Java tutorial
/* The MIT License (MIT) Copyright (c) 2015, Hans-Georg Becker, http://orcid.org/0000-0003-0432-294X Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ package de.tu_dortmund.ub.hb_ng; import de.tu_dortmund.ub.data.ldp.storage.LinkedDataStorage; import de.tu_dortmund.ub.data.ldp.storage.LinkedDataStorageException; import net.sf.saxon.s9api.*; import org.apache.commons.io.IOUtils; import org.apache.http.HttpEntity; import org.apache.http.client.config.RequestConfig; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.conn.ConnectTimeoutException; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; import org.apache.jena.graph.Triple; import org.apache.jena.query.Query; import org.apache.jena.query.QueryFactory; import org.apache.log4j.Logger; import org.apache.log4j.PropertyConfigurator; import org.jdom2.Document; import org.jdom2.JDOMException; import org.jdom2.input.SAXBuilder; import org.jdom2.output.XMLOutputter; import org.jdom2.transform.JDOMSource; import org.openrdf.model.Statement; import org.openrdf.model.URI; import org.openrdf.model.Value; import org.openrdf.model.ValueFactory; import org.openrdf.model.impl.ValueFactoryImpl; import org.openrdf.query.BindingSet; import org.openrdf.query.TupleQueryResult; import org.openrdf.query.impl.TupleQueryResultBuilder; import org.openrdf.query.resultio.sparqlxml.SPARQLResultsXMLParser; import org.openrdf.rio.RDFFormat; import org.openrdf.rio.RDFParser; import org.openrdf.rio.RDFWriter; import org.openrdf.rio.Rio; import org.openrdf.rio.helpers.StatementCollector; import javax.json.Json; import javax.json.JsonArray; import javax.json.JsonObject; import javax.json.JsonReader; import javax.xml.transform.stream.StreamSource; import java.io.*; import java.net.SocketTimeoutException; import java.net.URL; import java.net.URLDecoder; import java.net.URLEncoder; import java.util.*; /** * Implementation of the LinkedDataStorage interface for hb_ng's de.tu_dortmund.ub.hb_ng.data.SolRDF * * @author Dipl.-Math. Hans-Georg Becker, M.L.I.S. (UB Dortmund) * @version 2015-08-15 */ public class SolRDF implements LinkedDataStorage { private Properties config = null; private Logger logger = null; @Override public void init(Properties config) { this.config = config; PropertyConfigurator.configure(this.config.getProperty("service.log4j-conf")); this.logger = Logger.getLogger(SolRDF.class.getName()); } @Override public HashMap<String, String> health(Properties properties) { this.logger.info("[" + config.getProperty("service.name") + "] " + "health requested"); HashMap<String, String> health = new HashMap<String, String>(); // Teste Verbindung zu SolRDF try { this.logger.info("[" + config.getProperty("service.name") + "] " + "SolRDF try to start session"); new SAXBuilder().build(new URL(this.config.getProperty("storage.search-endpoint") + "&wt=xml")); this.logger.info("[" + config.getProperty("service.name") + "] " + "SolRDF ok"); health.put("SolRDF", "ok"); } catch (Exception e) { e.printStackTrace(); this.logger.info("[" + config.getProperty("service.name") + "] " + "SolRDF failed"); health.put("SolRDF", "failed"); } return health; } @Override public String getResource(String uri, String format) throws LinkedDataStorageException { return this.getResource(null, uri, format, false); } @Override public String getResource(String uri, String format, boolean isAuthorized) throws LinkedDataStorageException { return this.getResource(null, uri, format, false); } @Override public String getResource(String graph, String uri, String format) throws LinkedDataStorageException { return this.getResource(graph, uri, format, false); } @Override public String getResource(String graph, String uri, String format, boolean isAuthorized) throws LinkedDataStorageException { this.logger.info("getResource: " + graph); this.logger.info("getResource: " + uri); this.logger.info("getResource: " + format); this.logger.info("getResource: " + isAuthorized); String resource = null; String queryResult = this.doResourceRequest(graph, uri, format, isAuthorized); if (queryResult != null && !queryResult.equals("")) { try { switch (format) { case "html": { Document document = new SAXBuilder().build(new StringReader(queryResult)); StringWriter stringWriter = new StringWriter(); stringWriter.write(htmlOutputter(document, this.config.getProperty("xslt.resource"), null)); resource = stringWriter.toString(); break; } case "rdf.xml": { Document document = new SAXBuilder().build(new StringReader(queryResult)); StringWriter stringWriter = new StringWriter(); XMLOutputter xmlOutputter = new XMLOutputter(); xmlOutputter.output(document, stringWriter); resource = stringWriter.toString(); break; } case "rdf.ttl": { resource = queryResult; break; } case "json": { resource = queryResult; break; } case "nquads": { resource = queryResult; break; } } } catch (JDOMException | IOException e) { throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } } return resource; } @Override public String getAccessRights(String resource) throws LinkedDataStorageException { return this.getAccessRights(null, resource); } @Override public String getAccessRights(String graph, String uri) throws LinkedDataStorageException { this.logger.info("getAccessRights: graph=" + graph); this.logger.info("getAccessRights: uri=" + uri); String accessRights = ""; if (uri.endsWith("/about")) { accessRights = "public"; } else { // TODO config.properties String sparql = "SELECT ?o WHERE { GRAPH <http://data.ub.tu-dortmund.de/graph/" + this.config.getProperty("storage.graph.main") + "-public> { <" + uri + "/about> <http://purl.org/dc/terms#accessRights> ?o } }"; try { JsonReader jsonReader = Json.createReader( IOUtils.toInputStream(this.sparqlQuery(graph, URLEncoder.encode(sparql, "UTF-8"), "application/sparql-results+json;charset=UTF-8"), "UTF-8")); JsonObject jsonObject = jsonReader.readObject(); JsonArray bindings = jsonObject.getJsonObject("results").getJsonArray("bindings"); if (bindings.size() == 0) { accessRights = "internal"; } else { for (JsonObject binding : bindings.getValuesAs(JsonObject.class)) { accessRights = binding.getJsonObject("o").getJsonString("value").getString(); } } this.logger.info("accessRights: " + accessRights); } catch (IOException e) { this.logger.error("something went wrong", e); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } } return accessRights; } @Override public String searchResource(Properties query, String format) throws LinkedDataStorageException { return this.searchResource(null, query, format, false); } @Override public String searchResource(Properties query, String format, boolean isAuthorized) throws LinkedDataStorageException { return this.searchResource(null, query, format, false); } @Override public String searchResource(String graph, Properties query, String format) throws LinkedDataStorageException { return this.searchResource(graph, query, format, false); } @Override public String searchResource(String graph, Properties query, String format, boolean isAuthorized) throws LinkedDataStorageException { // TODO implement search return null; } @Override public String sparqlQuery(String query, String format) throws LinkedDataStorageException { return this.sparqlQuery(null, query, format, false); } @Override public String sparqlQuery(String query, String format, boolean isAuthorized) throws LinkedDataStorageException { return this.sparqlQuery(null, query, format, false); } @Override public String sparqlQuery(String graph, String query, String format) throws LinkedDataStorageException { return this.sparqlQuery(graph, query, format, false); } @Override public String sparqlQuery(String graph, String queryString, String format, boolean isAuthorized) throws LinkedDataStorageException { String resource = null; try { this.logger.info("sparqlQuery: graph=" + graph); this.logger.info("sparqlQuery: queryString=" + queryString); this.logger.info("sparqlQuery: queryString=" + URLDecoder.decode(queryString, "UTF-8")); this.logger.info("sparqlQuery: format=" + format); this.logger.info("sparqlQuery: isAuthorized=" + isAuthorized); if (format.contains("json")) { format = "application/sparql-results+json"; } else { format = "application/sparql-results+xml"; } // HttpRequest zu de.tu_dortmund.ub.hb_ng.data.SolRDF - queryString resource = this.postQueryDirectly(URLDecoder.decode(queryString, "UTF-8"), format); this.logger.info(resource); } catch (Exception e) { this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting Linked Media Framework " + " - " + e.getMessage()); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } return resource; } @Override public String sparqlUpdate(String data) throws LinkedDataStorageException { String code = ""; // de.tu_dortmund.ub.hb_ng.data.SolRDF String sparql_url = this.config.getProperty("storage.sparql-endpoint"); // HTTP Request int timeout = Integer.parseInt(this.config.getProperty("storage.timeout")); RequestConfig defaultRequestConfig = RequestConfig.custom().setSocketTimeout(timeout) .setConnectTimeout(timeout).setConnectionRequestTimeout(timeout).build(); CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(defaultRequestConfig).build(); try { HttpPost httpPost = new HttpPost(sparql_url); httpPost.addHeader("Content-Type", "application/sparql-update"); httpPost.setEntity(new