/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License. You may obtain a
 * copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package org.apache.geode.management.membership;

/**
 * A listener whose callback methods are invoked when members join or leave the GemFire distributed
 * system.
 *
 * @see org.apache.geode.management.ManagementService#addMembershipListener
 *
 * @since GemFire 8.0
 */
public interface MembershipListener {

  /**
   * Invoked when a member has joined the distributed system
   *
   * @param event the triggering event
   */
  void memberJoined(MembershipEvent event);

  /**
   * Invoked when a member has gracefully left the distributed system. This occurs when the member
   * took action to remove itself from the distributed system.
   *
   * @param event the triggering event
   */
  void memberLeft(MembershipEvent event);

  /**
   * Invoked when a member has unexpectedly left the distributed system. This occurs when a member
   * process terminates abnormally or is forcibly removed from the distributed system by another
   * process, such as from
   * <a href=../distributed/DistributedSystem.html#member-timeout> failure detection</a>,
   * or <a href=../distributed/DistributedSystem.html#enable-network-partition-detection>
   * network partition detection</a> processing.
   *
   * @param event the triggering event
   */
  void memberCrashed(MembershipEvent event);

}
