Convert ADO Stream and Recordset to XML

When working with older applications, i.e. pre-.NET, its helpful with functions that converts ADO Streams and Recordset to XML and vice versa. Especially when older applications should be migrated or communicate with .NET applications and its prefered to rewrite as little as possible. Another approach would be to use JSON.

Anyway, here are a couple of converting functions that are useful.

Recordset <-> XML

/// <summary>
/// Convert XML to recordset
/// </summary>
/// <param name="sXML"></param>
/// <returns>Recordset</returns>
public static Recordset recordsetFromXML(string sXML)
{
    if (string.IsNullOrEmpty(sXML))
    {
        // Nothing to convert
        return null;
    }

    // Open an ADO Stream
    var oStream = new Stream();
    oStream.Open(Missing.Value, ConnectModeEnum.adModeUnknown,
                 StreamOpenOptionsEnum.adOpenStreamUnspecified,
                 "", "");

    // Load the XML string into stream
    oStream.WriteText(sXML, StreamWriteEnum.adWriteChar);
    oStream.Position = 0;

    // Create empty recordset
    var oRecordset = new Recordset();

    // Read the XML stream
    oRecordset.Open(oStream, Missing.Value,
                    CursorTypeEnum.adOpenUnspecified,
                    LockTypeEnum.adLockUnspecified, 0);
    oStream.Close();

    //Return the recordset
    return oRecordset;
}

/// <summary>
/// Convert recordset to XML
/// </summary>
/// <param name="oRecordset"></param>
/// <returns>String</returns>
public static string recordsetToXML(Recordset oRecordset)
{
    string xmlString = "";

    if (oRecordset != null)
    {
        // Load recordset into stream
        var oStream = new Stream();
        oRecordset.Save(oStream, PersistFormatEnum.adPersistXML);

        // Get the XML
        xmlString = oStream.ReadText(oStream.Size);
    }

    return xmlString;
}

Stream <-> XML

/// <summary>
/// Convert XML to stream
/// </summary>
/// <param name="sXML"></param>
/// <returns>Stream</returns>
public static Stream streamFromXML(string sXML)
{
    // Load XML into XmlDocument
    var oXML = new XmlDocument();
    oXML.InnerXml = sXML;

    // Get the STREAM element
    var aNode = oXML.GetElementsByTagName("STREAM")[0];

    // Create a binary stream
    var oStream = new Stream();
    oStream.Type = StreamTypeEnum.adTypeBinary;
    oStream.Open(Missing.Value, ConnectModeEnum.adModeUnknown,
                 StreamOpenOptionsEnum.adOpenStreamUnspecified,
                 "", "");

    // Load XML
    oStream.Write(Convert.FromBase64String(aNode.InnerXml));
    oStream.Position = 0;

    return oStream;
}

/// <summary>
/// Convert stream to XML
/// </summary>
/// <param name="oStream"></param>
/// <returns>String</returns>
public static string streamToXML(Stream oStream)
{
    // Create XmlDocument
    var oXML = new XmlDocument();
    oXML.AppendChild(oXML.CreateProcessingInstruction("xml", "version='1.0'"));

    // Add STREAM element to hold the binary data
    XmlElement oElem = oXML.CreateElement("STREAM");

    // Define type of value
    XmlAttribute dt = oXML.CreateAttribute("dt", "dt", "urn:schemas-microsoft-com:datatypes");
    dt.Value = "bin.base64";
    oElem.SetAttributeNode(dt);

    // Convert stream data to string
    oElem.InnerXml = Convert.ToBase64String((byte[])oStream.Read(-1));
    oXML.AppendChild(oElem);

    // Return Xml
    return oXML.InnerXml;
}