FailbackRegistry
ref = createProxy(map)
RegistryDirectory
DubboNamespaceHandler
registry.subscribe
ZookeeperRegistry
doSubscribe
创建protocol代理对象
refer
notify通知节点变化
消费者
subscribe
doRefer
RegistryProtocol
ReferenceConfig
init
registerBeanDefinitionParser(\"reference\
init方法解析xml中的标签
