What if you need to remove all the empty nodes in an XML document? It’ easy with this small subroutine. This might be useful to set fields to NULL when they have no value, especially when communicating between BizTalk and a WCF web service. You might often get serialization errors when, for example, a date/time field has an empty-string value. Better to pass no element to the web service (i.e. NULL) than a field with a bad value.

<pre>

        public static XmlDocument RemoveEmptyNodes(XmlDocument txd)
        {

           // make a clean copy so we don't accidentally destroy the byRef txd variable passed to us.
            XmlDocument xmldoc = new XmlDocument();
            xmldoc.LoadXml(txd.OuterXml);
            XmlNodeList emptyElements = xmldoc.SelectNodes(@"//*[not(node())]");
            for (int i = emptyElements.Count - 1; i >= 0; i--)
            {
               emptyElements[i].ParentNode.RemoveChild(emptyElements[i]);
            }
            xmldoc.InnerXml = xmldoc.InnerXml.Replace("", "");
            return xmldoc;
        }

</pre>

You can call the above code from a message assignment shape in an orchestration.
Just put the above code in a C# helper .DLL, make a reference to it from your orchestration, then you should be able to call it statically.