001    // Copyright 2005 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.tapestry.record;
016    
017    import java.util.List;
018    
019    /**
020     * Responsible for encoding {@link org.apache.tapestry.record.PropertyChange}s into and out of plain
021     * strings.
022     * 
023     * @author Howard M. Lewis Ship
024     * @since 4.0
025     */
026    public interface PersistentPropertyDataEncoder
027    {
028        /**
029         * Encodes a (possibly empty) list of {@link PropertyChange}s into a string representation that
030         * can later be decoded.
031         * 
032         * @returns encoded string (possibly empty, but not null)
033         */
034        public String encodePageChanges(List changes);
035    
036        /**
037         * Takes a string with an encoded set of page changes, and converts it back into a list of
038         * {@link org.apache.tapestry.record.PropertyChange}s.
039         */
040    
041        public List decodePageChanges(String encoded);
042    
043    }