public void invoke(final String source, final Map params)
throws InvokerException {
SCXML scxml = null;
try {
scxml = SCXMLDigester.digest(source,
new SimpleErrorHandler(), null);
} catch (ModelException me) {
throw new InvokerException(me.getMessage(), me.getCause());
} catch (IOException ioe) {
throw new InvokerException(ioe.getMessage(), ioe.getCause());
} catch (SAXException se) {