CamelStepListener.java

/*
 * Copyright (c) 2016 Red Hat, Inc. and/or its affiliates.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * Cheng Fang - Initial API and implementation
 */

package org.jberet.camel;

import javax.batch.api.listener.StepListener;
import javax.batch.runtime.StepExecution;
import javax.batch.runtime.context.StepContext;
import javax.inject.Inject;
import javax.inject.Named;

import static org.jberet.camel.EventType.AFTER_STEP;
import static org.jberet.camel.EventType.BEFORE_STEP;

/**
 * An implementation of {@code javax.batch.api.listener.StepListener} that sends
 * step execution events to a Camel endpoint. Two types of events are sent:
 * <ul>
 *     <li>{@value org.jberet.camel.EventType#BEFORE_STEP}: sent before a step execution
 *     <li>{@value org.jberet.camel.EventType#AFTER_STEP}: sent after a step execution
 * </ul>
 * The body of the message sent is the current {@code StepExecution}.
 * Each message also contains a header to indicate the event type:
 * its key is {@value org.jberet.camel.EventType#KEY}, and value is either
 * {@value org.jberet.camel.EventType#BEFORE_STEP} or
 * {@value org.jberet.camel.EventType#AFTER_STEP}.
 * <p>
 * The target Camel endpoint is configured through batch property
 * {@code endpoint} in job XML. For example,
 * <pre>
 * <job id="camelStepListenerTest" xmlns="http://xmlns.jcp.org/xml/ns/javaee" version="1.0">
 *   <step id="camelStepListenerTest.step1">
 *     <listeners>
 *       <listener ref="camelStepListener">
 *         <properties>
 *           <property name="endpoint" value="#{jobParameters['endpoint']}"/>
 *         </properties>
 *       </listener>
 *     </listeners>
 *     ... ...
 *   </step>
 * </job>
 * </pre>
 *
 * @see CamelJobListener
 * @see CamelChunkListener
 * @since 1.3.0
 */
@Named
public class CamelStepListener extends CamelListenerBase implements StepListener {
    /**
     * Injection of {@code javax.batch.runtime.context.StepContext} by batch
     * runtime.
     */
    @Inject
    protected StepContext stepContext;

    /**
     * {@inheritDoc}
     * <p>
     * This method sends {@value org.jberet.camel.EventType#BEFORE_STEP}
     * event to the configured Camel endpoint. The message contains a header:
     * <pre>
     *     {@value org.jberet.camel.EventType#KEY}={@value org.jberet.camel.EventType#BEFORE_STEP}
     * </pre>
     * , and the message body is the current {@code javax.batch.runtime.StepExecution}.
     *
     * @throws Exception
     */
    @Override
    public void beforeStep() throws Exception {
        sendBodyAndHeader(BEFORE_STEP);
    }

    /**
     * {@inheritDoc}
     * <p>
     * This method sends {@value org.jberet.camel.EventType#AFTER_STEP}
     * event to the configured Camel endpoint. The message contains a header:
     * <pre>
     *     {@value org.jberet.camel.EventType#KEY}={@value org.jberet.camel.EventType#AFTER_STEP}
     * </pre>
     * , and the message body is the current {@code javax.batch.runtime.StepExecution}.
     *
     * @throws Exception
     */
    @Override
    public void afterStep() throws Exception {
        sendBodyAndHeader(AFTER_STEP);
    }

    /**
     * Sends the step execution event message to the configured Camel endpoint.
     * The message has the current {@code StepExecution} as the body, and
     * a header to indicate the event type.
     *
     * @param headerValue either {@value org.jberet.camel.EventType#BEFORE_STEP}
     *                    or {@value org.jberet.camel.EventType#AFTER_STEP}
     */
    protected void sendBodyAndHeader(final String headerValue) {
        final long jobExecutionId = jobContext.getExecutionId();
        final long stepExecutionId = stepContext.getStepExecutionId();
        StepExecution stepExecution = null;
        for (final StepExecution e : jobOperator.getStepExecutions(jobExecutionId)) {
            if (stepExecutionId == e.getStepExecutionId()) {
                stepExecution = e;
                break;
            }
        }

        producerTemplate.sendBodyAndHeader(endpoint, stepExecution, EventType.KEY, headerValue);
    }
}