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.middleware; import de.tu_dortmund.ub.hb_ng.middleware.preprocessing.PreprocessingInterface; import de.tu_dortmund.ub.util.impl.Lookup; 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.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.log4j.Logger; import org.apache.log4j.PropertyConfigurator; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.*; import java.net.SocketTimeoutException; import java.util.Enumeration; import java.util.Properties; import java.util.stream.Collectors; /** * Middleware HB-NG Endpoint * * @author Dipl.-Math. Hans-Georg Becker, M.L.I.S. (UB Dortmund) * @version 2015-08-21 * */ public class MiddlewareHbNgEndpoint extends HttpServlet { public static final String UTF_8 = "UTF-8"; private static Properties config = new Properties(); private static Logger logger = Logger.getLogger(MiddlewareHbNgEndpoint.class.getName()); public MiddlewareHbNgEndpoint(String conffile) { // Init properties try { try (InputStream inputStream = new FileInputStream(conffile)) { try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, UTF_8))) { this.config.load(reader); } } } catch (IOException e) { this.logger.error("something went wrong", e); this.logger.error(String.format("FATAL ERROR: Could not read '%s'!", conffile)); } // init logger PropertyConfigurator.configure(this.config.getProperty(HBNGStatics.SERVICE_LOG4J_CONF_IDENTIFIER)); final String serviceName = this.config.getProperty(HBNGStatics.SERVICE_NAME_IDENTIFIER); logger.info( String.format("[%s] Starting '" + MiddlewareHbNgEndpoint.class.getName() + "' ...", serviceName)); logger.info(String.format("[%s] conf-file = %s", serviceName, conffile)); final String log4jConfFile = this.config.getProperty(HBNGStatics.SERVICE_LOG4J_CONF_IDENTIFIER); logger.info(String.format("[%s] log4j-conf-file = %s", serviceName, log4jConfFile)); } public void doOptions(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setHeader("Access-Control-Allow-Methods", this.config.getProperty(HBNGStatics.CORS_ACCESS_CONTROL_ALLOW_METHODS_IDENTIFIER)); response.addHeader("Access-Control-Allow-Headers", this.config.getProperty(HBNGStatics.CORS_ACCESS_CONTROL_ALLOW_HEADERS_IDENTIFIER)); response.setHeader("Access-Control-Allow-Origin", this.config.getProperty(HBNGStatics.CORS_ACCESS_CONTROL_ALLOW_ORIGIN_IDENTIFIER)); response.setHeader("Accept", this.config.getProperty(HBNGStatics.CORS_ACCEPT_IDENTIFIER)); response.getWriter().println(); } protected void doPost(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException { // CORS ORIGIN RESPONSE HEADER httpServletResponse.setHeader("Access-Control-Allow-Origin", config.getProperty(HBNGStatics.CORS_ACCESS_CONTROL_ALLOW_ORIGIN_IDENTIFIER)); String authorization = ""; String contenttype = ""; Enumeration<String> headerNames = httpServletRequest.getHeaderNames(); while (headerNames.hasMoreElements()) { String headerNameKey = headerNames.nextElement(); this.logger.debug("headerNameKey = " + headerNameKey + " / headerNameValue = " + httpServletRequest.getHeader(headerNameKey)); if (headerNameKey.equals("Authorization")) { authorization = httpServletRequest.getHeader(headerNameKey); } if (headerNameKey.equals("Content-Type")) { contenttype = httpServletRequest.getHeader(headerNameKey); } } this.logger.info("contenttype = " + contenttype); try { // TODO validate Content-Type String data = httpServletRequest.getReader().lines() .collect(Collectors.joining(System.lineSeparator())); if (data == null || data.equals("")) { this.logger.error(HttpServletResponse.SC_NO_CONTENT + " - No Content"); httpServletResponse.sendError(HttpServletResponse.SC_NO_CONTENT, "No Content"); } else { String postableData = null; // TODO bind interface Preprocessing if (Lookup.lookupAll(PreprocessingInterface.class).size() > 0) { PreprocessingInterface preprocessingInterface = Lookup.lookup(PreprocessingInterface.class); // init Authorization Service preprocessingInterface.init(this.config); postableData = preprocessingInterface.process(data); } else { // TODO correct error handling this.logger.error("[" + this.config.getProperty("service.name") + "] " + HttpServletResponse.SC_INTERNAL_SERVER_ERROR + ": " + "Authorization Interface not implemented!"); } if (postableData != null) { // TODO if successful then POST as application/sparql-update to LinkedDataPlatform String sparql_url = this.config.getProperty("ldp.sparql-endpoint"); // HTTP Request int timeout = Integer.parseInt(this.config.getProperty("ldp.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.addHeader("Authorization", this.config.getProperty("ldp.authorization")); httpPost.setEntity(new StringEntity(postableData)); 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() + "] LDP request - " + (elapsed / 1000.0 / 1000.0 / 1000.0) + " s"); try { int statusCode = httpResponse.getStatusLine().getStatusCode(); HttpEntity httpEntity = httpResponse.getEntity(); // TODO httpServletResponse.setStatus(statusCode); httpServletResponse.getWriter().println(httpResponse.getStatusLine().getReasonPhrase()); EntityUtils.consume(httpEntity); } finally { httpResponse.close(); } } finally { httpclient.close(); } } } } catch (Exception e) { this.logger.error("something went wrong", e); httpServletResponse.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, "something went wrong"); } } }