版本声明

1. com.rabbitmq:amqp-client:4.3.0
2. RabbitMQ版本声明: 3.6.15

Connection

1. 这里的连接其实就表示的是TCP/IP socket连接，一个Connection有多个Channel,意味Connection会被设计为长连接，并且每个Channel一定有一个唯一标识，客户端请求和服务端响应都会携带这个标识，以区分是哪个通道。

连接过程分析

1. client打开与服务器的TCP/IP连接并发送一个协议头(protocol header).这只是client发送的数据，而不是作为方法格式的数据.
2. server使用其协议版本和其它属性，包括它支持安全机制列表(Start方法)进行响应.
3. client选择一种安全机制(Start-Ok).
4. server开始认证过程, 它使用SASL的质询-响应模型(challenge-response model). 它向客户端发送一个质询(Secure).
5. client向server发送一个认证响应(Secure-Ok). 例如，对于使用"plain"机制,响应会包含登录用户名和密码.
   server 重复质询(Secure) 或转到协商,发送一系列参数，如最大帧大小(Tune).
6. client接受或降低这些参数(Tune-Ok).
7. client 正式打开连接并选择一个虚拟主机(Open).
8. 服务器确认虚拟主机是一个有效的选择 (Open-Ok).
9. 客户端现在使用希望的连接.
10. 一个节点(client 或 server) 结束连接(Close).
11. 另一个节点对连接结束握手(Close-Ok).
12. server 和 client关闭它们的套接字连接.
13. 连接流转图
    

连接过程抓包分析

1. 整个连接过程,我们从抓包结果来分析，只关注AMQP协议即可
   

2. 第一步客户端发送Protocol-Hearder
   

3. 服务端响应Connection.start
   

4. 客户端发送Connection.Start-Ok
   

5. 服务端发送Connection.Tune
   

6. 客户端发送Connection.Tune-Ok
   

7. 客户端发送Connection.Open
   

8. 服务端发送Connection.Open-Ok
   

源码分析

1. uml图
   
2. 创建连接时序图
   

ConnectionFactory

1. 创建连接的工厂ConnectionFactory,包含创建连接的一些必备参数。

2. 核心方法newConnection()

   public Connection newConnection(ExecutorService executor, AddressResolver addressResolver, String clientProvidedName) throws IOException, TimeoutException { if(this.metricsCollector == null) { //这是一个空的收集，没有任何操作 this.metricsCollector = new NoOpMetricsCollector(); } // make sure we respect the provided thread factory //根据参数创建FrameHandlerFactory，BIO和NIO FrameHandlerFactory fhFactory = createFrameHandlerFactory(); //此executor是用于消费者消费使用的(consumerWorkServiceExecutor) ConnectionParams params = params(executor); // set client-provided via a client property if (clientProvidedName != null) { Map<String, Object> properties = new HashMap<String, Object>(params.getClientProperties()); properties.put("connection_name", clientProvidedName); params.setClientProperties(properties); } //默认自动恢复连接 if (isAutomaticRecoveryEnabled()) { // see com.rabbitmq.client.impl.recovery.RecoveryAwareAMQConnectionFactory#newConnection AutorecoveringConnection conn = new AutorecoveringConnection(params, fhFactory, addressResolver, metricsCollector); conn.init(); return conn; } else { List<Address> addrs = addressResolver.getAddresses(); Exception lastException = null; for (Address addr : addrs) { try { FrameHandler handler = fhFactory.create(addr); AMQConnection conn = createConnection(params, handler, metricsCollector); conn.start(); this.metricsCollector.newConnection(conn); return conn; } catch (IOException e) { lastException = e; } catch (TimeoutException te) { lastException = te; } } if (lastException != null) { if (lastException instanceof IOException) { throw (IOException) lastException; } else if (lastException instanceof TimeoutException) { throw (TimeoutException) lastException; } } throw new IOException("failed to connect"); } } 

3. createFrameHandlerFactory,FrameHandlerFactory

   protected synchronized FrameHandlerFactory createFrameHandlerFactory() throws IOException { if(nio) { if(this.frameHandlerFactory == null) { if(this.nioParams.getNioExecutor() == null && this.nioParams.getThreadFactory() == null) { this.nioParams.setThreadFactory(getThreadFactory()); } this.frameHandlerFactory = new SocketChannelFrameHandlerFactory(connectionTimeout, nioParams, isSSL(), sslContext); } return this.frameHandlerFactory; } else { return new SocketFrameHandlerFactory(connectionTimeout, factory, socketConf, isSSL(), this.shutdownExecutor); } } 

