package org.apache.helix.metaclient.api;

/*
 * 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.
 */

/**
 * Listener interface for events on a particular key, including entry creating, deleting and value change.
 */
public interface DataChangeListener {
  enum ChangeType {
    ENTRY_CREATED,     // Entry created of the specific path that the listener register to
    ENTRY_DELETED,     // Entry deleted of the specific path that the listener register to
    ENTRY_UPDATE      // Entry value updated
  }

  void handleDataChange(String key, Object data, ChangeType changeType) throws Exception;
}
