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
015package org.apache.tapestry.engine;
016
017import java.util.Locale;
018
019import org.apache.tapestry.IComponent;
020import org.apache.tapestry.IRequestCycle;
021import org.apache.tapestry.parse.ComponentTemplate;
022
023/**
024 *  Acts as a delegate to the {@link org.apache.tapestry.services.TemplateSource}, 
025 *  providing access to page and component templates after the normal search mechanisms have failed.
026 * 
027 *  <p>
028 *  The delegate must be threadsafe.
029 *
030 *  @author Howard Lewis Ship
031 *  @since 3.0
032 *  @see org.apache.tapestry.services.impl.TemplateSourceImpl
033 * 
034 **/
035
036public interface ITemplateSourceDelegate
037{
038    /**
039     *  Invoked by the {@link ITemplateSource} when a template can't be found
040     *  by normal means (i.e., in the normal locations).  This method
041     *  should find the template.  The result may be null.  The delegate
042     *  is responsible for caching the result.
043     * 
044     *  @param cycle for access to Tapestry and Servlet API objects
045     *  @param component component (or page) for which a template is needed
046     *  @param locale the desired locale for the template
047     * 
048     **/
049
050    public ComponentTemplate findTemplate(IRequestCycle cycle, IComponent component, Locale locale);
051}