AMQConnection分析

1. AMQConnection详细注释

2. 起来启动的核心代码

   /** * Start up the connection, including the MainLoop thread. * Sends the protocol * version negotiation header, and runs through * Connection.Start/.StartOk, Connection.Tune/.TuneOk, and then * calls Connection.Open and waits for the OpenOk. Sets heart-beat * and frame max values after tuning has taken place. * @throws IOException if an error is encountered * either before, or during, protocol negotiation; * sub-classes {@link ProtocolVersionMismatchException} and * {@link PossibleAuthenticationFailureException} will be thrown in the * corresponding circumstances. {@link AuthenticationFailureException} * will be thrown if the broker closes the connection with ACCESS_REFUSED. * If an exception is thrown, connection resources allocated can all be * garbage collected when the connection object is no longer referenced. * * * client收到Connection.Tune方法后，必须要开始发送心跳, * 并在收到Connection.Open后，必须要开始监控.server在收到Connection.Tune-Ok后， * 需要开始发送和监控心跳． */ public void start() throws IOException, TimeoutException { //创建Consumer服务 initializeConsumerWorkService(); //创建长连接心跳 initializeHeartbeatSender(); //判断主循环是否在运行中 this._running = true; // Make sure that the first thing we do is to send the header, // which should cause any socket errors to show up for us, rather // than risking them pop out in the MainLoop /** * 先发送header，确保socket是否会发生错误，比在MainLoop(主事件循环)去确保要好。 */ AMQChannel.SimpleBlockingRpcContinuation connStartBlocker = new AMQChannel.SimpleBlockingRpcContinuation(); // We enqueue an RPC continuation here without sending an RPC // request, since the protocol specifies that after sending // the version negotiation header, the client (connection // initiator) is to wait for a connection.start method to // arrive. _channel0.enqueueRpc(connStartBlocker); try { // The following two lines are akin to AMQChannel's // transmit() method for this pseudo-RPC. _frameHandler.setTimeout(handshakeTimeout); //发送一个协议头开始新的连接，格式为'AMQP0091' _frameHandler.sendHeader(); } catch (IOException ioe) { _frameHandler.close(); throw ioe; } /** * 此处就是启动MainLoop(源码是 connection.startMainLoop()) * 把连接启动放入到framehandler的 initialize()方法中，这样的设计是否合理?? */ this._frameHandler.initialize(this); AMQP.Connection.Start connStart; AMQP.Connection.Tune connTune = null; try { connStart = (AMQP.Connection.Start) connStartBlocker.getReply(handshakeTimeout/2).getMethod(); _serverProperties = Collections.unmodifiableMap(connStart.getServerProperties()); Version serverVersion = new Version(connStart.getVersionMajor(), connStart.getVersionMinor()); if (!Version.checkVersion(clientVersion, serverVersion)) { throw new ProtocolVersionMismatchException(clientVersion, serverVersion); } //mechanisms(机制),返回的数据形如:AMQPLAIN PLAIN String[] mechanisms = connStart.getMechanisms().toString().split(" "); SaslMechanism sm = this.saslConfig.getSaslMechanism(mechanisms); if (sm == null) { throw new IOException("No compatible authentication mechanism found - " + "server offered [" + connStart.getMechanisms() + "]"); } LongString challenge = null; LongString response = sm.handleChallenge(null, this.username, this.password); do { //构建Start-OK(认证机制) Method method = (challenge == null) ? new AMQP.Connection.StartOk.Builder() .clientProperties(_clientProperties) .mechanism(sm.getName()) .response(response) .build() : new AMQP.Connection.SecureOk.Builder().response(response).build(); try { Method serverResponse = _channel0.rpc(method, handshakeTimeout/2).getMethod(); if (serverResponse instanceof AMQP.Connection.Tune) { connTune = (AMQP.Connection.Tune) serverResponse; } else { challenge = ((AMQP.Connection.Secure) serverResponse).getChallenge(); response = sm.handleChallenge(challenge, this.username, this.password); } } catch (ShutdownSignalException e) { Method shutdownMethod = e.getReason(); if (shutdownMethod instanceof AMQP.Connection.Close) { AMQP.Connection.Close shutdownClose = (AMQP.Connection.Close) shutdownMethod; if (shutdownClose.getReplyCode() == AMQP.ACCESS_REFUSED) { throw new AuthenticationFailureException(shutdownClose.getReplyText()); } } throw new PossibleAuthenticationFailureException(e); } } while (connTune == null); } catch (TimeoutException te) { _frameHandler.close(); throw te; } catch (ShutdownSignalException sse) { _frameHandler.close(); throw AMQChannel.wrap(sse); } catch(IOException ioe) { _frameHandler.close(); throw ioe; } try { //协商通道最大编号,协商规则如下 // (clientValue == 0 || serverValue == 0) ?Math.max(clientValue, serverValue) :Math.min(clientValue, serverValue); int channelMax = negotiateChannelMax(this.requestedChannelMax, connTune.getChannelMax()); //创建通道管理器 _channelManager = instantiateChannelManager(channelMax, threadFactory); //协商Frame的最大长度 int frameMax = negotiatedMaxValue(this.requestedFrameMax, connTune.getFrameMax()); this._frameMax = frameMax; //协商出心跳时间 int heartbeat = negotiatedMaxValue(this.requestedHeartbeat, connTune.getHeartbeat()); //发送心跳 setHeartbeat(heartbeat); //发送TuneOk _channel0.transmit(new AMQP.Connection.TuneOk.Builder() .channelMax(channelMax) .frameMax(frameMax) .heartbeat(heartbeat) .build()); //发送Open打开连接 _channel0.exnWrappingRpc(new AMQP.Connection.Open.Builder() .virtualHost(_virtualHost) .build()); } catch (IOException ioe) { _heartbeatSender.shutdown(); _frameHandler.close(); throw ioe; } catch (ShutdownSignalException sse) { _heartbeatSender.shutdown(); _frameHandler.close(); throw AMQChannel.wrap(sse); } // We can now respond to errors having finished tailoring the connection this._inConnectionNegotiation = false; }