[dubbo 源码之 ]1. 服务提供方如何发布服务 (3)

对于org.apache.dubbo.remoting.Transporter 的适配类选择有三种：MinaTransporter、 NettyTransporter、GrizzlyTransporter，关于JavaNIO：Apache Mina、JBoss Netty、Sun Grizzly 框架对比：传送门

NettyServer启动之后，回到org.apache.dubbo.registry.integration.RegistryProtocol#export方法，继续执行将服务注册到注册中心，我们以Zookeeper为例：

1.首先查找所有注册中心

final Registry registry = getRegistry(originInvoker); ... protected Registry getRegistry(final Invoker<?> originInvoker) { URL registryUrl = getRegistryUrl(originInvoker); return registryFactory.getRegistry(registryUrl); }

因为RegistryFactory是一个SPI扩展接口，代码中设置的为zookeeper，因此这里调用的是ZookeeperRegistryFactory，继承自：org.apache.dubbo.registry.support.AbstractRegistryFactory#getRegistry(org.apache.dubbo.common.URL),在此方法中调用了createRegistry，但是ZookeeperRegistryFactory重写了createRegistry,因此具体调用的是ZookeeperRegistryFactory#createRegistry，该方法返回了一个new ZookeeperRegistry(url, zookeeperTransporter)实例对象。

2.开始注册，RegistryProtocol#register方法执行注册动作，首先获取到我们在上一步找到的注册中心ZookeeperRegistry,ZookeeperRegistry 执行父类org.apache.dubbo.registry.support.FailbackRegistry#register，在该方法中会调用抽象方法：doRegister,ZookeeperRegistry 重写了改方法，则执行ZookeeperRegistry#doRegister ,如下：

@Override public void doRegister(URL url) { try { zkClient.create(toUrlPath(url), url.getParameter(DYNAMIC_KEY, true)); } catch (Throwable e) { throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e); } }

3.toUrlPath方法会把org.apache.dubbo.common.URL转换格式后存储到zookeeper,如下：

dubbo://172.16.44.21:20880/com.sxzhongf.deep.in.dubbo.api.service.IGreetingService?anyhost=true&application=deep-in-dubbo-first-provider&default=true&deprecated=false&dubbo=2.0.2&dynamic=true&generic=false&group=dubbo-sxzhongf-group&interface=com.sxzhongf.deep.in.dubbo.api.service.IGreetingService&methods=sayHello,testGeneric&pid=8480&release=2.7.5&revision=1.0.0&side=provider&timestamp=1582872610313&version=1.0.0 -----------------------转换------------------------ /dubbo/com.sxzhongf.deep.in.dubbo.api.service.IGreetingService/providers/dubbo%3A%2F%2F172.16.44.21%3A20880%2Fcom.sxzhongf.deep.in.dubbo.api.service.IGreetingService%3Fanyhost%3Dtrue%26application%3Ddeep-in-dubbo-first-provider%26default%3Dtrue%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26group%3Ddubbo-sxzhongf-group%26interface%3Dcom.sxzhongf.deep.in.dubbo.api.service.IGreetingService%26methods%3DsayHello%2CtestGeneric%26pid%3D8480%26release%3D2.7.5%26revision%3D1.0.0%26side%3Dprovider%26timestamp%3D1582872610313%26version%3D1.0.0

转换之后的格式其实就是我们在zookeeper中看到的一样了，不过有几个目录：

dubbo

com.sxzhongf.deep.in.dubbo.api.service.IGreetingService

providers

[zk: localhost:2181(CONNECTED) 2] ls /dubbo/com.sxzhongf.deep.in.dubbo.api.service.IGreetingService/providers [dubbo%3A%2F%2F172.16.44.21%3A20880%2Fcom.sxzhongf.deep.in.dubbo.api.service.IGreetingService%3Fanyhost%3Dtrue%26application%3Ddeep-in-dubbo-first-provider%26default%3Dtrue%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26group%3Ddubbo-sxzhongf-group%26interface%3Dcom.sxzhongf.deep.in.dubbo.api.service.IGreetingService%26methods%3DsayHello%2CtestGeneric%26pid%3D15716%26release%3D2.7.5%26revision%3D1.0.0%26side%3Dprovider%26timestamp%3D1582872850187%26version%3D1.0.0]

至此，服务消费端就可以从注册中心获取服务提供service进行调用了，下节我们继续来分析，消费端是如何从注册中心拉取service进行处理的。