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FileRegion Class

Represents a region of a file to be archived. This class cannot be inherited.

Namespace: System.IO.Log
Assembly: System.IO.Log (in system.io.log.dll)

'Declaration
Public NotInheritable Class FileRegion
'Usage
Dim instance As FileRegion

public final class FileRegion
public final class FileRegion
Not applicable.

A LogArchiveSnapshot object contains the information necessary to generate a consistent backup of the data in a LogStore. The actual data is contained in the enumerable collection of FileRegion objects returned by the ArchiveRegions property. Each FileRegion instance represents a sequence of bytes in a file that must be archived.

The following example demonstrates how to archive a log store to XML using the LogStore and FileRegion classes.

class LogBackup
{
    static void ArchiveToXML(LogStore logStore, string fileName)
    {
        

        LogArchiveSnapshot snapshot = logStore.CreateLogArchiveSnapshot();
        {
            XmlTextWriter writer = new XmlTextWriter(fileName, System.Text.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", System.Convert.ToBase64String(data));
                }

                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;
                long length;
                long offset;
                path = reader.ReadElementString("path");
                length = System.Int64.Parse(reader.ReadElementString("length"));
                offset = System.Int64.Parse(reader.ReadElementString("offset"));
                string dataString = reader.ReadElementString("data");
                byte[] data = System.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();
        }
    }
}

System.Object
  System.IO.Log.FileRegion

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0

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