private String NSIntroduceSendDownloadSession(boolean metFM) {
		if (metFM){
			if (previousSendReceive(MessageNames.EMPTY,MessageNames.BEGIN))
				return MessageNames.DONE;
		}
		else{
			if (previousSendReceive(MessageNames.EMPTY,MessageNames.BEGIN))
				return MessageNames.WELCOME;
			if ((_previousSendMessage.equals(MessageNames.WELCOME)) ||
					(_previousSendMessage.equals(MessageNames.DONE))){
				if ((_previousReceiveMessage.equals(MessageNames.CONTAINFILE)) ||
						(_previousReceiveMessage.equals(MessageNames.ENDLIST)) ||
						(_previousReceiveMessage.equals(MessageNames.CONTAINNAMESERVER)))
					return MessageNames.DONE;
			}
			if (previousSendReceive(MessageNames.DONE,
									MessageNames.ENDSESSION)){
					return MessageNames.DONE;
			}
		}
		return MessageNames.EMPTY;
	}