/*

 Wotonomy: OpenStep design patterns for pure Java applications.

 Copyright (C) 2000 Blacksmith, Inc.

 This library is free software; you can redistribute it and/or

 modify it under the terms of the GNU Lesser General Public

 License as published by the Free Software Foundation; either

 version 2.1 of the License, or (at your option) any later version.

 This library is distributed in the hope that it will be useful,

 but WITHOUT ANY WARRANTY; without even the implied warranty of

 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public

 License along with this library; if not, see http://www.gnu.org

 */

 package net.wotonomy.web;

 import java.io.Serializable;

 import net.wotonomy.foundation.NSDictionary;

 /**

 * This class represents a static or dynamic portion of the 

 * content returned to a request.  Each request walks a tree

 * of WOElements to generate a response.

 *

 * @author michael@mpowers.net

 * @author $Author: cgruber $

 * @version $Revision: 905 $

 */

 public abstract class WOElement implements WOActionResults, Serializable

 {

         NSDictionary associations;

         /**

         * Default constructor.  Performs necessary initialization.

         */

         public WOElement()

         {

         }

         /**

         * This method is called to retrieve user-entered data from

         * the request.  WOElements should retrieve data from the 

         * request based on their elementID and set values in the 

         * context's current WOComponent, typically those values that

         * are associated with the element in the binding.  This 

         * implementation does nothing.

         */

     public void takeValuesFromRequest (WORequest aRequest, WOContext aContext)

     {

             // does nothing

     }

     /**

     * This method is called on all objects and elements of the 

     * application until a non-null value is returned.

     * WOElements should first check to see if they are the

     * target of an action by checking the WOContext's senderID

     * to see if it matches this element's elementID.  

     * If this element is the target, it should perform an 

     * appropriate action on the context's current WOComponent,

     * usually the action specified in the binding, and return

     * the result of that action.  This implementation returns null.

     */

     public WOActionResults invokeAction (WORequest aRequest, WOContext aContext)

     {

             return null;

     }

     /**

     * This method is called on all elements of the content tree

     * to build a response to a user request.  The message should 

     * be forwarded to any child elements so that the entire tree

     * is traversed.  This implementation does nothing.

     */

     public void appendToResponse (WOResponse aResponse, WOContext aContext)

     {

             // does nothing

     }

     /**

     * Package access only.  Called to initialize the component with 

     * the proper context before the start of the request-response cycle.

     * If the context has a current component, that component becomes

     * this component's parent.

     */

     void ensureAwakeInContext (WOContext aContext)

     {

         // does nothing

     }

 }