public void handleEvent(final ConnectedMessageChannel channel) {
      final Pooled<ByteBuffer> pooledReceiveBuffer = connection.allocate();
      try {
        final ByteBuffer receiveBuffer = pooledReceiveBuffer.getResource();
        int res = 0;
        try {
          res = channel.receive(receiveBuffer);
        } catch (IOException e) {
          connection.handleException(e);
          return;
        }
        if (res == -1) {
          connection.handleException(client.abruptClose(connection));
          return;
        }
        if (res == 0) {
          return;
        }
        receiveBuffer.flip();
        boolean starttls = false;
        final Set<String> saslMechs = new LinkedHashSet<String>();
        final byte msgType = receiveBuffer.get();
        switch (msgType) {
          case Protocol.CONNECTION_ALIVE:
            {
              client.trace("Client received connection alive");
              return;
            }
          case Protocol.CONNECTION_CLOSE:
            {
              client.trace("Client received connection close request");
              connection.handleIncomingCloseRequest();
              return;
            }
          case Protocol.CAPABILITIES:
            {
              client.trace("Client received capabilities response");
              while (receiveBuffer.hasRemaining()) {
                final byte type = receiveBuffer.get();
                final int len = receiveBuffer.get() & 0xff;
                final ByteBuffer data = Buffers.slice(receiveBuffer, len);
                switch (type) {
                  case Protocol.CAP_VERSION:
                    {
                      final byte version = data.get();
                      client.tracef(
                          "Client received capability: version %d",
                          Integer.valueOf(version & 0xff));
                      // We only support version zero, so knowing the other side's version is not
                      // useful presently
                      break;
                    }
                  case Protocol.CAP_SASL_MECH:
                    {
                      final String mechName = Buffers.getModifiedUtf8(data);
                      client.tracef("Client received capability: SASL mechanism %s", mechName);
                      if (!failedMechs.contains(mechName)
                          && !disallowedMechs.contains(mechName)
                          && (allowedMechs == null || allowedMechs.contains(mechName))) {
                        client.tracef("SASL mechanism %s added to allowed set", mechName);
                        saslMechs.add(mechName);
                      }
                      break;
                    }
                  case Protocol.CAP_STARTTLS:
                    {
                      client.trace("Client received capability: STARTTLS");
                      starttls = true;
                      break;
                    }
                  default:
                    {
                      client.tracef(
                          "Client received unknown capability %02x", Integer.valueOf(type & 0xff));
                      // unknown, skip it for forward compatibility.
                      break;
                    }
                }
              }
              if (starttls) {
                // only initiate starttls if not forbidden by config
                if (optionMap.get(Options.SSL_STARTTLS, true)) {
                  // Prepare the request message body
                  final Pooled<ByteBuffer> pooledSendBuffer = connection.allocate();
                  final ByteBuffer sendBuffer = pooledSendBuffer.getResource();
                  sendBuffer.put(Protocol.STARTTLS);
                  sendBuffer.flip();
                  connection.setReadListener(new StartTls(serverName));
                  connection.send(pooledSendBuffer);
                  // all set
                  return;
                }
              }

              if (saslMechs.isEmpty()) {
                connection.handleException(
                    new SaslException("No more authentication mechanisms to try"));
                return;
              }
              // OK now send our authentication request
              final OptionMap optionMap = connection.getOptionMap();
              final String userName = optionMap.get(RemotingOptions.AUTHORIZE_ID);
              final Map<String, ?> propertyMap =
                  SaslUtils.createPropertyMap(
                      optionMap, Channels.getOption(channel, Options.SECURE, false));
              final SaslClient saslClient;
              try {
                saslClient =
                    AccessController.doPrivileged(
                        new PrivilegedExceptionAction<SaslClient>() {
                          public SaslClient run() throws SaslException {
                            return Sasl.createSaslClient(
                                saslMechs.toArray(new String[saslMechs.size()]),
                                userName,
                                "remote",
                                serverName,
                                propertyMap,
                                callbackHandler);
                          }
                        },
                        accessControlContext);
              } catch (PrivilegedActionException e) {
                final SaslException se = (SaslException) e.getCause();
                connection.handleException(se);
                return;
              }
              final String mechanismName = saslClient.getMechanismName();
              client.tracef("Client initiating authentication using mechanism %s", mechanismName);
              // Prepare the request message body
              final Pooled<ByteBuffer> pooledSendBuffer = connection.allocate();
              final ByteBuffer sendBuffer = pooledSendBuffer.getResource();
              sendBuffer.put(Protocol.AUTH_REQUEST);
              Buffers.putModifiedUtf8(sendBuffer, mechanismName);
              sendBuffer.flip();
              connection.send(pooledSendBuffer);
              connection.setReadListener(new Authentication(saslClient, serverName));
              return;
            }
          default:
            {
              client.unknownProtocolId(msgType);
              connection.handleException(client.invalidMessage(connection));
              return;
            }
        }
      } catch (BufferUnderflowException e) {
        connection.handleException(client.invalidMessage(connection));
        return;
      } catch (BufferOverflowException e) {
        connection.handleException(client.invalidMessage(connection));
        return;
      } finally {
        pooledReceiveBuffer.free();
      }
    }