protocol层：远程调用层，负责通信
Javassist.getInvoker
RegistryProtocol
serialize层：远程调用
...
Protocol$Adaptive
RestProtocol
ServiceConfigexport()
proxy
invokerMockClusterWrapper(FailoverCluster(directory))
服务注册与发布
notify
ZookeeperRegistry
注解配置文件
RegistryFactory->ZookeeperRegistryFactory->CuratorTransporter
启动netty
DubboRegistry
monitor层：监控层
Invoker
DubboNamespaceHandler
client
@ReferenceISayHelloService service
zk
ServiceConfigServiceBean
RegistryProtocoldoRefer
config层：提供配置信息
notify()
connectrequest
invoker
1.第一次启动初始化2.服务地址变化
register层：服务注册层，prover->register
cluster层：provider部署在多台机器上，多个provider组成
wrapper
ReferenceConfig.get()
service层：provider和consumer
代理
DubboProtocol
proxy层：代理层，通过代理通信
exchange层：信息交换
exportmap
