/*
 * 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
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 */
package org.apache.cassandra.gms;

import java.net.InetAddress;

This is called by an instance of the IEndpointStateChangePublisher to notify
interested parties about changes in the the state associated with any endpoint.
For instance if node A figures there is a changes in state for an endpoint B
it notifies all interested parties of this change. It is upto to the registered
instance to decide what he does with this change. Not all modules maybe interested
in all state changes.
/**
 * This is called by an instance of the IEndpointStateChangePublisher to notify
 * interested parties about changes in the the state associated with any endpoint.
 * For instance if node A figures there is a changes in state for an endpoint B
 * it notifies all interested parties of this change. It is upto to the registered
 * instance to decide what he does with this change. Not all modules maybe interested
 * in all state changes.
 */
public interface IEndpointStateChangeSubscriber
{
    
Use to inform interested parties about the change in the state
for specified endpoint
Params:
endpoint – endpoint for which the state change occurred.
epState –  state that actually changed for the above endpoint./**
     * Use to inform interested parties about the change in the state
     * for specified endpoint
     *
     * @param endpoint endpoint for which the state change occurred.
     * @param epState  state that actually changed for the above endpoint.
     */
    public void onJoin(InetAddress endpoint, EndpointState epState);
    
    public void beforeChange(InetAddress endpoint, EndpointState currentState, ApplicationState newStateKey, VersionedValue newValue);

    public void onChange(InetAddress endpoint, ApplicationState state, VersionedValue value);

    public void onAlive(InetAddress endpoint, EndpointState state);

    public void onDead(InetAddress endpoint, EndpointState state);

    public void onRemove(InetAddress endpoint);

    
Called whenever a node is restarted. Note that there is no guarantee when that happens that the node was previously marked down. It will have only if state.isAlive() == false as state is from before the restarted node is marked up. /**
     * Called whenever a node is restarted.
     * Note that there is no guarantee when that happens that the node was
     * previously marked down. It will have only if {@code state.isAlive() == false}
     * as {@code state} is from before the restarted node is marked up.
     */
    public void onRestart(InetAddress endpoint, EndpointState state);
}