DefaultTreeModel model = (DefaultTreeModel) serviceExplorer.getModel();
if (messageBus instanceof ServerMessageBus) {
// this is the serverside bus.
ServerMessageBus smb = (ServerMessageBus) messageBus;
List<MessageCallback> receivers = smb.getReceivers(currentlySelectedService);
DefaultMutableTreeNode receiversNode
= new DefaultMutableTreeNode("Receivers (" + receivers.size() + ")", true);
for (MessageCallback mc : receivers) {