it.cloudicaro.disit.servlet.kb.SparqlProxy.java Source code

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Here is the source code for it.cloudicaro.disit.servlet.kb.SparqlProxy.java

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/* Icaro Cloud Knowledge Base (ICKB).
   Copyright (C) 2015 DISIT Lab http://www.disit.org - University of Florence
    
   This program 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 2
   of the License, or (at your option) any later version.
   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 General Public License for more details.
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. */

package it.cloudicaro.disit.servlet.kb;

import it.cloudicaro.disit.kb.Configuration;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.Date;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.impl.client.HttpClients;

/**
    
 */
public class SparqlProxy extends HttpServlet {

    private Log log = LogFactory.getLog(SparqlProxy.class);

    @Override
    public void doGet(HttpServletRequest theReq, HttpServletResponse theResp) throws ServletException, IOException {
        String aSparqlEndpointQuery = theReq.getParameter("query");

        if (log.isDebugEnabled()) {
            log.debug(aSparqlEndpointQuery);
        }

        try {
            buildSparqlResponse(theReq, theResp);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void buildSparqlResponse(HttpServletRequest theReq, HttpServletResponse theResp) throws Exception {
        Date start = new Date();
        HttpClient httpclient = HttpClients.createDefault();
        HttpGet httpget = null;
        HttpResponse response = null;

        String theServerHost = Configuration.getInstance().get("kb.rdf.sparql_endpoint",
                "http://192.168.0.106:8080/openrdf-sesame/repositories/icaro5");
        String query = theReq.getParameter("query");
        String aEncodedQuery = URLEncoder.encode(query, "UTF-8");

        String theReqUrl = theServerHost + "?query=" + aEncodedQuery;
        //System.out.println("request: " + theReqUrl);

        try {
            httpget = new HttpGet(theReqUrl);

            //System.out.println("request header:");
            Enumeration<String> aHeadersEnum = theReq.getHeaderNames();
            while (aHeadersEnum.hasMoreElements()) {
                String aHeaderName = aHeadersEnum.nextElement();
                String aHeaderVal = theReq.getHeader(aHeaderName);
                httpget.setHeader(aHeaderName, aHeaderVal);
                //System.out.println("  "+aHeaderName+": "+aHeaderVal);
            }

            if (log.isDebugEnabled()) {
                log.debug("executing request " + httpget.getURI());
            }

            // Create a response handler
            response = httpclient.execute(httpget);

            //System.out.println("response header:");
            // set the same Headers
            for (Header aHeader : response.getAllHeaders()) {
                if (!aHeader.getName().equals("Transfer-Encoding") || !aHeader.getValue().equals("chunked"))
                    theResp.setHeader(aHeader.getName(), aHeader.getValue());
                //System.out.println("  "+aHeader.getName()+": "+aHeader.getValue());
            }

            // set the same locale
            if (response.getLocale() != null)
                theResp.setLocale(response.getLocale());

            // set the content
            theResp.setContentLength((int) response.getEntity().getContentLength());
            theResp.setContentType(response.getEntity().getContentType().getValue());

            // set the same status
            theResp.setStatus(response.getStatusLine().getStatusCode());

            // redirect the output
            InputStream aInStream = null;
            OutputStream aOutStream = null;
            try {
                aInStream = response.getEntity().getContent();
                aOutStream = theResp.getOutputStream();

                byte[] buffer = new byte[1024];
                int r = 0;
                do {
                    r = aInStream.read(buffer);
                    if (r != -1)
                        aOutStream.write(buffer, 0, r);
                } while (r != -1);
                /*
                        int data = aInStream.read();
                        while (data != -1) {
                          aOutStream.write(data);
                    
                          data = aInStream.read();
                        }
                 */
            } catch (IOException ioe) {
                ioe.printStackTrace();
            } finally {
                if (aInStream != null) {
                    aInStream.close();
                }
                if (aOutStream != null) {
                    aOutStream.close();
                }
            }
            Date end = new Date();
            System.out.println(start + " SPARQL-PERFORMANCE: " + (end.getTime() - start.getTime()) + "ms " + query);
        } finally {
            httpclient.getConnectionManager().closeExpiredConnections();
            httpclient.getConnectionManager().shutdown();
        }
    }
}