@see #createSubscriptionMessage(Agent, AID, DFAgentDescription, SearchConstraints)
@see #decodeNotification(String)
*/
public static ACLMessage createCancelMessage(Agent a, AID dfName, ACLMessage subscribe) {
ACLMessage cancel = new ACLMessage(ACLMessage.CANCEL);
cancel.addReceiver(dfName);
cancel.setLanguage(subscribe.getLanguage());
cancel.setOntology(subscribe.getOntology());
cancel.setProtocol(subscribe.getProtocol());
cancel.setConversationId(subscribe.getConversationId());
cancel.setContent(encodeCancel(dfName, subscribe));