* is possible to change the external variable configuration at runtime.
*
*/
void initExternalVariables() {
List<Element> conf = _pconf.getExtensionElement(ExternalVariableConf.EXTVARCONF_ELEMENT);
_extVarConf = new ExternalVariableConf(conf);
_evm = new ExternalVariableManager(_pid, _extVarConf, _engine._contexts.externalVariableEngines, _oprocess);
}