/*
 * 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.brooklyn.core.entity.trait;

import org.apache.brooklyn.api.entity.Entity;
import org.apache.brooklyn.api.sensor.AttributeSensor;
import org.apache.brooklyn.core.sensor.BasicNotificationSensor;
import org.apache.brooklyn.core.sensor.Sensors;

/**
 * A collection of entities that can change.
 */
public interface Changeable {

    AttributeSensor<Integer> GROUP_SIZE = Sensors.newIntegerSensor("group.members.count", "Number of members");

    BasicNotificationSensor<Entity> MEMBER_ADDED = new BasicNotificationSensor<Entity>(Entity.class, "group.members.added", "Entity added to group members");
    BasicNotificationSensor<Entity> MEMBER_REMOVED = new BasicNotificationSensor<Entity>(Entity.class, "group.members.removed", "Entity removed from group members");
}
