本文解决的问题是：本Peer节点如何接收其他节点的数据，接到数据如何处理？

之前两节的分析是命令来源是CLI client，如何连接到Devops服务器、如何发送给Consensus模块、如何发送给ChainCodeSupportClient等。

接下来分析本文要讨论的问题

1）在进行网络初始化的过程中执行以下内容，在创建节点Engine过程中该节点作为客户端的身份连接到其他Peer

peerServer, err = peer.NewPeerWithEngine(secHelperFunc, helper.GetEngine)

</pre><pre name="code" class="cpp" style="font-size: 15px;">func (p *Impl) chatWithPeer(address string) error {
	peerLogger.Debugf("Initiating Chat with peer address: %s", address)
	conn, err := NewPeerClientConnectionWithAddress(address)
	if err != nil {
		peerLogger.Errorf("Error creating connection to peer address %s: %s", address, err)
		return err
	}
	serverClient := pb.NewPeerClient(conn)
	ctx := context.Background()
	stream, err := serverClient.Chat(ctx)
	if err != nil {
		peerLogger.Errorf("Error establishing chat with peer address %s: %s", address, err)
		return err
	}
	peerLogger.Debugf("Established Chat with peer address: %s", address)
	err = p.handleChat(ctx, stream, true)
	stream.CloseSend()
	if err != nil {
		peerLogger.Errorf("Ending Chat with peer address %s due to error: %s", address, err)
		return err
	}
	return nil
}

2.在handleChat执行过程中，建立消息循环，而这里的handler.HandleMessage。这个handler之前介绍过，是Engine的消息响应句柄，该消息响应处理来自于Consensus模块

func (p *Impl) handleChat(ctx context.Context, stream ChatStream, initiatedStream bool) error {
	deadline, ok := ctx.Deadline()
	peerLogger.Debugf("Current context deadline = %s, ok = %v", deadline, ok)
	handler, err := p.handlerFactory(p, stream, initiatedStream, nil)
	if err != nil {
		return fmt.Errorf("Error creating handler during handleChat initiation: %s", err)
	}
	defer handler.Stop()
	for {
		in, err := stream.Recv()
		if err == io.EOF {
			peerLogger.Debug("Received EOF, ending Chat")
			return nil
		}
		if err != nil {
			e := fmt.Errorf("Error during Chat, stopping handler: %s", err)
			peerLogger.Error(e.Error())
			return e
		}
		err = handler.HandleMessage(in)
		if err != nil {
			peerLogger.Errorf("Error handling message: %s", err)
			//return err
		}
	}
}

3.HandleMessage函数consenterChan 这个channel比较重要，该写入操作会触发engine.consensusFan的消息循环

func (handler *ConsensusHandler) HandleMessage(msg *pb.Message) error {
	if msg.Type == pb.Message_CONSENSUS {
		senderPE, _ := handler.To()
		select {
		case handler.consenterChan <- &util.Message{
			Msg:    msg,
			Sender: senderPE.ID,
		}:
			return nil
		default:
			err := fmt.Errorf("Message channel for %v full, rejecting", senderPE.ID)
			logger.Errorf("Failed to queue consensus message because: %v", err)
			return err
		}
	}

	if logger.IsEnabledFor(logging.DEBUG) {
		logger.Debugf("Did not handle message of type %s, passing on to next MessageHandler", msg.Type)
	}
	return handler.MessageHandler.HandleMessage(msg)
}
4.看到RecvMsg这个函数是不是有点眼熟，这个操作和  hyperledger fabric 结构分析 最后一个流程是一样的。

func GetEngine(coord peer.MessageHandlerCoordinator) (peer.Engine, error) {
	var err error
	engineOnce.Do(func() {
		engine = new(EngineImpl)
		engine.helper = NewHelper(coord)
		engine.consenter = controller.NewConsenter(engine.helper)
		engine.helper.setConsenter(engine.consenter)
		engine.peerEndpoint, err = coord.GetPeerEndpoint()
		engine.consensusFan = util.NewMessageFan()

		go func() {
			logger.Debug("Starting up message thread for consenter")

			// The channel never closes, so this should never break
			for msg := range engine.consensusFan.GetOutChannel() {
				engine.consenter.RecvMsg(msg.Msg, msg.Sender)
			}
		}()
	})
	return engine, err
}
5.再往下的流程与 hyperledger fabric 结构分析（三）中的一致。