Java tutorial
/* * Copyright (c) 2009, MediaEvent Services GmbH & Co. KG * http://mediaeventservices.com * * This file is part of Marbles. * * Marbles is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Marbles 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Marbles. If not, see <http://www.gnu.org/licenses/>. * */ package de.fuberlin.wiwiss.marbles; import java.io.BufferedReader; import java.io.File; import java.io.FileReader; import java.io.FilenameFilter; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.io.StringWriter; import java.net.URL; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.servlet.ServletConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import org.apache.commons.httpclient.URIException; import org.apache.log4j.Level; import org.apache.log4j.Logger; import org.openrdf.model.Resource; import org.openrdf.model.URI; import org.openrdf.model.ValueFactory; import org.openrdf.model.impl.URIImpl; import org.openrdf.query.GraphQuery; import org.openrdf.query.MalformedQueryException; import org.openrdf.query.Query; import org.openrdf.query.QueryLanguage; import org.openrdf.query.TupleQuery; import org.openrdf.query.resultio.sparqlxml.SPARQLResultsXMLWriter; import org.openrdf.repository.Repository; import org.openrdf.repository.RepositoryConnection; import org.openrdf.repository.RepositoryException; import org.openrdf.repository.sail.SailRepository; import org.openrdf.rio.RDFFormat; import org.openrdf.rio.rdfxml.RDFXMLWriter; import org.openrdf.sail.SailException; import org.openrdf.sail.helpers.SailBase; import org.openrdf.sail.memory.MemoryStore; import org.openrdf.sail.nativerdf.NativeStore; import org.openrdf.sail.rdbms.mysql.MySqlStore; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import de.fuberlin.wiwiss.marbles.dataproviders.DataProvider; import de.fuberlin.wiwiss.marbles.loading.CacheController; import de.fuberlin.wiwiss.marbles.loading.ContentTypes; import de.fuberlin.wiwiss.marbles.loading.SemanticWebClient; import de.fuberlin.wiwiss.marbles.loading.SpongerProvider; import edu.mit.simile.fresnel.configuration.Configuration; import edu.mit.simile.fresnel.configuration.NoResultsException; import edu.mit.simile.fresnel.purpose.Purpose; import edu.mit.simile.fresnel.results.Selection; /** * Implements REST services to view, discover, load and clear URIs/URLs, as well as a SPARQL endpoint * * @author Christian Becker * * @web.servlet * name="MarblesServlet" * display-name="MarblesServlet" * * @web.servlet-mapping * url-pattern="/marbles" * */ public class MarblesServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { static final long serialVersionUID = 1L; /* Parameters read from web.xml */ /** * Path to data directory with subdirectories for fresnel configuration ("fresnel"), * built-in ontologies ("ontologies") and XSLT transformations ("xsl"), absolute or relative to the Marbles app directory */ private String dataRoot; /** * Full HTTP path to assets in the "web" directory */ private URL assetsURL = null; /** * HTTP URL of this service */ private URL serviceURL = null; /** * The directory that contains the fresnel configuration */ private final String fresnelDirectory = "fresnel"; /** * The directory that contains ontologies to load */ private final String ontologiesDirectory = "ontologies"; /** * The directory that contains the XSLT stylesheet */ private final String xslDirectory = "xsl"; /** * The filename of the XSLT stylesheet to use */ private final String xslTransformation = "to-xhtml.xsl"; private Logger logger; private CacheController cacheController; private SemanticWebClient semwebClient; SailRepository confRepository = null, ontoRepository = null, dataRepository = null, metaDataRepository = null; SameAsInferencer sameAsInferencer = null; ValueFactory valueFactory = null; /** * Converts a relative path to an absolute, if necessary * @param directory * @returns absolutized path, or null if invalid */ private String getAbsolutePath(String directory, ServletContext context) { if (directory != null && !new File(directory).isDirectory() && new File(context.getRealPath(directory)).isDirectory()) return context.getRealPath(directory); else return directory; } /** * Reads servlet configuration, initializes Sesame repositories and loads ontologies */ @Override public void init(ServletConfig config) throws ServletException { super.init(config); ServletContext context = config.getServletContext(); dataRoot = getAbsolutePath(config.getInitParameter("dataRoot"), context); if (!