Assumes that a given XML entity holds a valid URL and returns an
XMLEntityResolver.Parser for that URL.
LOGGER.entering(publicId, systemId);
Parser parser = null;
try {
// TODO: think about using alg from http://www.w3.org/International/O-URL-code.html
final URL systemUrl = new URL(PolicyUtils.Rfc2396.unquote(systemId));
final InputStream input = systemUrl.openStream();
final XMLStreamReader reader = new TidyXMLStreamReader(xmlInputFactory.createXMLStreamReader(systemId, input), input);
parser = new Parser(systemUrl, reader);
return parser;
} finally {
LOGGER.exiting(parser);
}