src/main/java/org/fcrepo/mint/HttpPidMinter.java
private static String xpath( final String xml, final XPathExpression xpath )
            throws ParserConfigurationException, SAXException, IOException, XPathExpressionException {
        final DocumentBuilder builder = DOCUMENT_BUILDER_FACTORY.newDocumentBuilder();
        final Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes()));
        return xpath.evaluate(doc);
    }
private static String xpath( final String xml, final XPathExpression xpath )
            throws ParserConfigurationException, SAXException, IOException, XPathExpressionException {
        final DocumentBuilder builder = DOCUMENT_BUILDER_FACTORY.newDocumentBuilder();
        final Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes()));
        return xpath.evaluate(doc);
    }
Extract the desired identifier value from an XML response using XPath