Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.rya.streams.querymanager; import static java.util.Objects.requireNonNull; import java.io.InputStream; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.concurrent.TimeUnit; import javax.xml.bind.JAXBException; import org.apache.commons.daemon.Daemon; import org.apache.commons.daemon.DaemonContext; import org.apache.commons.daemon.DaemonInitException; import org.apache.rya.streams.kafka.KafkaStreamsFactory; import org.apache.rya.streams.kafka.SingleThreadKafkaStreamsFactory; import org.apache.rya.streams.kafka.interactor.CreateKafkaTopic; import org.apache.rya.streams.querymanager.kafka.KafkaQueryChangeLogSource; import org.apache.rya.streams.querymanager.kafka.LocalQueryExecutor; import org.apache.rya.streams.querymanager.xml.Kafka; import org.apache.rya.streams.querymanager.xml.QueryManagerConfig; import org.apache.rya.streams.querymanager.xml.QueryManagerConfig.PerformanceTunning.QueryChanngeLogDiscoveryPeriod; import org.apache.rya.streams.querymanager.xml.QueryManagerConfigUnmarshaller; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xml.sax.SAXException; import com.beust.jcommander.JCommander; import com.beust.jcommander.Parameter; import com.beust.jcommander.ParameterException; import com.google.common.util.concurrent.AbstractScheduledService.Scheduler; import edu.umd.cs.findbugs.annotations.DefaultAnnotation; import edu.umd.cs.findbugs.annotations.NonNull; /** * JSVC integration code for a {@link QueryManager} to be used as a non-Windows daemon. */ @DefaultAnnotation(NonNull.class) public class QueryManagerDaemon implements Daemon { private static final Logger log = LoggerFactory.getLogger(QueryManagerDaemon.class); /** * The default configuration file's path for the application. */ private static final Path DEFAULT_CONFIGURATION_PATH = Paths.get("config/configuration.xml"); /** * Command line parameters that are used by all commands that interact with Kafka. */ class DaemonParameters { @Parameter(names = { "--config", "-c" }, required = false, description = "The path to the application's configuration file.") public String config; } private QueryManager manager = null; @Override public void init(final DaemonContext context) throws DaemonInitException, Exception { requireNonNull(context); // Parse the command line arguments for the configuration file to use. final String[] args = context.getArguments(); final DaemonParameters params = new DaemonParameters(); try { new JCommander(params).parse(args); } catch (final ParameterException e) { throw new DaemonInitException("Unable to parse the command line arguments.", e); } final Path configFile = params.config != null ? Paths.get(params.config) : DEFAULT_CONFIGURATION_PATH; log.info("Loading the following configuration file: " + configFile); // Unmarshall the configuration file into an object. final QueryManagerConfig config; try (final InputStream stream = Files.newInputStream(configFile)) { config = QueryManagerConfigUnmarshaller.unmarshall(stream); } catch (final JAXBException | SAXException e) { throw new DaemonInitException("Unable to marshall the configuration XML file: " + configFile, e); } // Read the source polling period from the configuration. final QueryChanngeLogDiscoveryPeriod periodConfig = config.getPerformanceTunning() .getQueryChanngeLogDiscoveryPeriod(); final long period = periodConfig.getValue().longValue(); final TimeUnit units = TimeUnit.valueOf(periodConfig.getUnits().toString()); log.info("Query Change Log Polling Period: " + period + " " + units); final Scheduler scheduler = Scheduler.newFixedRateSchedule(0, period, units); // Initialize a QueryChangeLogSource. final Kafka kafka = config.getQueryChangeLogSource().getKafka(); log.info("Kafka Source: " + kafka.getHostname() + ":" + kafka.getPort()); final QueryChangeLogSource source = new KafkaQueryChangeLogSource(kafka.getHostname(), kafka.getPort(), scheduler); // Initialize a QueryExecutor. final String zookeeperServers = config.getQueryExecutor().getLocalKafkaStreams().getZookeepers(); final KafkaStreamsFactory streamsFactory = new SingleThreadKafkaStreamsFactory( kafka.getHostname() + ":" + kafka.getPort()); final QueryExecutor queryExecutor = new LocalQueryExecutor(new CreateKafkaTopic(zookeeperServers), streamsFactory); // Initialize the QueryManager using the configured resources. manager = new QueryManager(queryExecutor, source, period, units); } @Override public void start() throws Exception { log.info("Starting the Rya Streams Query Manager Daemon."); manager.startAndWait(); } @Override public void stop() throws Exception { log.info("Stopping the Rya Streams Query Manager Daemon."); manager.stopAndWait(); } @Override public void destroy() { } }