class LogBackup
{ 
    static void ArchiveToXML(LogStore logStore, string fileName) 
    {  
        LogArchiveSnapshot snapshot = logStore.CreateLogArchiveSnapshot();
        
        XmlTextWriter writer = new XmlTextWriter(fileName, Encoding.ASCII);
        
        writer.WriteStartElement("logArchive");
        foreach(FileRegion region in snapshot.ArchiveRegions) 
        {
            writer.WriteStartElement("fileRegion"); 
            writer.WriteElementString("path", region.Path); 
            writer.WriteElementString("length", region.FileLength.ToString()); 
            writer.WriteElementString("offset", region.Offset.ToString()); 
            using(Stream dataStream = region.GetStream()) 
            { 
                byte[] data = new byte[dataStream.Length]; 
                dataStream.Read(data, 0, data.Length); 
                writer.WriteElementString("data", Convert.ToBase64String(data)); 
            }
            writer.WriteEndElement();
        }
        writer.WriteEndElement(); 
        writer.Close(); 
        logStore.SetArchiveTail(snapshot.LastSequenceNumber); 
    }
    static void RestoreFromXML(string fileName) 
    { 
        using(XmlTextReader reader = new XmlTextReader(fileName)) 
        {
            reader.ReadStartElement("logArchive"); 
            while(reader.IsStartElement()) 
            { 
                string path = reader.ReadElementString("path"); 
                long length = Int64.Parse(reader.ReadElementString("length")); 
                long offset = Int64.Parse(reader.ReadElementString("offset")); 
                string dataString = reader.ReadElementString("data"); 
                byte[] data = Convert.FromBase64String(dataString); 
                FileStream fileStream;
                using(fileStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write)) 
                { 
                    fileStream.SetLength(length); 
                    fileStream.Position = offset; fileStream.Write(data, 0, data.Length); 
                }
            } 
        reader.ReadEndElement(); 
        } 
    } 
}