001    /**
002     *
003     *  Licensed to the Apache Software Foundation (ASF) under one or more
004     *  contributor license agreements.  See the NOTICE file distributed with
005     *  this work for additional information regarding copyright ownership.
006     *  The ASF licenses this file to You under the Apache License, Version 2.0
007     *  (the "License"); you may not use this file except in compliance with
008     *  the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     *  Unless required by applicable law or agreed to in writing, software
013     *  distributed under the License is distributed on an "AS IS" BASIS,
014     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     *  See the License for the specific language governing permissions and
016     *  limitations under the License.
017     */
018    package org.apache.geronimo.clustering;
019    
020    import java.util.Map;
021    
022    /**
023     * Represents a clustered session.
024     * <p>
025     * A Session is created by a SessionManager and is uniquely identified by its sessionId. More accurately, this 
026     * sessionId is unique within the set of SessionManagers from which this Session has been sourced. If two Sessions 
027     * have the same sessionId, then a client can be sure that they have been created from two distinct set of 
028     * SessionManagers.
029     * <p>
030     * A Session provides Map like contracts to manipulate state information. State information must be Serializable as
031     * it may be marshalled automatically by the underpinning local SessionManager. At any given point of time, a Session
032     * is uniquely "instantiated" once cluster wide. Also, cluster wide accesses to a given Session are 
033     * ensured to be serialized by the set of SessionManagers from which the Session has been sourced. The interposition
034     * of a ClusteredInvocation between a client and the Session this client would like to access enforces unique
035     * instantiation and access serialization cluster wide for a given Session.
036     *
037     * @version $Rev$ $Date$
038     */
039    public interface Session {
040        
041        /**
042         * Gets the sessionId.
043         * 
044         * @return sessionId.
045         */
046        String getSessionId();
047    
048        /**
049         * Map like contract to manipulate state information.
050         */
051        Object addState(String key, Object value);
052    
053        /**
054         * Map like contract to manipulate state information.
055         */
056        Object getState(String key);
057    
058        /**
059         * Map like contract to manipulate state information.
060         */
061        Object removeState(String key);
062        
063        /**
064         * Map like contract to manipulate state information.
065         * <p>
066         * The returned Map is mutable and is backed by the session.
067         */
068        Map getState();
069        
070        /**
071         * Releases the session.
072         * <p>
073         * When a Session is released, it is released from the underlying set of SessionManagers. In other words, its
074         * sessionId is unknown and its state is permanently lost. After the release of a Session, the behavior of
075         * the other methods is undefined.
076         */
077        void release();
078        
079    }