/// <summary>
/// Requests a download token for a given resource.
/// </summary>
/// <param name="virtualFilePath">Identifies the resource to be downloaded.</param>
/// <param name="includeFileHash">Whether a file hash for the
/// requested resource should be calculated and assigned to the
/// <see cref="DownloadToken.Md5FileHash"/> property of the returned
/// <see cref="DownloadToken"/>.</param>
/// <returns>A token that represents a granted resource download, optionally
/// limited to a given time frame (<see cref="TransferToken.ExpirationTime"/>).</returns>
/// <exception cref="VirtualResourceNotFoundException">If the submitted <paramref name="virtualFilePath"/>
/// does not match an existing resource.</exception>
/// <exception cref="ResourceAccessException">If the request was not authorized.</exception>
/// <exception cref="ResourceLockedException">If a lock to access the
/// resource was not granted.</exception>
public DownloadToken RequestDownloadToken(string virtualFilePath, bool includeFileHash)
{
return(SecureFunc(FileSystemTask.DownloadTokenRequest,
() => ReaderService.RequestDownloadToken(virtualFilePath, includeFileHash),
() => String.Format("Download token request for file [{0}] failed.", virtualFilePath)));
}