* </p>
 *
 * <p>
 * Example Usage:
 * </p>
 *
 * <pre>
 * XmlTransformer transformer = new XmlTransformer();
 * transformer.setNamespaceAware(true);
 * transformer.setCacheDuration(30);
 * transformer.addFieldRule("title", "/book/title/text()");
 * transformer.addFieldRule("author", "/book/author/name/text()");
 *