title: Change XML node attribute value via WCF servive
body: <pre><code>[ServiceContract]
  public interface IParametersXMLService
  {
      [OperationContract, XmlSerializerFormat]
      XmlNode GetCommonNode(string path);
  
      [OperationContract, XmlSerializerFormat]
      void SetCommonNode(string path, string value);
  }
  </code></pre>
  
  <p>Service implementation:</p>
  
  <pre><code>    public XmlNode GetCommonNode(string path)
      {
          XmlDocument xml = new XmlDocument();
          xml.Load(path);
          XmlNode node = (XmlNode)xml.DocumentElement;
          XmlNode commonNode = node.SelectSingleNode("/blabla/att);
          return commonNode;
      }
  
      public void SetCommonNode(string path, string value)
      {
          XmlDocument xml = new XmlDocument();
          xml.Load(path);
          XmlNode node = (XmlNode)xml.DocumentElement;
          XmlNode commonNode = node.SelectSingleNode("/blabla/att");
          commonNode.Attributes["List"].Value = value;
      }
  </code></pre>
  
  <p><code>GetCommonNode</code> works fine and returns my value.
  <code>SetCommonNode</code> does not change my value.
  Maybe I need to save this file after change?</p>