    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.annotations;
    014
    015import static java.lang.annotation.RetentionPolicy.RUNTIME;
    016import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.COMPONENT;
    017import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.PAGE;
    018
    019import java.lang.annotation.Documented;
    020import java.lang.annotation.ElementType;
    021import java.lang.annotation.Retention;
    022import java.lang.annotation.Target;
    023
    024import org.apache.tapestry5.ioc.annotations.UseWith;
    025
    026/**
    027 * <p>
    028 * Marks an event handler method to be published as an event to be called in JavaScript
    029 * through the <code>t5/core/ajax</code> function when the <code>options</code>
    030 * parameter has an <code>element</code> attribute.
    031 * </p>
    032 *
    033 * <p>
    034 * The logic for obtaining the URL is actually located implemented in the
    035 * <code>t5/core/dom.getEventUrl(eventName, element)</code> function.
    036 * </p>
    037 *
    038 * <p>
    039 * The event information is stored in JSON format inside the
    040 * {@value org.apache.tapestry5.TapestryConstants#COMPONENT_EVENTS_ATTRIBUTE_NAME} attribute.
    041 * </p>
    042 *
    043 * <p>
    044 * When used in a component method, the component must render at least one element,
    045 * and that's what gets the
    046 * {@value org.apache.tapestry5.TapestryConstants#COMPONENT_EVENTS_ATTRIBUTE_NAME} attribute above.
    047 * If it doesn't, an exception will be thrown.
    048 * </p>
    049 *
    050 * <p>
    051 * When used in a page method, the page must render an &lt;body&gt; element. If it doesn't,
    052 * an exception will be thrown.
    053 * </p>
    054 *
    055 * @since 5.4.2
    056 * @see <a href="https://tapestry.apache.org/ajax-and-zones.html#AjaxandZones-Invokingserver-sideeventhandlermethodsfromJavaScript">Invoking server-side event handler methods from JavaScript</a>
    057 */
    058@Target(ElementType.METHOD)
    059@Retention(RUNTIME)
    060@Documented
    061@UseWith({ COMPONENT, PAGE })
    062public @interface PublishEvent
    063{
    064}