private void ackClientRequestForUpdatedFile() throws Exception{
        try {
            InputStream is = null;
            OutputStream os = null;
            ArrayList<String> updatedFileName = new ArrayList<String>();
            is = s.getInputStream();
            this.dataReader.setDataInputstream(is);
            DropboxFileTransferProtocolDeserializer deserializer = new DropboxFileTransferProtocolDeserializer(this.dataReader);
            boolean isHasNextFile = deserializer.getIsHasNextFile();
            while (isHasNextFile) {
                updatedFileName.add(deserializer.getFileName());
                isHasNextFile = deserializer.getIsHasNextFile();
            }
            
            byte[] clientSig = this.dataReader.readSignature();
            Signature mySig = this.dataReader.getSignature();
            if(!mySig.verify(clientSig)){
                System.out.println("Message not authentic and integral 1!");
            }

            os =s.getOutputStream();
            
            this.dataWriter.setDataOutputstream(os);
            //this.dataWriter.setDataOutputstream(os);
            
            DropboxFileTransferProtocolSerializer serializer = new DropboxFileTransferProtocolSerializer(this.dataWriter);
            for (int i = 0; i < updatedFileName.size(); i++) {
                String fullPath = DropboxConstants.DROPBOX_DIRECTORY + updatedFileName.get(i);
                File file = new File(fullPath);
                if (file.exists()) {
                    System.out.println("Will be sending file:" + updatedFileName.get(i));
                    serializer.syncSingleFile(updatedFileName.get(i), new FileOperation(DropboxConstants.ADD, file), new TextDecryptor(SynchronizationService.serversideFileCryptionKey));
                }
            }
            // end of the stream
            serializer.writeHasNextFileFlag(false);
        } catch (SignatureException ex) {
            Logger.getLogger(SynchronizationService.class.getName()).log(Level.SEVERE, null, ex);
        }
       }