    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.internal.structure.Page;
    018    import org.apache.tapestry5.runtime.PageLifecycleListener;
    019
    020    /**
    021     * Per-thread service that caches page instances for the duration of the request, and is also responsible for tracking
    022     * the active page (the page which will ultimately render the response).
    023     * <p/>
    024     * Since {@link org.apache.tapestry5.internal.structure.Page} is internal, most user-code should use the
    025     * {@link org.apache.tapestry5.services.ComponentSource} service instead.
    026     * <p>
    027     * Starting in 5.2, page instances are shared (with externalized mutable state), not pooled, but the cache is still
    028     * useful for managing the page's {@linkplain PageLifecycleListener lifecycle}.
    029     */
    030    public interface RequestPageCache
    031    {
    032        /**
    033         * Gets the page via its page name, in the current locale. The logical page name is resolved to a class name, which
    034         * is used to obtain the page (from the page pool). Note that under certain circumstances, a page may have multiple
    035         * names (even beyond simple case-insensitivity), and RequestPageCache caches correctly.
    036         *
    037         * @param pageName
    038         *            the name of the page to retrieve (this is the logical page name, not the fully qualified class
    039         *            name)
    040         * @return a page instance reserved for this request
    041         * @throws IllegalArgumentException
    042         *             if the name can not be resolved to a page instance
    043         */
    044        Page get(String pageName);
    045    }