* start the background index merging thread
* @throws ConfigurationException
*/
public void init() throws ConfigurationException {
if(index == null) {
throw new ConfigurationException("No index target");
}
if(!index.isUpdatable()) {
throw new ConfigurationException("ResourceIndex is not updatable");
}
if(incoming == null) {
throw new ConfigurationException("No incoming");
}
if(runInterval > 0) {
thread = new UpdateThread(this,runInterval);
thread.start();
}