001    // Copyright 2012 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.runtime;
016    
017    /**
018     * Defines a way for different aspects of a page to add callbacks for important lifecycle events.
019     *
020     * @see org.apache.tapestry5.ComponentResources#getPageLifecycleCallbackHub()
021     * @since 5.3.4
022     */
023    public interface PageLifecycleCallbackHub
024    {
025        /**
026         * Adds a callback for when the page is first loaded.  Callbacks are invoked in the order they
027         * are added to the page. They are invoked once and then discarded.
028         *
029         * @param callback
030         *         invoked once, when page is first loaded
031         * @since 5.3.4
032         */
033        void addPageLoadedCallback(Runnable callback);
034    
035        /**
036         * Adds a callback for when the page is attached to the request.
037         *
038         * @param callback
039         * @since 5.3.4
040         */
041        void addPageAttachedCallback(Runnable callback);
042    
043        /**
044         * Adds a callback for when the page is detached from the request.
045         *
046         * @param callback
047         * @since 5.3.4
048         */
049        void addPageDetachedCallback(Runnable callback);
050    
051        /**
052         * Adds a verify callback, which is allowed while the page is loading. Such callbacks are invoked once,
053         * after the page has been loaded successfully, and are then discarded. This was added specifically to ensure that components
054         * only verify that required parameters are bound after all components and mixins of the page have had a chance
055         * to initialize.
056         *
057         * @param callback
058         *         to be invoked after page loaded
059         * @since 5.3
060         */
061        void addVerifyCallback(Runnable callback);
062    
063        /**
064         * A reset occurs when a request for a page arrives that did not originate on the same page. This gives the application a chance to reset the state of the page.
065         *
066         * @param callback
067         *         invoked when a page is activated by link from some other page.
068         */
069        void addResetCallback(Runnable callback);
070    }