public void addRuleInstances (String prefix, Digester digester)
{
digester.addObjectCreate(prefix, SpotSceneModel.class.getName());
// set up rules to parse and set our fields
digester.addRule(prefix, new SetPropertyFieldsRule());
// create EditablePortal instances when we see <portal>
digester.addRule(prefix + "/portal", new PortalCreateRule(this));
digester.addRule(prefix + "/portal", new PortalFieldsRule());
digester.addSetNext(prefix + "/portal", "addPortal", Portal.class.getName());