001    // Copyright 2006 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    
015    package org.apache.tapestry5.services;
016    
017    /**
018     * Represents a previously stored change to a persistent field, within the context of a particular page of the
019     * application.
020     */
021    public interface PersistentFieldChange
022    {
023        /**
024         * Returns the nested id of the component, or the empty string for the page's root component.
025         */
026        String getComponentId();
027    
028        /**
029         * Returns the name of the field for which a change was recorded.
030         */
031        String getFieldName();
032    
033        /**
034         * Returns the new value for the field (which may be null).
035         */
036        Object getValue();
037    }