I am new in qt. I am using QNetworkAccessManager's put method to upload a file to http server. I am able to send files of upto 600KB but bigger files fail to upload. Also i am not sure whether the code that i am using is optimized or not. This is what I am using.

@bool HTTPClient::sendFile(QString imagePath)
{
bool isSuccess = false;
initNetworkResponse();
QIODevice *file = new QFile(imagePath);
bool isOpened = file->open(QIODevice::ReadOnly);
QByteArray fileData;
fileData = file->readAll();

if(!isOpened)
{
    qDebug("file could not be opened!");
    return false;
}
else
{
    qDebug("file opened successfully!");
    qDebug("size: %d", fileData.size());

    if(fileData.size()>kMAX_UPLOAD_FILE_SIZE)
    {
    QMessageBox::information(NULL, "File transfer", "File is too big! Choose a file of size <15MB.");
    }
}

QUrl requestURI( cleanURL(QString(kROOTURL) + QString(kFILETRANSFER_URL)));
QNetworkRequest networkRequest = createRequestHeadder(requestURI);
networkRequest.setRawHeader(kCONTENT_NAME_KEY, kFILE_NAME);

QNetworkReply *response = NULL;
mNetworkManager = new NetworkAccessManager(this);

// Generate data
mNetworkManager->syncPut(networkRequest, fileData, response);

if(QNetworkReply::NoError == mNetworkError ||
   kNETWORK_REPLY_SUCCESS == mResponseCode)
{
    bool ok;
    QVariantMap result = Json::parse(mNetworkResponse, ok).toMap();

    if(ok)
    {
        isSuccess = true;
    }
}

file->close();
delete mNetworkManager;
mNetworkManager = NULL;
return isSuccess;
}@

Can some expert plz suggest a better way to upload and download bigger files in Qt?

Thanks
qt developer