package org.apache.helix.api.listeners;

/*
 * 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.
 */

import java.util.List;
import org.apache.helix.NotificationContext;
import org.apache.helix.model.CurrentState;

/**
 * Interface to implement to respond to changes in the current state
 */
public interface CurrentStateChangeListener {

  /**
   * Invoked when current state changes
   * @param instanceName name of the instance whose state changed
   * @param statesInfo a list of the current states
   * @param changeContext the change event and state
   */
  void onStateChange(String instanceName, List<CurrentState> statesInfo,
      NotificationContext changeContext);

}