public Document URLGetConstraintQuery(String url, String query, AlchemyAPI_ConstraintQueryParams params)
    throws IOException, XPathExpressionException,
           SAXException, ParserConfigurationException
	{
	    CheckURL(url);
	    if (null == query || query.length() < 2)
	        throw new IllegalArgumentException("Invalid constraint query specified");
	    
	    params.setUrl(url);
	    params.setCQuery(query);
	
	    return POST("URLGetConstraintQuery", "url", params);
	}