/*
 * 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.catalina;

import java.util.Set;

/**
 * Interface implemented by session managers that do not keep a complete copy of all sessions in memory but do know
 * where every session is. The BackupManager is an example of such a Manager as are implementations of the StoreManager
 * interface.
 * <p>
 * With the BackupManager, sessions can be primary (primary copy on this node), backup (backup copy on this node) or
 * proxy (only the session ID on this node). The identity of the primary and backup nodes are known for all sessions,
 * including proxy sessions.
 * <p>
 * With StoreManager implementations, sessions can be primary (session is in memory) or proxy (session is in the Store).
 */
public interface DistributedManager {

    /**
     * Returns the total session count for primary, backup and proxy.
     *
     * @return The total session count across the cluster.
     */
    int getActiveSessionsFull();

    /**
     * Returns the list of all sessions IDS (primary, backup and proxy).
     *
     * @return The complete set of sessions IDs across the cluster.
     */
    Set<String> getSessionIdsFull();
}