(dataRoot != null && new File(dataRoot).isDirectory())) throw new ServletException("Invalid dataRoot " + (dataRoot == null ? "(null)" : dataRoot)); try { if (config.getInitParameter("assetsURL") != null) assetsURL = new URL(config.getInitParameter("assetsURL")); } catch (Exception e) { throw new ServletException("Invalid assetsURL " + config.getInitParameter("assetsURL")); } try { if (config.getInitParameter("serviceURL") != null) serviceURL = new URL(config.getInitParameter("serviceURL")); } catch (Exception e) { throw new ServletException("Invalid serviceURL " + config.getInitParameter("serviceURL")); } org.apache.log4j.BasicConfigurator.configure(); boolean enableDebugging = (config.getInitParameter("enableDebugging") != null && config.getInitParameter("enableDebugging").equalsIgnoreCase("true")); Logger.getRootLogger().setLevel(enableDebugging ? Level.DEBUG : Level.WARN); /* Set up HTTP Client logging */ // Commented out at this should be configured on the server level // System.setProperty("org.apache.commons.logging.Log", "org.apache.commons.logging.impl.Log4JLogger"); // System.setProperty("org.apache.commons.logging.simplelog.showdatetime", "true"); // System.setProperty("org.apache.commons.logging.simplelog.log.httpclient.wire.header", "debug"); // System.setProperty("org.apache.commons.logging.simplelog.log.org.apache.commons.httpclient", "debug"); /* Set up Sesame MySQL RDBMS */ try { confRepository = new SailRepository(new MemoryStore()); confRepository.initialize(); ontoRepository = new SailRepository( new NativeStore(new File(getAbsolutePath(config.getInitParameter("ontologyStore"), context)))); ontoRepository.initialize(); SailBase baseStore = null; if (config.getInitParameter("mysqlDb") != null && config.getInitParameter("mysqlServer") != null && config.getInitParameter("mysqlUser") != null && config.getInitParameter("mysqlPass") != null) { MySqlStore myStore = new MySqlStore(config.getInitParameter("mysqlDb")); myStore.setServerName(config.getInitParameter("mysqlServer")); myStore.setUser(config.getInitParameter("mysqlUser")); myStore.setPassword(config.getInitParameter("mysqlPass")); myStore.setMaxNumberOfTripleTables(16); //myStore.setIndexed(true); baseStore = myStore; } else { baseStore = new NativeStore( new File(getAbsolutePath(config.getInitParameter("cacheStore"), context))); } /* SameAsInferencer requires an InferencerConnection, which is provided by the native store */ sameAsInferencer = new SameAsInferencer(baseStore); sameAsInferencer.setAutoInference(false); dataRepository = new SailRepository(sameAsInferencer); dataRepository.initialize(); metaDataRepository = new SailRepository( new NativeStore(new File(getAbsolutePath(config.getInitParameter("metadataStore"), context)))); metaDataRepository.initialize(); RepositoryConnection ontoConn = ontoRepository.getConnection(); ValueFactory ontoValueFactory = ontoRepository.getValueFactory(); /* Load ontologies */ File ontoDir = new File(dataRoot + "/" + ontologiesDirectory); for (File f : ontoDir.listFiles(new RDFFilenameFilter())) { URI ontoResource = ontoValueFactory.createURI("file://" + f.getName()); /* Only load new ontologies */ if (!ontoConn.hasStatement(null, null, null, false, ontoResource)) { try { loadTriples(ontoRepository, f, null /* parameters */, ontoResource); } catch (Exception e) { System.err.println("Error loading " + f.getName()); e.printStackTrace(); } } } ontoConn.close(); valueFactory = dataRepository.getValueFactory(); /* Set up external data providers */ ArrayList<DataProvider> dataProviders = new ArrayList<DataProvider>(); if (config.getInitParameter("dataProviders") != null) { String[] providers = config.getInitParameter("dataProviders").split(","); for (String dsName : providers) { try { DataProvider d = (DataProvider) (this.getClass().getClassLoader().loadClass(dsName)) .newInstance(); dataProviders.add(d); } catch (ClassNotFoundException e) { e.printStackTrace(); } } } /* Set up Virtuoso Sponger */ SpongerProvider spongerProvider = null; if (config.getInitParameter("spongerServiceURL") != null) { spongerProvider = new SpongerProvider(config.getInitParameter("spongerServiceURL")); } cacheController = new CacheController(dataRepository, metaDataRepository); semwebClient = new SemanticWebClient(cacheController, spongerProvider, dataProviders); } catch (Exception e) { e.printStackTrace(); } } /** * Shuts down repositories */ @Override public void destroy() { try { if (dataRepository != null) dataRepository.shutDown(); if (metaDataRepository != null) metaDataRepository.shutDown(); if (ontoRepository != null) ontoRepository.shutDown(); if (confRepository != null) confRepository.shutDown(); } catch (RepositoryException e) { // TODO Auto-generated catch block e.printStackTrace(); } super.destroy(); } /** * Loads fresnel configuration, substituting the "##lang##" * parameter for a specified language * * @param language Language tag to use, e.g. "en" or "de" * @throws Exception */ private void loadFresnelConfig(String language) throws Exception { RepositoryConnection configConn = confRepository.getConnection(); configConn.remove((Resource) null, null, null); configConn.commit(); configConn.close(); HashMap<String, String> parameters = new HashMap<String, String>(); parameters.put("lang", language); File fresnelDir = new File(dataRoot + "/" + fresnelDirectory); for (File f : fresnelDir.listFiles(new RDFFilenameFilter())) { loadTriples(confRepository, f, parameters); } } /** * Handles HTTP GET and POST requests * * @param request * @param response * @throws IOException */ protected void handleRequest(HttpServletRequest request, HttpServletResponse response) throws IOException { response.setContentType("text/html"); response.setCharacterEncoding("utf-8"); /* Try to prevent spidering */ response.setHeader("X-Robots-Tag", "nofollow"); OutputStream outputStream = response.getOutputStream(); /* Call REST services */ if (request.getParameter("do") != null) { if (request.getParameter("do").equals("clear") && request.getParameter("url") != null) { clearData(request.getParameter("url"), outputStream); } else if (request.getParameter("do").equals("load") && request.getParameter("url") != null) { loadData(request.getParameter("url"), outputStream); } else if (request.getParameter("do").equals("discover") && request.getParameter("uri") != null) { discoverResource(request.getParameter("uri"), outputStream); } } else if (request.getParameter("query") != null) { sparqlQuery(request, response, outputStream); /* recognize SPARQL queries using the <code>query</code> parameter */ } else fresnelView(request, response); /* default to view generation */ } /** * Removes an URL from the cache (<code>clear</code>) * @param url The URL to remove * @param outputStream Output stream to communicate the result to */ private void clearData(String url, OutputStream outputStream) { cacheController.removeData(url); PrintWriter writer = new PrintWriter(outputStream); writer.print("ok"); writer.close(); } /** * (Re-)loads an URL into the cache (<code>load</code>) * @param url The URL to load * @param outputStream Output stream to communicate the result to */ private void loadData(String url, OutputStream outputStream) { try { semwebClient.loadURL(new org.apache.commons.httpclient.URI(url, true), true /* wait */); } catch (URIException e) { e.printStackTrace(); } catch (NullPointerException e) { e.printStackTrace(); } PrintWriter writer = new PrintWriter(outputStream); writer.print("ok"); writer.close(); } /** * Tries to dereference the URI and queries data providers for data; * then follows known predicates (<code>discover</code>) * * @param uri The resource of interest * @param outputStream Output stream to communicate the result to */ public void discoverResource(String