001// Copyright 2010 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.tapestry5;
016
017import java.io.IOException;
018
019import org.apache.tapestry5.annotations.Environmental;
020import org.apache.tapestry5.services.ComponentEventResultProcessor;
021import org.apache.tapestry5.services.Traditional;
022
023/**
024 * Extends {@link ComponentEventCallback} with a way to determine if the underlying event has been aborted
025 * due to a some event returning an acceptable, non-null value. The standard implementation of this
026 * is a wrapper around either the {@linkplain Traditional traditional} or
027 * {@linkplain org.apache.tapestry5.services.Ajax ajax} versions of the {@link ComponentEventResultProcessor}
028 * service, i.e., they allow for a navigational result.
029 * <p>
030 * Instances of this are made available via the {@link Environmental} annotation.
031 * 
032 * @since 5.2.0
033 */
034public interface TrackableComponentEventCallback<T> extends ComponentEventCallback<T>
035{
036    /**
037     * Returns true if a return value from an event handler method was processed.
038     */
039    boolean isAborted();
040
041    /**
042     * If processing a return value threw an IOException, invoking this method will rethrow it.
043     */
044    void rethrow() throws IOException;
045}