001    // Copyright 2006, 2007, 2008, 2009, 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    
015    package org.apache.tapestry5.internal.services;
016    
017    import org.apache.tapestry5.ComponentResourcesCommon;
018    import org.apache.tapestry5.internal.structure.Page;
019    import org.apache.tapestry5.services.pageload.ComponentResourceSelector;
020    
021    /**
022     * Instantiates a fully loaded, configured instance of a Tapestry page. This is a recursive process, since part of
023     * loading a page is to load the page elements for the page, many of which are components. Further, in some cases, the
024     * full component tree is not identified until after each component's template is loaded. Pages are instantiated once
025     * for each {@link ComponentResourceSelector} (prior to 5.3, once for each locale; prior to 5.1, for locale and pooled).
026     * 
027     * @see RequestPageCache
028     */
029    public interface PageLoader
030    {
031        /**
032         * Loads the page for the indicated selector.
033         * 
034         * @param pageName
035         *            the <em>canonicalized</em> logical name of the page, which will be made available via
036         *            {@link Page#getName()} and {@link ComponentResourcesCommon#getPageName()} (for any component within
037         *            the page).
038         * @param selector
039         *            Encapsulates the locale and other information used to select the component's
040         *            template and message catalog resources.
041         */
042        Page loadPage(String pageName, ComponentResourceSelector selector);
043    }