001// Copyright 2006, 2008, 2011 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.tapestry5.internal.services; 016 017import org.apache.tapestry5.internal.parser.ComponentTemplate; 018import org.apache.tapestry5.model.ComponentModel; 019import org.apache.tapestry5.services.InvalidationEventHub; 020import org.apache.tapestry5.services.pageload.ComponentResourceSelector; 021 022/** 023 * Provides access to cached {@link org.apache.tapestry5.internal.parser.ComponentTemplate}s. The source acts as a 024 * invalidation event hub, and will broadcast invalidation events when any loaded template resource changes. The 025 * listener for these invalidation events is the page source, which stores cached page instances. 026 * <p/> 027 * Any search for a template will end with success (a non-null template), but the template returned may be the 028 * {@link ComponentTemplate#isMissing() missing template}. 029 */ 030public interface ComponentTemplateSource 031{ 032 /** 033 * Provides access to a template. The template will be parsed as necessary. If no template for the exact component 034 * is found, then the template for the component's parent is returned. In this way, it is possible for a component 035 * to extend the behavior of its super-class without duplicating the super-class component's template. 036 * <p/> 037 * In some cases, the empty template will be returned. 038 * 039 * @param componentModel 040 * model for the component whose template is to be accessed 041 * @param selector 042 * defines locale and other information needed to locate template 043 * @return the cached template instance 044 */ 045 ComponentTemplate getTemplate(ComponentModel componentModel, ComponentResourceSelector selector); 046 047 /** 048 * Event hub used to notify listeners that underlying component template files have changed. 049 * 050 * @see org.apache.tapestry5.services.ComponentTemplates 051 * @since 5.1.0.0 052 */ 053 InvalidationEventHub getInvalidationEventHub(); 054}