的架构图

在图中，本文会涉及到的有三个角色：

Registry 注册中心，用于服务的注册与发现。
Provider 服务提供者，通过向 Registry 注册服务。
Consumer 服务消费者，通过从 Registry 发现服务。

另外，Consumer 对 Provider 的调用，直接发起，无需经过 Registry 。

Dubbo 提供了 dubbo-demo 项目，用于开发者快速入门。
本文也使用该项目，搭建调试环境。

3. Registry

Dubbo 提供了多种 Registry 的实现，参见《注册中心参考手册》。

在 dubbo-demo 项目中，使用 Multicast Registry 。
实际生产环境中，使用 Zookeeper Registry 。

友情提示：「3.1 Multicast Registry」和「3.2 Zookeeper Registry」二选一，建议先使用前者搭建调试环境，因为简单方便。

3.1 Multicast Registry

Multicast Registry 基于组播协议实现，详细参见文档《Multicast 注册中心》。

Multicast 注册中心不需要启动任何中心节点，只要广播地址一样，就可以互相发现。

注意，不需要启动！！！简单的说，本小节的内容可以直接跳过。

3.2 Zookeeper Registry

Zookeeper Registry 基于 Zookeeper 实现，详细参见文档《zookeeper 注册中心》。

搭建步骤如下：

1、启动 Zookeeper 服务。

$ pwd
/Users/yunai/百度云同步盘/Programs/Zookeeper/zookeeper-3.4.8

$ bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/yunai/百度云同步盘/Programs/Zookeeper/zookeeper-3.4.8/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

2、修改 dubbo-demo-provider.xml ，启动 Provider 。

<!--<dubbo:registry address="multicast://224.5.6.7:1234"/>-->
<dubbo:registry address="zookeeper://127.0.0.1:2181"/>

3、修改 dubbo-demo-consumer.xml ，启动 Consumer 。

<!--<dubbo:registry address="multicast://224.5.6.7:1234"/>-->
<dubbo:registry address="zookeeper://127.0.0.1:2181"/>

4. Provider

在 IDEA 中，右键 Debug 运行 com.alibaba.dubbo.demo.provider.Provider 。

当输出如下日志，表示成功：

[18/02/18 10:04:42:042 CST] main  INFO support.ClassPathXmlApplicationContext: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@cd2dae5: startup date [Sun Feb 18 10:04:42 CST 2018]; root of context hierarchy
[18/02/18 10:04:42:042 CST] main  INFO xml.XmlBeanDefinitionReader: Loading XML bean definitions from class path resource [META-INF/spring/dubbo-demo-provider.xml]
[18/02/18 10:04:42:042 CST] main  INFO logger.LoggerFactory: using logger: com.alibaba.dubbo.common.logger.log4j.Log4jLoggerAdapter
[18/02/18 10:04:53:053 CST] main  INFO config.AbstractConfig:  [DUBBO] The service ready on spring started. service: com.alibaba.dubbo.demo.DemoService, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:13:013 CST] main  INFO config.AbstractConfig:  [DUBBO] Export dubbo service com.alibaba.dubbo.demo.DemoService to local registry, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:13:013 CST] main  INFO config.AbstractConfig:  [DUBBO] Export dubbo service com.alibaba.dubbo.demo.DemoService to url dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&bind.ip=192.168.1.116&bind.port=20880&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&qos.port=22222&side=provider&timestamp=1518919503284, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:13:013 CST] main  INFO config.AbstractConfig:  [DUBBO] Register dubbo service com.alibaba.dubbo.demo.DemoService url dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&bind.ip=192.168.1.116&bind.port=20880&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&qos.port=22222&side=provider&timestamp=1518919503284 to registry registry://224.5.6.7:1234/com.alibaba.dubbo.registry.RegistryService?application=demo-provider&dubbo=2.0.0&pid=43392&qos.port=22222&registry=multicast&timestamp=1518919493265, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:13:013 CST] main  INFO transport.AbstractServer:  [DUBBO] Start NettyServer bind /0.0.0.0:20880, export /192.168.1.116:20880, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Register: dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Send broadcast message: register dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284 to /224.5.6.7:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Receive multicast message: register dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284 from /192.168.1.116:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Subscribe: provider://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&category=configurators&check=false&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Send broadcast message: subscribe provider://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&category=configurators&check=false&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284 to /224.5.6.7:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:20:020 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Receive multicast message: subscribe provider://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&category=configurators&check=false&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284 from /192.168.1.116:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 10:05:21:021 CST] main  WARN multicast.MulticastRegistry:  [DUBBO] Ignore empty notify urls for subscribe url provider://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&category=configurators&check=false&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43392&side=provider&timestamp=1518919503284, dubbo version: 2.0.0, current host: 192.168.1.116

