public PostedFile(FileDescription file, string fileName)
{
File = file;
RoomNames = new HashSet <string>();
ReadStream = new FileStream(fileName, FileMode.Open, FileAccess.Read);
}
public DownloadingFile(FileDescription file, string fullName)
{
File = file;
FullName = fullName;
WriteStream = new FileStream(fullName, FileMode.Create, FileAccess.Write);
}