public AMQConnection(ConnectionParams params, FrameHandler frameHandler)
    {
        checkPreconditions();
        this.username = params.getUsername();
        this.password = params.getPassword();
        this._frameHandler = frameHandler;
        this._virtualHost = params.getVirtualHost();
        this._exceptionHandler = params.getExceptionHandler();

        this._clientProperties = new HashMap<String, Object>(params.getClientProperties());
        this.requestedFrameMax = params.getRequestedFrameMax();
        this.requestedChannelMax = params.getRequestedChannelMax();
        this.requestedHeartbeat = params.getRequestedHeartbeat();
        this.shutdownTimeout = params.getShutdownTimeout();
        this.saslConfig = params.getSaslConfig();
        this.executor = params.getExecutor();
        this.threadFactory = params.getThreadFactory();

        this._channelManager = null;

        this._brokerInitiatedShutdown = false;

        this._inConnectionNegotiation = true; // we start out waiting for the first protocol response
    }