001// Copyright 2006, 2008 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.services;
016
017import javax.servlet.http.HttpSession;
018
019import org.apache.tapestry5.OptimizedSessionPersistedObject;
020import org.apache.tapestry5.annotations.ImmutableSessionPersistedObject;
021import org.apache.tapestry5.internal.services.OptimizedSessionPersistedObjectAnalyzer;
022
023import java.util.List;
024
025/**
026 * Generic version of {@link HttpSession}, used to bridge the gaps between the Servlet API and the Portlet API.
027 */
028public interface Session
029{
030    /**
031     * Returns a list of the names of all attributes stored in the session. The names are returned sorted
032     * alphabetically.
033     */
034    List<String> getAttributeNames();
035
036    /**
037     * Returns a list of the names of all attributes stored in the session whose name has the provided prefix. The names
038     * are returned in alphabetical order.
039     */
040    List<String> getAttributeNames(String prefix);
041
042    /**
043     * Returns the value previously stored in the session.
044     */
045    Object getAttribute(String name);
046
047    /**
048     * Sets the value of an attribute. If the value is null, then the attribute is deleted.
049     */
050    void setAttribute(String name, Object value);
051
052    /**
053     * Returns the maximum time interval, in seconds, that the servlet container will keep this session open between
054     * client accesses. After this interval, the servlet container will invalidate the session. The maximum time
055     * interval can be set with the setMaxInactiveInterval method. A negative time indicates the session should never
056     * timeout.
057     */
058    int getMaxInactiveInterval();
059
060    /**
061     * Specifies the time, in seconds, between client requests before the servlet container will invalidate this
062     * session. A negative time indicates the session should never timeout.
063     */
064    void setMaxInactiveInterval(int seconds);
065
066    /**
067     * Invalidates this session then unbinds any objects bound to it.
068     * 
069     * @throws IllegalStateException
070     *             if this method is called on an already invalidated session
071     */
072    void invalidate();
073
074    /**
075     * Checks to see if the session has been invalidated. Note: since 5.3 this will also catch calls to
076     * {@link javax.servlet.http.HttpSession#invalidate()}.
077     * 
078     * @since 5.1.0.0
079     */
080    boolean isInvalidated();
081
082    /**
083     * Re-stores dirty objects back into the session. This is necessary to support clustering, because (in most
084     * application servers) session objects are only broadcast around the cluster from setAttribute(). If a mutable
085     * session object is read and changed, those changes will be limited to a single server in the cluster, which can
086     * cause confusing application failures in the event of a failover. Does nothing if there are no changes, or
087     * the session has been invalidated.
088     * 
089     * @see OptimizedSessionPersistedObject
090     * @see OptimizedSessionPersistedObjectAnalyzer
091     * @see ImmutableSessionPersistedObject
092     * @since 5.1.0.0
093     */
094    void restoreDirtyObjects();
095}