注意，如果使用 Multicast Registry 作为注册中心，在 IDEA 中需要使用 Debug 模式运行，原因参见：dubbo-demo set “java.net.preferIPv4Stack” not work 。

5. Consumer

在 IDEA 中，右键 Debug 运行 com.alibaba.dubbo.demo.consumer.Consumer 。

当输出如下日志，表示成功：

[18/02/18 09:45:22:022 CST] main  INFO support.ClassPathXmlApplicationContext: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@cd2dae5: startup date [Sun Feb 18 09:45:22 CST 2018]; root of context hierarchy
[18/02/18 09:45:22:022 CST] main  INFO xml.XmlBeanDefinitionReader: Loading XML bean definitions from class path resource [META-INF/spring/dubbo-demo-consumer.xml]
[18/02/18 09:45:22:022 CST] main  INFO logger.LoggerFactory: using logger: com.alibaba.dubbo.common.logger.log4j.Log4jLoggerAdapter
[18/02/18 09:45:45:045 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Register: consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=consumers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Send broadcast message: register consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=consumers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457 to /224.5.6.7:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Subscribe: consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=providers,configurators,routers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Receive multicast message: register consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=consumers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457 from /192.168.1.116:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Send broadcast message: subscribe consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=providers,configurators,routers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457 to /224.5.6.7:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Receive multicast message: subscribe consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=providers,configurators,routers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457 from /192.168.1.116:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Receive multicast message: register dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43355&side=provider&timestamp=1518918226970 from /192.168.1.116:1234, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO multicast.MulticastRegistry:  [DUBBO] Notify urls for subscribe url consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=providers,configurators,routers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457, urls: [dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43355&side=provider&timestamp=1518918226970], dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO transport.AbstractClient:  [DUBBO] Successed connect to server /192.168.1.116:20880 from NettyClient 192.168.1.116 using dubbo version 2.0.0, channel is NettyChannel [channel=[id: 0x1b7bac12, /192.168.1.116:63856 => /192.168.1.116:20880]], dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] DubboMulticastRegistryReceiver  INFO transport.AbstractClient:  [DUBBO] Start NettyClient 123312.local/192.168.1.116 connect to the server /192.168.1.116:20880, dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] main  INFO multicast.MulticastRegistry:  [DUBBO] Notify urls for subscribe url consumer://192.168.1.116/com.alibaba.dubbo.demo.DemoService?application=demo-consumer&category=providers,configurators,routers&check=false&dubbo=2.0.0&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&side=consumer&timestamp=1518918323457, urls: [dubbo://192.168.1.116:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=demo-provider&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43355&side=provider&timestamp=1518918226970], dubbo version: 2.0.0, current host: 192.168.1.116
[18/02/18 09:45:45:045 CST] main  INFO config.AbstractConfig:  [DUBBO] Refer dubbo service com.alibaba.dubbo.demo.DemoService from url multicast://224.5.6.7:1234/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=demo-consumer&check=false&dubbo=2.0.0&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=43363&qos.port=33333&register.ip=192.168.1.116&remote.timestamp=1518918226970&side=consumer&timestamp=1518918323457, dubbo version: 2.0.0, current host: 192.168.1.116
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880
Hello world, response form provider: 192.168.1.116:20880

666. 彩蛋

笔者开始更新 Dubbo 源码解析系列，让我们在 2018 一起精尽 Dubbo 。

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