Java学习笔记——dubbo服务之底层通讯协议Protocol

我们先来找到通讯协议的入口点吧。通过Protocol接口查找通讯协议入口点,我们根据接口的export方法搜索发现入口了,在ServiceConfig的doExportUrlsFor1Protocol方法,如下图:

 

然后我们进入 protocol.export(invoker)方法发现有很多实现类,根据spi(不懂的请看之前写的容器篇)查看配置文件能找到如下

 

registry=com.alibaba.dubbo.registry.integration.RegistryProtocol
dubbo=com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol   //这个是默认的,我们在Protocol接口上可以看到spi的注解
filter=com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper
listener=com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper
mock=com.alibaba.dubbo.rpc.support.MockProtocol
injvm=com.alibaba.dubbo.rpc.protocol.injvm.InjvmProtocol
rmi=com.alibaba.dubbo.rpc.protocol.rmi.RmiProtocol
hessian=com.alibaba.dubbo.rpc.protocol.hessian.HessianProtocol
com.alibaba.dubbo.rpc.protocol.http.HttpProtocol
com.alibaba.dubbo.rpc.protocol.webservice.WebServiceProtocol
thrift=com.alibaba.dubbo.rpc.protocol.thrift.ThriftProtocol
memcached=com.alibaba.dubbo.rpc.protocol.memcached.MemcachedProtocol
redis=com.alibaba.dubbo.rpc.protocol.redis.RedisProtocol
rest=com.alibaba.dubbo.rpc.protocol.rest.RestProtocol

 

 

 

进入DubboProtocol.export(Invoker<T> invoker)方法里面有个 openServer(url);

 

代码:

  private void openServer(URL url) {
        // find server.
        String key = url.getAddress();
        //client 也可以暴露一个只有server可以调用的服务。
        boolean isServer = url.getParameter(Constants.IS_SERVER_KEY,true);
        if (isServer) {
        ExchangeServer server = serverMap.get(key);
        if (server == null) {
        serverMap.put(key, createServer(url)); //createServer是创建服务
        } else {
        //server支持reset,配合override功能使用
        server.reset(url);
        }
        }
    }

    

继续进入createServer,上源码

 

    private ExchangeServer createServer(URL url) {
        //默认开启server关闭时发送readonly事件
        url = url.addParameterIfAbsent(Constants.CHANNEL_READONLYEVENT_SENT_KEY, Boolean.TRUE.toString());
        //默认开启heartbeat
        url = url.addParameterIfAbsent(Constants.HEARTBEAT_KEY, String.valueOf(Constants.DEFAULT_HEARTBEAT));
        String str = url.getParameter(Constants.SERVER_KEY, Constants.DEFAULT_REMOTING_SERVER);
        if (str != null && str.length() > 0 && ! ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str))
            throw new RpcException("Unsupported server type: " + str + ", url: " + url);
        url = url.addParameter(Constants.CODEC_KEY, Version.isCompatibleVersion() ? COMPATIBLE_CODEC_NAME : DubboCodec.NAME);
        ExchangeServer server;
        try {
            server = Exchangers.bind(url, requestHandler);
        } catch (RemotingException e) {
            throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
        }
        str = url.getParameter(Constants.CLIENT_KEY);
        if (str != null && str.length() > 0) {
            Set<String> supportedTypes = ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions();
            if (!supportedTypes.contains(str)) {
                throw new RpcException("Unsupported client type: " + str);
            }
        }
        return server;
    }

    

    dubbo从要暴漏的服务的URL中取得相关的配置(host,port等)进行服务端server的创建,同上面的server = Exchangers.bind(url, requestHandler) 正式创建服务。

    所以基本的创建步骤是

    export()  -->  openServer()  -->  createServer()  -->  server = Exchangers.bind(url, requestHandler);  

    

  

  我们进行来看 Exchangers.bind(url, requestHandler)

  

  源码:

public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
      if (url == null) {
          throw new IllegalArgumentException("url == null");
      }
      if (handler == null) {
          throw new IllegalArgumentException("handler == null");
      }
      url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
      return getExchanger(url).bind(url, handler);
  }

  

  然后通过getExchanger(url).bind(url, handler)的bing进入 HeaderExchanger类

  

  public ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
        return new HeaderExchangeServer(Transporters.bind(url, new DecodeHandler(new HeaderExchangeHandler(handler))));
    }

    

    在进入Transporters类的bing的

    

  public static Server bind(URL url, ChannelHandler... handlers) throws RemotingException {
         if (url == null) {
             throw new IllegalArgumentException("url == null");
         }
         if (handlers == null || handlers.length == 0) {
             throw new IllegalArgumentException("handlers == null");
         }
         ChannelHandler handler;
         if (handlers.length == 1) {
             handler = handlers[0];
         } else {
             handler = new ChannelHandlerDispatcher(handlers);
         }
         return getTransporter().bind(url, handler);
     }

     

     

     通过bing可以知道他讲调用:GrizzlyTransporter,MinaTransporter,NettyTransporter 通过spi默认是调用NettyTransporter

     到这里我们基本明白dubbo的通讯默认是交给了netty来处理,

     

     我们在看下doOPen方法

     

@Override
        protected void doOpen() throws Throwable {
            NettyHelper.setNettyLoggerFactory();
            ExecutorService boss = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerBoss", true));
            ExecutorService worker = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerWorker", true));
            ChannelFactory channelFactory = new NioServerSocketChannelFactory(boss, worker, getUrl().getPositiveParameter(Constants.IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS));
            bootstrap = new ServerBootstrap(channelFactory);
        
            final NettyHandler nettyHandler = new NettyHandler(getUrl(), this);
            channels = nettyHandler.getChannels();
            // https://issues.jboss.org/browse/NETTY-365
            // https://issues.jboss.org/browse/NETTY-379
            // final Timer timer = new HashedWheelTimer(new NamedThreadFactory("NettyIdleTimer", true));
            bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
                public ChannelPipeline getPipeline() {
                    NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec() ,getUrl(), NettyServer.this);
                    ChannelPipeline pipeline = Channels.pipeline();
                    /*int idleTimeout = getIdleTimeout();
                    if (idleTimeout > 10000) {
                        pipeline.addLast("timer", new IdleStateHandler(timer, idleTimeout / 1000, 0, 0));
                    }*/
                    pipeline.addLast("decoder", adapter.getDecoder());//解码
                    pipeline.addLast("encoder", adapter.getEncoder());//编码
                    pipeline.addLast("handler", nettyHandler);
                    return pipeline;
                }
            });
            // bind
            channel = bootstrap.bind(getBindAddress());
        }

  

 了解netty的同学,肯定早已习惯这个方法的写法,就是创建了netty的server嘛,到这里dubbo的服务创建完毕了,这个时候控制台见打印:

 [DUBBO] Start NettyServer bind /0.0.0.0:20880, export /192.168.4.241:20880, dubbo version: 2.8.4, current host: 127.0.0.1

猜你喜欢

转载自blog.csdn.net/SpringJavaMyBatis/article/details/87281108
0条评论
添加一条新回复
  
今日推荐