001// Copyright 2004, 2005 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
015package org.apache.tapestry.callback;
016
017import java.io.Serializable;
018
019import org.apache.tapestry.IRequestCycle;
020
021/**
022 *  Defines a callback, an object which is used to invoke or reinvoke a method
023 *  on an object or component in a later request cycle.  This is used to
024 *  allow certain operations (say, submitting an order) to defer to other processes
025 *  (say, logging in and/or registerring).
026 *
027 *  <p>Callbacks must be {@link Serializable}, to ensure that they can be stored
028 *  between request cycles.
029 *
030 *  @author Howard Lewis Ship
031 *  @since 0.2.9
032 *
033 **/
034
035public interface ICallback extends Serializable
036{
037    /**
038     *  Performs the call back.  Typical implementation will locate a particular
039     *  page or component and invoke a method upon it, or 
040     *  invoke a method on the {@link IRequestCycle cycle}.
041     *
042     **/
043
044    public void performCallback(IRequestCycle cycle);
045}