registry  注册中心  Multicast Zookeeper Redis Simple 等实现
cluster   集群模块
common    Util 类和通用模型
config    配置模块
rpc       远程调用模块
remoting  远程通信模块
container 容器模块
filter    过滤器 
monitor   监控模块
serialization  序列化模块
bootstrap
plugin    插件
demo      例子


cluster   集群模块

Merge the directory invokers to a virtual invoker.

将多个服务提供方伪装成一个提供方，实现 负载均衡, 容错，路由等功能
集群地址列表  静态配置 或 基于注册中心 

 
Invoker
cluster  
集群容错模式 
failover failfast failsafe failback forking

FailsafeClusterInvoker
失败安全，出现异常时，直接忽略，通常用于写入审计日志等操作

FailoverClusterInvoker
失败转移，当出现失败，重试其它服务器，通常用于读操作，但重试会带来更长延迟

int retryCount = getUrl().getMethodParameter(invocation.getMethodName(), Constants.RETRIES_KEY, Constants.DEFAULT_RETRIES) + 1;

FailbackClusterInvoker
失败自动恢复，后台记录失败请求，定时重发，通常用于消息通知操作

list      Directory    (static registry)
route     Router       (script condition)
select    LoadBalance  (Random RandomRobin LeastActive)
invoke    Invoker

com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker 


public Result invoke(final Invocation invocation) throws RpcException {
    checkWheatherDestoried();
    LoadBalance loadbalance;
    List<Invoker<T>> invokers = list(invocation);
    if (invokers != null && invokers.size() > 0) {
        loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
        .getMethodParameter(invocation.getMethodName(),Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
    } else {
        loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE);
    }
    RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
    return doInvoke(invocation, invokers, loadbalance);
}

protected  List<Invoker<T>> list(Invocation invocation) throws RpcException {
    List<Invoker<T>> invokers = directory.list(invocation);
    return invokers;
}


configurator   配置 采用URL作为配置信息的统一格式 




common    Util 类和通用模型

com.alibaba.dubbo.common.URL


rpc 远程调用模块
抽象各种协议，动态代理，只包含一对一的调用
com.alibaba.dubbo.rpc.protocol

DubboProtocol extends AbstractProtocol 
public abstract class AbstractProtocol implements Protocol


HttpProtocol
HessianProtocol
HttpProtocol
InjvmProtocol
MemcachedProtocol
RedisProtocol
RmiProtocol



remoting 远程通信模块
提供多种客户端和服务端通信功能
支持 Netty Mina Grizzly 等 NIO 框架

Exchange Transport

exchange 
抽象了 Request 和 Response，并为其添加很多特性 

transport 
抽象网络传输层，只负责抽象单向消息传输
请求消息由 Client 端发出，Server 端接收
响应消息由 Server 端发出，Client端接收
transport 是在网络库上层的一层抽象

com.alibaba.dubbo.remoting.transport.netty.NettyServer
com.alibaba.dubbo.remoting.transport.netty.NettyClient

com.alibaba.dubbo.remoting.transport.AbstractEndpoint

com.alibaba.dubbo.remoting.Endpoint
void send(Object message) throws RemotingException;
//  sent 是否已发送完成
void send(Object message, boolean sent) throws RemotingException;
URL getUrl();
ChannelHandler getChannelHandler();
InetSocketAddress getLocalAddress();
void close();
void close(int timeout);




container 容器模块

Container接口  main方法加载
com.alibaba.dubbo.container.Container

@SPI("spring")
public interface Container 

com.alibaba.dubbo.container.spring.SpringContainer

/META-INF/dubbo/internal/com.alibaba.dubbo.container.Container

spring=com.alibaba.dubbo.container.spring.SpringContainer
javaconfig=com.alibaba.dubbo.container.javaconfig.JavaConfigContainer
jetty=com.alibaba.dubbo.container.jetty.JettyContainer
log4j=com.alibaba.dubbo.container.log4j.Log4jContainer
logback=com.alibaba.dubbo.container.logback.LogbackContainer




filter

com.alibaba.dubbo.rpc.Filter

com.alibaba.dubbo.rpc.filter.TimeoutFilter

执行timeout，log记录  ,类似慢查询日志



@Activate(group = Constants.PROVIDER)
public class TimeoutFilter implements Filter {
    private static final Logger logger = LoggerFactory.getLogger(TimeoutFilter.class);
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        long start = System.currentTimeMillis();
        Result result = invoker.invoke(invocation);
        long elapsed = System.currentTimeMillis() - start;
        if (invoker.getUrl() != null && elapsed > invoker.getUrl().getMethodParameter(invocation.getMethodName(),"timeout", Integer.MAX_VALUE)) {
            if (logger.isWarnEnabled()) {
                logger.warn("invoke time out. method: " + invocation.getMethodName()
                    + "arguments: " + Arrays.toString(invocation.getArguments()) + " , url is "
                    + invoker.getUrl() + ", invoke elapsed " + elapsed + " ms.");
             }
        }
        return result;
    }    
}





serialization 序列化模块

@SPI("hessian2")
public interface Serialization

com.alibaba.dubbo.common.serialize.support.hessian.Hessian2Serialization
com.alibaba.dubbo.common.serialize.support.json.FastJsonSerialization