/*
   * Returns given node in XML document referred via an xpath expression using libxml2
   */
CHARSTRING fx__XML__GetElement(const CHARSTRING& p_XMLDoc,
				 const CHARSTRING& p_Xpath) {
    
    const char *v_XMLDoc = (const char *) static_cast<const unsigned  char*>(p_XMLDoc);
    xmlChar *xPath =  (xmlChar *) static_cast<const  char*>(p_Xpath);

  ....
      }

OCTETSRTING  v_XMLDOC_oct = unichar2oct(p_XMLDoc);
    const char *v_XMLDoc = (const char *) (const unsigned  char*)v_XMLDOC_oct;

   OCTETSRTING  v_XMLDOC_oct = unichar2oct(p_XMLDoc);
    size_t v_XMLDoc_len = v_XMLDOC_oct;.lengthof();
    char *v_XMLDoc;
   
   // Prepare v_XMLDoc
    v_XMLDoc = (char *) calloc( v_XMLDoc_len + 1, 1); // Allocate memory and init to 0
    memcpy((char *) v_XMLDoc,  (const char *) (const unsigned  char*) tmp_oct1,  v_XMLDoc_len);
   
   // Do the work

  // Don't forget
  free(v_XMLDoc);