StringEntity(data)); CloseableHttpResponse httpResponse = null; long start = System.nanoTime(); try { httpResponse = httpclient.execute(httpPost); } catch (ConnectTimeoutException | SocketTimeoutException e) { this.logger.info( "[" + this.getClass().getName() + "] " + e.getClass().getName() + ": " + e.getMessage()); httpResponse = httpclient.execute(httpPost); } long elapsed = System.nanoTime() - start; this.logger.info("[" + this.getClass().getName() + "] de.tu_dortmund.ub.hb_ng.data.SolRDF request - " + (elapsed / 1000.0 / 1000.0 / 1000.0) + " s"); try { int statusCode = httpResponse.getStatusLine().getStatusCode(); HttpEntity httpEntity = httpResponse.getEntity(); switch (statusCode) { case 200: { code = "201"; this.logger.info("[" + this.getClass().getName() + "] " + new Date() + " - Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); break; } case 201: { code = "201"; this.logger.info("[" + this.getClass().getName() + "] " + new Date() + " - Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); break; } default: { code = String.valueOf(statusCode); this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); } } EntityUtils.consume(httpEntity); } finally { httpResponse.close(); } } catch (Exception e) { this.logger.error("something went wrong ", e); this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " - timeout"); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } finally { try { httpclient.close(); } catch (IOException e) { this.logger.error("something went wrong", e); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } } return code; } private String doResourceRequest(String graph, String uri, String format, boolean isAuthorized) throws LinkedDataStorageException { this.logger.info("doResourceRequest: graph=" + graph); this.logger.info("doResourceRequest: uri=" + uri); this.logger.info("doResourceRequest: format=" + format); this.logger.info("doResourceRequest: isAuthorized=" + isAuthorized); if (graph == null || graph.equals("")) { graph = this.config.getProperty("storage.graph.default"); } this.logger.info("doResourceRequest: graph=" + graph); String result = null; try { // query resource in de.tu_dortmund.ub.hb_ng.data.SolRDF String selectQuery = "SELECT ?p ?o ?c WHERE { GRAPH ?c { <" + uri + "> ?p ?o } }"; // TODO config String resultString = this.sparqlQuery(null, URLEncoder.encode(selectQuery, "UTF-8"), "xml", isAuthorized); // postprocessing SPARQLResultsXMLParser xmlRes = new SPARQLResultsXMLParser(); TupleQueryResultBuilder build = new TupleQueryResultBuilder(); xmlRes.setTupleQueryResultHandler(build); ByteArrayInputStream is = new ByteArrayInputStream(resultString.getBytes("UTF-8")); xmlRes.parse(is); TupleQueryResult tupleRes = build.getQueryResult(); List<String> bindingNames = tupleRes.getBindingNames(); ArrayList<Statement> statements = new ArrayList<Statement>(); ValueFactory valueFactory = ValueFactoryImpl.getInstance(); while (tupleRes.hasNext()) { BindingSet bindingSet = tupleRes.next(); String predicate = bindingSet.getValue(bindingNames.get(0)).stringValue(); String object = bindingSet.getValue(bindingNames.get(1)).stringValue(); String context = bindingSet.getValue(bindingNames.get(2)).stringValue(); // isAuthorized > public + nonpublic if (isAuthorized && context.contains(this.config.getProperty("storage.graph.main")) || context.contains(graph)) { try { statements.add(valueFactory.createStatement(valueFactory.createURI(uri), valueFactory.createURI(predicate), valueFactory.createURI(object), valueFactory.createURI(context))); } catch (IllegalArgumentException e) { statements.add(valueFactory.createStatement(valueFactory.createURI(uri), valueFactory.createURI(predicate), valueFactory.createLiteral(object), valueFactory.createURI(context))); } } // !isAuthorized > public if (!isAuthorized && context.endsWith(this.config.getProperty("storage.graph.main") + "-public") || context.endsWith(graph + "-public")) { try { statements.add(valueFactory.createStatement(valueFactory.createURI(uri), valueFactory.createURI(predicate), valueFactory.createURI(object), valueFactory.createURI(context))); } catch (IllegalArgumentException e) { statements.add(valueFactory.createStatement(valueFactory.createURI(uri), valueFactory.createURI(predicate), valueFactory.createLiteral(object), valueFactory.createURI(context))); } } } if (statements.size() == 0) { result = null; } else { RDFFormat formatString; switch (format) { case "html": { formatString = RDFFormat.RDFXML; break; } case "rdf.xml": { formatString = RDFFormat.RDFXML; break; } case "rdf.ttl": { formatString = RDFFormat.TURTLE; break; } case "json": { formatString = RDFFormat.JSONLD; break; } case "nquads": { formatString = RDFFormat.NQUADS; break; } default: { formatString = RDFFormat.NQUADS; } } StringWriter stringWriter = new StringWriter(); RDFWriter writer = Rio.createWriter(formatString, stringWriter); writer.startRDF(); for (Statement statement : statements) { writer.handleStatement(statement); } writer.endRDF(); result = stringWriter.toString(); } } catch (Exception e) { e.printStackTrace(); this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting Linked Media Framework: " + uri + " - " + e.getMessage()); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } return result; } // TODO private String doSearchRequest(Properties query, String format) throws LinkedDataStorageException { String result = null; int timeout = Integer.parseInt(this.config.getProperty("storage.lmf.timeout")); try { String solr_url = this.config.getProperty("storage.lmf.endpoint.search") + "q=" + URLEncoder.encode(query.getProperty("q"), "UTF-8"); if (query.containsKey("start")) { solr_url += "&start=" + query.getProperty("start"); } if (query.containsKey("fq")) { for (String f : query.getProperty("fq").split(";")) { if (!f.contains(":")) { solr_url += "&fq=" + URLEncoder.encode(f, "UTF-8"); } else { String[] facet = f.split(":"); solr_url += "&fq=" + facet[0] + ":\"" + URLEncoder.encode(f.replace(facet[0] + ":", "").replaceAll("\"", ""), "UTF-8") + "\""; } } } if (query.containsKey("rows")) { solr_url += "&rows=" + query.getProperty("rows"); } if (query.containsKey("sort")) { solr_url += "&sort=" + query.getProperty("sort"); } switch (format) { case "html": { solr_url += "&wt=xml&indent=true"; break; } case "xml": { solr_url += "&wt=xml&indent=true"; break; } case "json": { solr_url += "&wt=json&indent=true"; break; } } String solr_params = "&facet=true&facet.field=lmf.type&facet.missing=true&facet.mincount=1"; solr_url += solr_params; this.logger.info("Solr-URL: " + solr_url); RequestConfig defaultRequestConfig = RequestConfig.custom().setSocketTimeout(timeout) .setConnectTimeout(timeout).setConnectionRequestTimeout(timeout).build(); CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(defaultRequestConfig) .build(); try { HttpGet httpGet = new HttpGet(solr_url); CloseableHttpResponse httpResponse = null; long start = System.nanoTime(); try { httpResponse = httpclient.execute(httpGet); } catch (ConnectTimeoutException | SocketTimeoutException e) { this.logger.info("[" + this.getClass().getName() + "] " + e.getClass().getName() + ": " + e.getMessage()); httpResponse = httpclient.execute(httpGet); } long elapsed = System.nanoTime() - start; this.logger.info("[" + this.getClass().getName() + "] lmf request - " + (elapsed / 1000.0 / 1000.0 / 1000.0) + " s"); try { int statusCode = httpResponse.getStatusLine().getStatusCode(); HttpEntity httpEntity = httpResponse.getEntity(); switch (statusCode) { case 200: { StringWriter writer = new StringWriter(); IOUtils.copy(httpEntity.getContent(), writer, "UTF-8"); result = writer.toString(); break; } default: { this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting Linked Media Framework: " + solr_url + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); throw new LinkedDataStorageException( statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); } } EntityUtils.consume(httpEntity); } finally { httpResponse.close(); } } catch (ConnectTimeoutException | SocketTimeoutException e) { this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting Linked Media Framework: " + solr_url + " - timeout"); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } finally { httpclient.close(); } } catch (Exception e) { this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting Linked Media Framework " + " - " + e.getMessage()); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } return result; } // TODO unntig? private String extendSparqlQueryWithGraph(String queryString, ArrayList<String> graphs) { Query query = QueryFactory.create(queryString); String extendedQuery = ""; if (query.isSelectType()) { extendedQuery += "SELECT "; if (query.isQueryResultStar()) { extendedQuery += "* "; } else { for (String var : query.getResultVars()) { extendedQuery += "?" + var + " "; } } extendedQuery += " WHERE { "; for (int i = 0; i < graphs.size(); i++) { String queryPattern = "{ GRAPH <" + graphs.get(i) + "> " + query.getQueryPattern() + " } "; extendedQuery += queryPattern; if (i < graphs.size() - 1) { extendedQuery += " UNION "; } } extendedQuery += " } "; } else if (query.isDescribeType()) { // TODO DESCRIBE } else if (query.isAskType()) { // TODO ASK } else if (query.isConstructType()) { Map<String, String> prefixMapping = query.getPrologue().getPrefixMapping().getNsPrefixMap(); for (String prefix : prefixMapping.keySet()) { extendedQuery += "PREFIX " + prefix + ": <" + prefixMapping.get(prefix) + "> "; } extendedQuery += "CONSTRUCT { "; for (Triple triple : query.getConstructTemplate().getTriples()) { extendedQuery += triple.getSubject().isVariable() ? "?" + triple.getSubject().getName() + " " : "<" + triple.getSubject() + "> "; extendedQuery += triple.getPredicate().isVariable() ? "?" + triple.getPredicate().getName() + " " : "<" + triple.getPredicate() + "> "; extendedQuery += triple.getObject().isVariable() ? "?" + triple.getObject().getName() + " " : "<" + triple.getObject() + "> "; extendedQuery += ". "; } extendedQuery += "} WHERE { "; for (int i = 0; i < graphs.size(); i++) { String queryPattern = "{ GRAPH <" + graphs.get(i) + "> " + query.getQueryPattern() + " } "; extendedQuery += queryPattern; if (i < graphs.size() - 1) { extendedQuery += " UNION "; } } extendedQuery += " }"; } else { // TODO throw Exception! } return extendedQuery; } private String postQueryDirectly(String query, String format) throws LinkedDataStorageException { String result = null; String sparql_url = this.config.getProperty("storage.sparql-endpoint"); // HTTP Request int timeout = Integer.parseInt(this.config.getProperty("storage.timeout")); RequestConfig defaultRequestConfig = RequestConfig.custom().setSocketTimeout(timeout) .setConnectTimeout(timeout).setConnectionRequestTimeout(timeout).build(); CloseableHttpClient httpclient = HttpClients.custom().setDefaultRequestConfig(defaultRequestConfig).build(); try { HttpPost httpPost = new HttpPost(sparql_url); httpPost.addHeader("Content-Type", "application/sparql-query"); httpPost.addHeader("Accept", format); httpPost.setEntity(new StringEntity(query)); CloseableHttpResponse httpResponse = null; long start = System.nanoTime(); try { httpResponse = httpclient.execute(httpPost); } catch (ConnectTimeoutException | SocketTimeoutException e) { this.logger.info( "[" + this.getClass().getName() + "] " + e.getClass().getName() + ": " + e.getMessage()); httpResponse = httpclient.execute(httpPost); } long elapsed = System.nanoTime() - start; this.logger.info("[" + this.getClass().getName() + "] de.tu_dortmund.ub.hb_ng.data.SolRDF request - " + (elapsed / 1000.0 / 1000.0 / 1000.0) + " s"); try { int statusCode = httpResponse.getStatusLine().getStatusCode(); HttpEntity httpEntity = httpResponse.getEntity(); switch (statusCode) { case 200: { this.logger.info("[" + this.getClass().getName() + "] " + new Date() + " - Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " / " + query + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); StringWriter writer = new StringWriter(); IOUtils.copy(httpEntity.getContent(), writer, "UTF-8"); result = writer.toString(); break; } default: { this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " / " + query + " - " + statusCode + " : " + httpResponse.getStatusLine().getReasonPhrase()); } } EntityUtils.consume(httpEntity); } finally { httpResponse.close(); } } catch (Exception e) { this.logger.error("something went wrong", e); this.logger.error("[" + this.getClass().getName() + "] " + new Date() + " - ERROR: Requesting de.tu_dortmund.ub.hb_ng.data.SolRDF: " + sparql_url + " - timeout"); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } finally { try { httpclient.close(); } catch (IOException e) { this.logger.error("something went wrong", e); throw new LinkedDataStorageException(e.getMessage(), e.getCause()); } } return result; } private String htmlOutputter(Document doc, String xslt, HashMap<String, String> params) throws IOException { String result = null; try { Processor processor = new Processor(false); XsltCompiler xsltCompiler = processor.newXsltCompiler(); XsltExecutable xsltExecutable = xsltCompiler.compile(new StreamSource(xslt)); XdmNode source = processor.newDocumentBuilder().build(new JDOMSource(doc)); Serializer out = new Serializer(); out.setOutputProperty(Serializer.Property.METHOD, "html"); out.setOutputProperty(Serializer.Property.INDENT, "yes"); StringWriter buffer = new StringWriter(); out.setOutputWriter(new PrintWriter(buffer)); XsltTransformer trans = xsltExecutable.load(); trans.setInitialContextNode(source); trans.setDestination(out); if (params != null) { for (String p : params.keySet()) { trans.setParameter(new QName(p), new XdmAtomicValue(params.get(p))); } } trans.transform(); result = buffer.toString(); } catch (SaxonApiException e) { this.logger.error("SaxonApiException: " + e.getMessage()); } return result; } }