001    // Copyright 2004, 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.engine;
016    
017    /**
018     * Encapsulates the logic for encoding and decoding service requests.
019     * 
020     * @author Howard M. Lewis Ship
021     * @since 4.0
022     */
023    public interface ServiceEncoder
024    {
025        /**
026         * Invoked by the {@link org.apache.tapestry.services.LinkFactory} to encode the request.
027         * Encoding is the process of modifying the encoding object to represent the same data in a
028         * different format; the canoncial example is to replace the
029         * {@link org.apache.tapestry.services.ServiceConstants#PAGE}and
030         * {@link org.apache.tapestry.services.ServiceConstants#SERVICE}query parameters with a servlet
031         * path (i.e., "/Home.html", if the ".html" extension is mapped to the page service).
032         * <p>
033         * The {@link org.apache.tapestry.services.LinkFactory}&nbsp;iterates over a collection of
034         * encoders, stopping once the ServiceRequestEncoding is modified in any way.
035         */
036    
037        public void encode(ServiceEncoding encoding);
038    
039        /**
040         * Invoked to decode a request. The encoder is responsible for recognizing a request it may have
041         * encoded, and for restoring any query parameters is may have removed.
042         */
043    
044        public void decode(ServiceEncoding encoding);
045    }