001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.spi;
018
019import org.apache.camel.CamelContextAware;
020import org.apache.camel.Consumer;
021import org.apache.camel.ShutdownableService;
022
023/**
024 * A pluggable scheduler for {@link org.apache.camel.impl.ScheduledPollConsumer} consumers.
025 * <p/>
026 * The default implementation {@link org.apache.camel.impl.DefaultScheduledPollConsumerScheduler} is
027 * using the {@link java.util.concurrent.ScheduledExecutorService} from the JDK to schedule and run the poll task.
028 * <p/>
029 * An alternative implementation is in <tt>camel-quartz2</tt> component that allows to use CRON expression
030 * to define when the scheduler should run.
031 */
032public interface ScheduledPollConsumerScheduler extends ShutdownableService, CamelContextAware {
033
034    /**
035     * Initializes this {@link ScheduledPollConsumerScheduler} with the associated {@link Consumer}.
036     *
037     * @param consumer the consumer.
038     */
039    void onInit(Consumer consumer);
040
041    /**
042     * Schedules the task to run.
043     *
044     * @param task the task to run.
045     */
046    void scheduleTask(Runnable task);
047
048    /**
049     * Attempts to unschedules the last task which was scheduled.
050     * <p/>
051     * An implementation may not implement this method.
052     */
053    void unscheduleTask();
054
055    /**
056     * Starts the scheduler.
057     * <p/>
058     * If the scheduler is already started, then this is a noop method call.
059     */
060    void startScheduler();
061
062    /**
063     * Whether the scheduler has been started.
064     *
065     * @return <tt>true</tt> if started, <tt>false</tt> otherwise.
066     */
067    boolean isSchedulerStarted();
068
069}