001    /*
002     * Copyright 2005 Stephen McConnell
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
013     * implied.
014     *
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package net.dpml.transit;
020    
021    import java.io.IOException;
022    
023    import net.dpml.lang.UnknownKeyException;
024    
025    /**
026     * A interface supporting access to pluggable content handlers.
027     *
028     * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
029     * @version 1.0.2
030     */
031    public interface LayoutRegistry
032    {
033       /**
034        * Constrant layout plugin key.
035        */
036        public static final String LAYOUT_HANDLER_PLUGIN_KEY = "dpml.transit.layout.plugin";
037    
038       /**
039        * Return a location resolver capable for supporting the supplied id. If
040        * a handler is available the handler is returned otherwise the returned
041        * value is null.
042        *
043        * @param id the layout identifier
044        * @return the location resolver or null if not available
045        * @exception UnknownKeyException if the key is not recognized
046        * @exception IOException if an IO error occurs
047        */
048        Layout getLayout( final String id ) throws UnknownKeyException, IOException;
049    }