001    // Copyright 2009 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    import java.io.IOException;
018    import java.io.ObjectInputStream;
019    
020    /**
021     * A service used when a component or service needs to encode some amount of data on the client as a string. The string
022     * may be a query parameter, hidden form field, or a portion of a URL.  The default implementation converts the object
023     * output stream into a Base64 string.
024     *
025     * @since 5.1.0.1
026     */
027    public interface ClientDataEncoder
028    {
029        /**
030         * Creates a sink for client data.  The sink provides an output stream and ultimately, a string representation of
031         * the data sent to the stream.
032         *
033         * @return a new sink
034         */
035        ClientDataSink createSink();
036    
037        /**
038         * Decodes data previously obtained from {@link ClientDataSink#getClientData()}.
039         *
040         * @param clientData encoded client data
041         * @return stream of decoded data
042         */
043        ObjectInputStream decodeClientData(String clientData) throws IOException;
044    
045        /**
046         * Decoes client data obtained via {@link ClientDataSink#getEncodedClientData()}.
047         *
048         * @param clientData URLEncoded client data
049         * @return stream of objects
050         * @throws IOException
051         * @since 5.1.0.4
052         */
053        ObjectInputStream decodeEncodedClientData(String clientData) throws IOException;
054    }