uri, OutputStream outputStream) { Resource mainResource = valueFactory.createURI(uri); List<org.apache.commons.httpclient.URI> retrievedURLs = semwebClient.discoverResource(mainResource, false /* don't wait */); try { sameAsInferencer.addInferredForResource(mainResource); } catch (SailException e) { e.printStackTrace(); } catch (RepositoryException e) { e.printStackTrace(); } /* List retrieved URLs for debugging purposes */ PrintWriter writer = new PrintWriter(outputStream); if (retrievedURLs != null) { for (org.apache.commons.httpclient.URI url : retrievedURLs) { writer.println(url.toString() + "<br/>"); } } writer.close(); } /** * Handles a SPARQL query. * The endpoint supports the <code>SELECT</code>, <code>CONSTRUCT</code> and * <code>DESCRIBE</code> query forms; triple serialization is limited to the <code>RDF/XML<code> format. * The indication of graphs using the <code>defaultgraphuri</code> and <code>namedgraphuri</code> * elements is not supported; however graphs may be indicated in the query text using * <code>FROM</code> and <code>FROM NAMED</code> keywords * * @param request * @param response * @param outputStream */ private void sparqlQuery(HttpServletRequest request, HttpServletResponse response, OutputStream outputStream) { RepositoryConnection conn = null; String query = request.getParameter("query"); try { conn = dataRepository.getConnection(); Query q = conn.prepareQuery(QueryLanguage.SPARQL, query); if (q instanceof TupleQuery) { /* <code>SELECT</code> form */ response.setContentType("application/sparql-results+xml"); SPARQLResultsXMLWriter sparqlWriter = new SPARQLResultsXMLWriter(outputStream); ((TupleQuery) q).evaluate(sparqlWriter); } else if (q instanceof GraphQuery) { /* <code>CONSTRUCT</code> and <code>DESCRIBE</code> forms */ response.setContentType("application/rdf+xml"); RDFXMLWriterUnique rdfXmlWriter = new RDFXMLWriterUnique(outputStream); ((GraphQuery) q).evaluate(rdfXmlWriter); } } catch (MalformedQueryException e) { /* Report errors using HTTP 400 Bad Request and provide error details */ //response.setStatus(400); PrintWriter printWriter = new PrintWriter(outputStream); printWriter.write("Unable to parse query: " + e.getMessage()); printWriter.close(); e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } finally { if (conn != null) try { conn.close(); } catch (RepositoryException e) { e.printStackTrace(); } } } /** * Discovers an URI and renders a given view for it (<code>view</code>). * * @param request * @param response * @throws IOException */ public void fresnelView(HttpServletRequest request, HttpServletResponse response) throws IOException { PrintWriter writer = new PrintWriter(new OutputStreamWriter(response.getOutputStream(), "UTF-8")); String errorString = null; Selection selected = null; List<org.apache.commons.httpclient.URI> retrievedURLs = null; Resource focalResource = null; Configuration conf = null; String redirectLocation = null; try { /* Reload the Fresnel configuration using the provided language */ String langPref = (request.getParameter("lang") != null ? request.getParameter("lang") : "en"); loadFresnelConfig(langPref); conf = new Configuration(confRepository, ontoRepository); /* Create the focal resource */ if (request.getParameter("uri") != null) { String uriString = request.getParameter("uri"); if (uriString.startsWith("_:")) /* blank node */ focalResource = valueFactory.createBNode(uriString.substring(2)); else focalResource = valueFactory.createURI(uriString); /* Collect data about the focal resource */ if (request.getParameter("skipload") == null) { retrievedURLs = semwebClient.discoverResource(focalResource, true /* wait */); } /* skip */ /* Initiate manual owl:sameAs inference */ if (request.getParameter("skipInference") == null) { sameAsInferencer.addInferredForResource(focalResource); } if (conf.hasWarnings()) writer.println(conf.getWarningsString()); Purpose purpose = null; /* Look up the requested lens purpose */ if (request.getParameter("purpose") != null && (!request.getParameter("purpose").equals("defaultPurpose"))) purpose = new Purpose(new