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.services;
016    
017    import org.apache.tapestry.IComponent;
018    import org.apache.tapestry.IRequestCycle;
019    import org.apache.tapestry.parse.ComponentTemplate;
020    
021    /**
022     * A source of localized HTML templates for components.  
023     * The cache is the means of access for components to load thier templates,
024     * which they need not do until just before rendering.
025     *
026     * <p>The template cache must be able to locate and parse templates as needed.
027     * It may maintain templates in memory.
028     *
029     * @author Howard Ship
030     */
031    
032    public interface TemplateSource
033    {
034        /**
035         *  Name of an {@link org.apache.tapestry.IAsset} of a component that provides the template
036         *  for the asset.  This overrides the default (that the template is in
037         *  the same directory as the specification).  This allows
038         *  pages or component templates to be located properly, relative to static
039         *  assets (such as images and stylesheets).
040         * 
041         *  @since 2.2
042         * 
043         */
044        
045        public static final String TEMPLATE_ASSET_NAME = "$template";
046    
047        /**
048         *  Name of the component parameter that will be automatically bound to
049         *  the HTML tag that is used to insert the component in the parent template.
050         *  If the parent component does not have a template (i.e. it extends 
051         *  AbstractComponent, not BaseComponent), then this parameter is bound to null.
052         * 
053         *  @since 3.0
054         * 
055         */
056        
057        public static final String TEMPLATE_TAG_PARAMETER_NAME = "templateTag";
058        
059        /**
060         *  Locates the template for the component.
061         * 
062         *  @param cycle The request cycle loading the template; this is required
063         *  in some cases when the template is loaded from an {@link org.apache.tapestry.IAsset}.
064         *  @param component The component for which a template should be loaded.
065         *
066         *  @throws org.apache.tapestry.ApplicationRuntimeException if the resource cannot be located or loaded.
067         * 
068         */
069    
070        public ComponentTemplate getTemplate(IRequestCycle cycle, IComponent component);
071    
072    }