XML : Xercesc DOMDocument - Compare two XML documents

I am using xercesc (C++) library for processing XML documents with xercesc::XercesDOMParser class. What is the simplest way to compare two XML documents? Say, I use:

  XercesDOMParser parser1;  parser1.parse("1.xml");  DOMDocument* doc1 = parser1.getDocument();    XercesDOMParser parser2;  parser2.parse("2.xml");  DOMDocument* doc2 = parser2.getDocument();    

How can I know that doc1 and doc2 are identical from the xml point of view (i.e. they can have different spaces/end-of-lines/indentation, but represent same XML content)?