    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
    015    package org.apache.tapestry5.runtime;
    016
    017    import org.apache.tapestry5.ComponentResources;
    018
    019    /**
    020     * A stateful object that manages the process of rendering a page. Rending a page in Tapestry is based on a command
    021     * queue.
    022     */
    023    public interface RenderQueue
    024    {
    025        /**
    026         * Adds the new command to the front of the queue.
    027         */
    028        void push(RenderCommand command);
    029
    030        /**
    031         * Indicates that a component is starting its render. A stack of active components is used for exception reporting.
    032         *
    033         * @param resources
    034         *            identifies the component that is rendering
    035         */
    036        void startComponent(ComponentResources resources);
    037
    038        /**
    039         * Corresponds to {@link #startComponent(ComponentResources)}, used to denote when the most recently started
    040         * component finishes
    041         * rendering.
    042         */
    043        void endComponent();
    044    }