* Parses an InputSource into dom4j Document.
* Returns null in case of an exception.
*/
private static Document parse( Model model, InputSource is, ErrorReceiver receiver ) throws AbortException {
try {
ValidatorHandler validator = bindingFileSchema.newValidator();
// set up the pipe line as :
// /-> extensionChecker -> validator
// parser-> -<
// \-> DOM builder
SAXParserFactory pf = SAXParserFactory.newInstance();
pf.setNamespaceAware(true);
DOMBuilder builder = new DOMBuilder();
ErrorReceiverFilter controller = new ErrorReceiverFilter(receiver);
validator.setErrorHandler(controller);
XMLReader reader = pf.newSAXParser().getXMLReader();
reader.setErrorHandler(controller);
DTDExtensionBindingChecker checker = new DTDExtensionBindingChecker("", model.options, controller);
checker.setContentHandler(validator);