URIImpl(Constants.nsFresnelExt + request.getParameter("purpose"))); else purpose = new Purpose(new URIImpl( "http://www.w3.org/2004/09/fresnel#defaultLens")); /* this must be provided, or a random lens is chosen */ try { /* Perform Fresnel selection using the requested display purpose and language */ selected = conf.select(dataRepository, focalResource, purpose, langPref); /* Perform Fresnel formatting */ selected = conf.format(dataRepository, selected); } catch (NoResultsException e) { /* * If no results are found, redirect the user to the resource * if it is not an RDF document. * This code is not reached when there already is some data about the resource. */ RepositoryConnection metaDataConn = null; try { metaDataConn = metaDataRepository.getConnection(); /* Manual support for one level of redirects */ String resourceRedirect = cacheController.getCachedHeaderDataValue(metaDataConn, focalResource, "location"); Resource resourceURI = (resourceRedirect == null ? focalResource : new URIImpl(resourceRedirect)); /* Get target content type */ String contentType = cacheController.getCachedHeaderDataValue(metaDataConn, resourceURI, "content-type"); if (contentType != null && !ContentTypes.isRDF(contentType)) { redirectLocation = focalResource.toString(); } } catch (RepositoryException re) { re.printStackTrace(); } catch (IllegalArgumentException ie) { ie.printStackTrace(); } finally { try { if (metaDataConn != null) metaDataConn.close(); } catch (RepositoryException re) { re.printStackTrace(); } } } } /* uri != null */ } catch (Exception e) { e.printStackTrace(); errorString = e.getMessage(); } /* Output */ try { /* Handle redirection to non-RDF data */ if (redirectLocation != null) { response.setHeader("Location", redirectLocation); response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY); } else { /* Perform XSL output */ /* * When there are no results, we still need a selection object in * order to render the fresnel tree */ if (selected == null) selected = new Selection(conf); Document fresnelTree = selected.render(); addSources(fresnelTree, retrievedURLs); /* Prepare XSLT */ StreamSource styleSource = new StreamSource( new File(dataRoot + "/" + xslDirectory + "/" + xslTransformation)); net.sf.saxon.TransformerFactoryImpl tf = new net.sf.saxon.TransformerFactoryImpl(); Transformer styleTransformer = tf.newTransformer(styleSource); /* Debug output */ if (request.getParameter("debug") != null) { /* debug output: fresnel tree */ StringWriter stringWriter = new StringWriter(); Transformer treeTransformer = tf.newTransformer(); treeTransformer.setOutputProperty(OutputKeys.INDENT, "yes"); treeTransformer.transform(new DOMSource(fresnelTree), new StreamResult(stringWriter)); styleTransformer.setParameter("fresnelTree", stringWriter.getBuffer().toString()); } /* Apply parameters */ styleTransformer.setParameter("assetsURL", assetsURL != null ? assetsURL.toString() : ""); styleTransformer.setParameter("serviceURL", serviceURL != null ? serviceURL.toString() : ""); styleTransformer.setParameter("errorString", errorString); styleTransformer.setParameter("mainResource", focalResource != null ? focalResource.toString() : ""); if (request.getParameter("purpose") != null) styleTransformer.setParameter("purpose", request.getParameter("purpose")); else styleTransformer.setParameter("purpose", "defaultPurpose"); if (request.getParameter("mobile") != null) styleTransformer.setParameter("isMobile", request.getParameter("mobile")); HashMap<String, String[]> newParameters = new HashMap<String, String[]>(request.getParameterMap()); if (!newParameters.containsKey("lang")) newParameters.put("lang", new String[] { "en" }); for (Object key : new String[] { "purpose", "uri" }) { newParameters.remove(key); } String parameterString = ""; /* Serialize parameters for use in HTML links and forms */ for (Object key : newParameters.keySet()) { parameterString += (parameterString.equals("") ? "" : "&") + key + "=" + ((String[]) newParameters.get(key))[0]; } styleTransformer.setParameter("sessionParams", parameterString); /* Perform rendering */ StreamResult res = new StreamResult(writer); styleTransformer.setOutputProperty(OutputKeys.INDENT, "yes"); styleTransformer.transform(new DOMSource(fresnelTree), res); } } catch (Exception e) { e.printStackTrace(); writer.print(e.getMessage()); } finally { } } /* (non-Java-doc) * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException { handleRequest(request, response); } /* (non-Java-doc) * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { handleRequest(request, response); } /** * Reads data from a URL in a given syntax into a Sesame repository; * supports {@link ParamReader} * * @param store Add RDF to this <code>LocalRepository</code> * @param url The <code>String</code> location of the data * @param syntax The <code>String</code> syntax of the data * @throws Exception For any problems encountered during read of data from the URL */ public static void loadTriples(Repository store, File file, HashMap<String, String> parameters, Resource... context) throws Exception { RDFFormat format = null; if (file.getName().endsWith(".nt")) format = RDFFormat.NTRIPLES; else if (file.getName().endsWith(".rdf")) format = RDFFormat.RDFXML; else if (file.getName().endsWith(".n3")) format = RDFFormat.N3; else if (file.getName().endsWith(".ttl")) format = RDFFormat.TURTLE; else throw new ServletException("No RDF format known for " + file.getName()); String baseURI = "file://" + file.getAbsoluteFile(); RepositoryConnection conn = store.getConnection(); BufferedReader fileReader = new BufferedReader(new FileReader(file)); if (parameters != null) { ParamReader paramReader = new ParamReader(parameters, fileReader); conn.add(paramReader, baseURI, format, context); } else conn.add(fileReader, baseURI, format, context); conn.commit(); conn.close(); } /** * Filename filter that accepts only file extensions commonly used for RDF data, namely * <code>.nt</code>, <code>.rdf</code>, <code>.ttl</code>, <code>.n3</code> */ private class RDFFilenameFilter implements FilenameFilter { public boolean accept(File dir, String name) { return (!name.startsWith(".")) && (name.endsWith(".nt") || name.endsWith(".rdf") || name.endsWith(".ttl") || name.endsWith(".n3")); } } /** * Enhances source data with consistently colored icons; * adds detailed source list to Fresnel output * * @param doc The Fresnel tree */ private void addSources(Document doc, List<org.apache.commons.httpclient.URI> retrievedURLs) { int colorIndex = 0; HashMap<String, Source> sources = new HashMap<String, Source>(); NodeList nodeList = doc.getElementsByTagName("source"); int numNodes = nodeList.getLength(); for (int i = 0; i < numNodes; i++) { Node node = nodeList.item(i); String uri = node.getFirstChild().getFirstChild().getNodeValue(); Source source; /* Get source, create it if necessary */ if (null == (source = sources.get(uri))) { source = new Source(uri); colorIndex = source.determineIcon(colorIndex); sources.put(uri, source); } /* Enhance source reference with icon */ Element sourceIcon = doc.createElementNS(Constants.nsFresnelView, "sourceIcon"); sourceIcon.appendChild(doc.createTextNode(source.getIcon())); node.appendChild(sourceIcon); } /* Supplement source list with retrieved URLs */ if (retrievedURLs != null) for (org.apache.commons.httpclient.URI uri : retrievedURLs) { Source source; if (null == (source = sources.get(uri.toString()))) { source = new Source(uri.toString()); colorIndex = source.determineIcon(colorIndex); sources.put(uri.toString(), source); } } /* Provide list of sources */ RepositoryConnection metaDataConn = null; try { metaDataConn = metaDataRepository.getConnection(); Element sourcesElement = doc.createElementNS(Constants.nsFresnelView, "sources"); for (String uri : sources.keySet()) { Source source = sources.get(uri); sourcesElement.appendChild(source.toElement(doc, cacheController, metaDataConn)); } Node results = doc.getFirstChild(); results.appendChild(sourcesElement); } catch (RepositoryException e) { e.printStackTrace(); } finally { try { if (metaDataConn != null) metaDataConn.close(); } catch (RepositoryException e) { e.printStackTrace(); } } } }