NAV dotnet and XDocument.Descendants

Hi

does anyone have a solution for the XDocument.Decendants function in NAV ?

in C#

var identity = xmlDoc.Descendants(XName.Get("Identity", "http://schemas.xmlsoap.org/ws/2006/02/addressingidentity")).FirstOrDefault();

that will return identity as XElement

Don't know how to do the .FirstOrDefault

Here is the code I have tried

OBJECT Codeunit 50437 Certificate Management
{
  OBJECT-PROPERTIES
  {
    Date=11.07.13;
    Time=11:06:45;
    Modified=Yes;
    Version List=BL7.00;
  }
  PROPERTIES
  {
    OnRun=BEGIN
            MESSAGE(GetServerCertificateValue('https://ws.b2b.is/Statements/20130201/BillService.svc'));
          END;

  }
  CODE
  {

    LOCAL PROCEDURE GetWsdlContent@1000000007(wsdlUrl@1000000000 : Text) wsdlContent : Text;
    VAR
      WebClient@1000000001 : DotNet "'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Net.WebClient";
    BEGIN
      WebClient := WebClient.WebClient;
      wsdlContent := WebClient.DownloadString(wsdlUrl);
    END;

    LOCAL PROCEDURE GetServerCertificateValue@1000000021(ServiceUrl@1000000000 : Text) encodedValue : Text;
    VAR
      xmlDoc@1000000001 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XDocument";
      xName@1000000004 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XName";
      Enum@1000000010 : DotNet "'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Linq.Enumerable";
      Identities@1000000003 : DotNet "'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Collections.Generic.IEnumerable`1";
      Identity@1000000005 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XElement";
      keyInfo@1000000007 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XElement";
      x509Data@1000000008 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XElement";
      x509Certificate@1000000009 : DotNet "'System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.System.Xml.Linq.XElement";
      wsdlUrl@1000000006 : Text;
      wsdlContent@1000000002 : Text;
    BEGIN
      wsdlUrl := ServiceUrl + '?wsdl';
      wsdlContent := GetWsdlContent(wsdlUrl);
      xmlDoc := xmlDoc.Parse(wsdlContent);
      Identities := xmlDoc.Descendants(xName.Get('Identity','http://schemas.xmlsoap.org/ws/2006/02/addressingidentity'));
      Enum := Identities.GetEnumerator;
      //Identity := Enum.FirstOrDefault(Identities);
      IF ISNULL(Identity) THEN
        ERROR(STRSUBSTNO('Unable to Parse Identity from Wsdl Content, Url:{%1}',wsdlUrl));
      keyInfo := Identity.Element(xName.Get('KeyInfo', 'http://www.w3.org/2000/09/xmldsig#'));
      IF ISNULL(keyInfo) THEN
        ERROR(STRSUBSTNO('Unable to Parse keyInfo from Wsdl Content, Url:{%1}', wsdlUrl));
      x509Data := keyInfo.Element(xName.Get('X509Data', 'http://www.w3.org/2000/09/xmldsig#'));
      IF ISNULL(x509Data) THEN
        ERROR(STRSUBSTNO('Unable to Parse keyInfo/X509Data from Wsdl Content, Url:{%1}', wsdlUrl));
      x509Certificate := x509Data.Element(xName.Get('X509Certificate', 'http://www.w3.org/2000/09/xmldsig#'));
      IF ISNULL(x509Certificate) THEN
        ERROR(STRSUBSTNO('Unable to Parse keyInfo/X509Data/x509Certificate from Wsdl Content, Url:{%1}', wsdlUrl));
      encodedValue := x509Certificate.Value;
    END;

    BEGIN
    {
      using System;
      using System.Collections.Generic;
      using System.Linq;
      using System.Text;
      using System.ServiceModel;
      using System.Xml.Linq;
      using System.Security.Cryptography.X509Certificates;
      using System.Net;

      /// <summary>
              /// Gets the content of the WSDL as string.
              /// </summary>
              /// <param name="wsdlUrl">The WSDL URL.</param>
              /// <returns></returns>
              private static string GetWsdlContent(string wsdlUrl)
              {
                  try
                  {
                      using (WebClient client = new WebClient())
                      {
                          var wsdlContent = client.DownloadString(wsdlUrl);
                          return wsdlContent;
                      }
                  }
                  catch (Exception ex)
                  {
                      throw new Exception(string.Format("Unable to Download Wsdl, Url:{0}, {1}", wsdlUrl, ex.Message), ex);
                  }
              }


      public static string GetServerCertificate(string address)
              {
                  var wsdlUrl = string.Concat(address, "?wsdl");
                  var wsdlContent = GetWsdlContent(wsdlUrl);
                  try
                  {
                      var xmlDoc = XDocument.Parse(wsdlContent);
                      var identity = xmlDoc.Descendants(XName.Get("Identity", "http://schemas.xmlsoap.org/ws/2006/02/addressingidentity")).FirstOrDefault();
                      if (identity == null)
                      {
                          throw new Exception(string.Format("Unable to Parse Identity from Wsdl Content, Url:{0}", wsdlUrl));
                      }
                      var keyInfo = identity.Element(XName.Get("KeyInfo", "http://www.w3.org/2000/09/xmldsig#"));
                      if (keyInfo == null)
                      {
                          throw new Exception(string.Format("Unable to Parse keyInfo from Wsdl Content, Url:{0}", wsdlUrl));
                      }
                      var x509Data = keyInfo.Element(XName.Get("X509Data", "http://www.w3.org/2000/09/xmldsig#"));
                      if (x509Data == null)
                      {
                          throw new Exception(string.Format("Unable to Parse keyInfo/X509Data from Wsdl Content, Url:{0}", wsdlUrl));
                      }
                      var x509Certificate = x509Data.Element(XName.Get("X509Certificate", "http://www.w3.org/2000/09/xmldsig#"));
                      if (x509Certificate == null)
                      {
                          throw new Exception(string.Format("Unable to Parse keyInfo/X509Data/x509Certificate from Wsdl Content, Url:{0}", wsdlUrl));
                      }
                      var encodedValue = x509Certificate.Value;
                  }
                  catch (Exception ex)
                  {
                      throw new Exception(string.Format("Unable to Parse Wsdl Content, Url:{0}, {1}", wsdlUrl, ex.Message), ex);
                  }
                  return encodedValue;
              }
    }
    END.
  }
}