Java tutorial
/** * eobjects.org AnalyzerBeans * Copyright (C) 2010 eobjects.org * * This copyrighted material is made available to anyone wishing to use, modify, * copy, or redistribute it subject to the terms and conditions of the GNU * Lesser General Public License, as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License * for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this distribution; if not, write to: * Free Software Foundation, Inc. * 51 Franklin Street, Fifth Floor * Boston, MA 02110-1301 USA */ package org.eobjects.analyzer.cluster.http; import java.io.InputStream; import java.util.LinkedList; import java.util.List; import org.apache.commons.io.output.ByteArrayOutputStream; import org.apache.http.HttpResponse; import org.apache.http.StatusLine; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.ByteArrayEntity; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.impl.conn.PoolingClientConnectionManager; import org.eobjects.analyzer.cluster.ClusterManager; import org.eobjects.analyzer.cluster.DistributedJobContext; import org.eobjects.analyzer.cluster.FixedDivisionsCountJobDivisionManager; import org.eobjects.analyzer.cluster.JobDivisionManager; import org.eobjects.analyzer.cluster.LazyRefAnalysisResultFuture; import org.eobjects.analyzer.job.AnalysisJob; import org.eobjects.analyzer.job.JaxbJobWriter; import org.eobjects.analyzer.job.runner.AnalysisResultFuture; import org.eobjects.analyzer.result.AnalysisResult; import org.eobjects.analyzer.util.ChangeAwareObjectInputStream; import org.eobjects.metamodel.util.Action; import org.eobjects.metamodel.util.FileHelper; import org.eobjects.metamodel.util.LazyRef; /** * A cluster manager that uses HTTP servlet transport to communicate between * nodes. */ public class HttpClusterManager implements ClusterManager { private final HttpClient _httpClient; private final List<String> _slaveEndpoints; /** * Creates a new HTTP cluster manager * * @param slaveEndpoints * the endpoint URLs of the slaves */ public HttpClusterManager(List<String> slaveEndpoints) { this(new DefaultHttpClient(new PoolingClientConnectionManager()), slaveEndpoints); } /** * Create a new HTTP cluster manager * * @param httpClient * http client to use for invoking slave endpoints. Must be * capable of executing multiple requests at the same time (see * {@link PoolingClientConnectionManager}). * @param slaveEndpoints * the endpoint URLs of the slaves */ public HttpClusterManager(HttpClient httpClient, List<String> slaveEndpoints) { _httpClient = httpClient; _slaveEndpoints = slaveEndpoints; } @Override public JobDivisionManager getJobDivisionManager() { return new FixedDivisionsCountJobDivisionManager(_slaveEndpoints.size()); } @Override public AnalysisResultFuture dispatchJob(AnalysisJob job, DistributedJobContext context) throws Exception { // determine endpoint url final int index = context.getJobDivisionIndex(); final String slaveEndpoint = _slaveEndpoints.get(index); // write the job as XML final JaxbJobWriter jobWriter = new JaxbJobWriter(context.getMasterConfiguration()); final ByteArrayOutputStream baos = new ByteArrayOutputStream(); jobWriter.write(job, baos); final byte[] bytes = baos.toByteArray(); // send the request in another thread final List<Throwable> errors = new LinkedList<Throwable>(); final LazyRef<AnalysisResult> resultRef = sendRequest(slaveEndpoint, bytes, errors); resultRef.requestLoad(new Action<Throwable>() { @Override public void run(Throwable error) throws Exception { errors.add(error); } }); return new LazyRefAnalysisResultFuture(resultRef, errors); } private LazyRef<AnalysisResult> sendRequest(final String slaveEndpoint, final byte[] bytes, final List<Throwable> errors) { return new LazyRef<AnalysisResult>() { @Override protected AnalysisResult fetch() throws Throwable { // send the HTTP request final HttpPost request = new HttpPost(slaveEndpoint); request.setEntity(new ByteArrayEntity(bytes)); final HttpResponse response = _httpClient.execute(request); // handle the response final StatusLine statusLine = response.getStatusLine(); if (statusLine.getStatusCode() != 200) { throw new IllegalStateException("Slave server responded with an error: " + statusLine.getReasonPhrase() + " (" + statusLine.getStatusCode() + ")"); } final InputStream inputStream = response.getEntity().getContent(); try { AnalysisResult result = readResult(inputStream, errors); return result; } finally { FileHelper.safeClose(inputStream); } } }; } protected AnalysisResult readResult(InputStream inputStream, List<Throwable> errors) throws Exception { final ChangeAwareObjectInputStream changeAwareObjectInputStream = new ChangeAwareObjectInputStream( inputStream); final Object object = changeAwareObjectInputStream.readObject(); changeAwareObjectInputStream.close(); if (object instanceof AnalysisResult) { // response carries a result return (AnalysisResult) object; } else if (object instanceof List) { // response carries a list of errors @SuppressWarnings("unchecked") List<Throwable> slaveErrors = (List<Throwable>) object; errors.addAll(slaveErrors); return null; } else { throw new IllegalStateException("Unexpected response payload: " + object); } } }