001/*
002 *  Copyright 2023 Anyware Services
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.ametys.core.util;
017
018import java.util.Optional;
019
020/**
021 * A session provider allow to retrieve a value stored in session.
022 * This interface allow for implementation able to handle case where the session doesn't exists
023 */
024public interface SessionAttributeProvider
025{
026    /** The avalon role */
027    public static final String ROLE = SessionAttributeProvider.class.getName();
028    
029    /**
030     * Retrieve a stored session attribute from the current request.
031     * 
032     * The stored attribute must be a String or the behavior is undefined and may throw an exception
033     * @param attributeName the name of the attribute
034     * @return the value of the attribute or empty if no value are stored for the given attribute
035     */
036    public Optional<Object> getSessionAttribute(String attributeName);
037}