how to parse xml in web serivce

Please find the code


using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;
using System.IO;
using System.Data.SqlClient;
using System.Xml;
using System.Configuration;
namespace wsMyWebService
{
///

/// Summary description for Service1
///

[WebService(Namespace = "http://www.myurl.com/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ToolboxItem(false)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
// [System.Web.Script.Services.ScriptService]
public class xmlServices : System.Web.Services.WebService
{
static SqlConnection Globalconn;

public xmlServices () {

string connStr = ConfigurationManager.ConnectionStrings["wsMyWebService_DB"].ConnectionString;
Globalconn = new SqlConnection(connStr);
//Uncomment the following line if using designed components

//InitializeComponent();

}

[WebMethod]

public System.Xml.XmlDocument UDFxmlMethod(System.Xml.XmlDocument xmldoc)
{

if (xmldoc != null)
{

//Read nodes of xml for my query
System.Xml.XmlNode root = xmldoc.DocumentElement;

string strIdentifier = root.SelectSingleNode("/Data/Formula/Identifier").InnerText;
string strDataItem = root.SelectSingleNode("/Data/Formula/DataItem").InnerText;
string strTimePeriod = root.SelectSingleNode("/Data/Formula/TimePeriod").InnerText;
string strTimePeriodFlag = root.SelectSingleNode("/Data/Formula/TimePeriodFlag").InnerText; ;
string strDataPeriodType = root.SelectSingleNode("/Data/Formula/DataPeriodType").InnerText; ;
string strTimePeriodType = root.SelectSingleNode("/Data/Formula/TimePeriodType").InnerText; ;
string strCurType = root.SelectSingleNode("/Data/Formula/CurType").InnerText; ;


//Get Result from query and return as XmlDocument
string strResult;

strResult = this.getData(strIdentifier, strDataItem, strTimePeriod, strTimePeriodFlag, strDataPeriodType, strTimePeriodType,strCurType);



XElement returnXml = new XElement("Data",
new XElement("Formula",
new XElement("Identifier", strIdentifier),
new XElement("DataItem", strDataItem),
new XElement("TimePeriod", strTimePeriod),
new XElement("TimePeriodFlag", strTimePeriodFlag),
new XElement("DataPeriodType", strDataPeriodType),
new XElement("TimePeriodType", strTimePeriodType),
new XElement("Result", strResult)
)
);




XmlDocument returnXmlDoc = new XmlDocument();

returnXmlDoc.LoadXml(returnXml.ToString());

return returnXmlDoc;







}

else
{

System.Xml.XmlDocument emptyXml = new System.Xml.XmlDocument();

return emptyXml;

}

}

//----------------------------------------------------------

public string getData(string strIdentifier, string strDataItem, string strTimePeriod, string strTimePeriodFlag, string strDataPeriodType, string strTimePeriodType, string strCurType)
{

public string getData(string strIdentifier, string strDataItem, string strTimePeriod, string strTimePeriodFlag, string strDataPeriodType, string strTimePeriodType, string strCurType)
{



SqlCommand command;
SqlDataAdapter adapter;
DataSet ds;
DataTable dt = new DataTable();

//@strIdentifier varchar(50),
//@strDataItem varchar(50),
//@strTimePeriod varchar(50) = 'CURRENT',
//@strDataPeriodType varchar(50) = 'TFQ',
//@strTimePeriodType varchar(50)= 'Fiscal'

try
{
if (Globalconn.State == ConnectionState.Closed)
{
Globalconn.Open();
}
if (IsNumeric(strTimePeriodType) == true)
{
command = new SqlCommand("spMYSP", Globalconn);
strTimePeriodFlag = "R";
}
else
{
command = new SqlCommand("spMYSP_cur", Globalconn);
}
command.CommandTimeout = 100;
command.CommandType = CommandType.StoredProcedure;



command.Parameters.Add("@strIdentifier", SqlDbType.VarChar, 50).Value = strIdentifier;
command.Parameters.Add("@strDataItem", SqlDbType.VarChar, 50).Value = strDataItem;
command.Parameters.Add("@strTimePeriod", SqlDbType.VarChar, 50).Value = strTimePeriod;
command.Parameters.Add("@strTimePeriodFlag", SqlDbType.VarChar, 50).Value = strTimePeriodFlag;
command.Parameters.Add("@strDataPeriodType", SqlDbType.VarChar, 50).Value = strDataPeriodType;
command.Parameters.Add("@strTimePeriodType", SqlDbType.VarChar, 30).Value = strTimePeriodType;
command.Parameters.Add("@strCurType", SqlDbType.VarChar, 30).Value = strCurType;


adapter = new SqlDataAdapter(command);
ds = new DataSet();
adapter.Fill(ds, "MYDS");

dt = ds.Tables["MYDS"];


return dt.Rows[0][0].ToString();



}
catch (Exception ex)
{
// new ProcessLogger("Exception : " + ex.Message, "[Default].getData");
return "";
}

finally
{
Globalconn.Close();

}
}
//**********************************************************************************************//

public static Boolean IsNumeric(string stringToTest)
{
int result;
return int.TryParse(stringToTest, out result);
}

}
}