Metacat

/**

 *  '$RCSfile$'

 *  Copyright: 2000-2011 Regents of the University of California and the

 *              National Center for Ecological Analysis and Synthesis

 *

 *   '$Author: leinfelder $'

 *     '$Date: 2012-11-29 16:52:29 -0800 (Thu, 29 Nov 2012) $'

 *

 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.index;

import java.io.ByteArrayInputStream;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.StringWriter;

import java.io.Writer;

import javax.xml.parsers.ParserConfigurationException;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.apache.solr.client.solrj.SolrServer;

import org.apache.solr.client.solrj.SolrServerException;

import org.apache.solr.client.solrj.embedded.EmbeddedSolrServer;

import org.apache.solr.client.solrj.response.QueryResponse;

import org.apache.solr.common.params.SolrParams;

import org.apache.solr.core.CoreContainer;

import org.apache.solr.core.SolrCore;

import org.apache.solr.request.LocalSolrQueryRequest;

import org.apache.solr.response.CSVResponseWriter;

import org.apache.solr.response.JSONResponseWriter;

import org.apache.solr.response.PHPResponseWriter;

import org.apache.solr.response.PHPSerializedResponseWriter;

import org.apache.solr.response.PythonResponseWriter;

import org.apache.solr.response.QueryResponseWriter;

import org.apache.solr.response.RubyResponseWriter;

import org.apache.solr.response.SolrQueryResponse;

import org.apache.solr.response.XMLResponseWriter;

import org.apache.solr.servlet.SolrRequestParsers;

import org.dataone.configuration.Settings;

import org.xml.sax.SAXException;

import edu.ucsb.nceas.metacat.MetaCatServlet;

/**

 * This class will query the solr server and return the result.

 * @author tao

 *

 */

public class MetacatSolrIndex {

    public static final String SOLR_HOME_PROPERTY_NAME = "solr.homeDir";

    public static final String SOLR_CONFIG_FILE_NAME_PROPERTY_NAME = "solr.configFileName";

    public static final String SOLR_COLLECTION_NAME_PROPERTY_NAME = "solr.collectionName";

    public static final String SOLR_SERVER_CLASSNAME_PROPERTY_NAME = "solr.server.classname";

    private static final String WT = "wt";//the property name to specify the return type

    private static final String XML = "xml";

    private static final String JSON = "json";

    private static final String PYTHON = "python";

    private static final String RUBY = "ruby";

    private static final String PHP = "php";

    private static final String PHPS = "phps";

    private static final String VELOCITY = "velocity";

    private static final String CSV ="csv";

    private static Log log = LogFactory.getLog(MetacatSolrIndex.class);

    private CoreContainer coreContainer = null;

    private SolrServer solrServer = null;

    private String wt = null;//specify the return format.

    private String collectionName = null;

    /**

     * Constructor

     * @throws SAXException 

     * @throws IOException 

     * @throws ParserConfigurationException 

     */

    public MetacatSolrIndex() throws ParserConfigurationException, IOException, SAXException {

        generateEmbeddedServer();

    }

    /*

     * Generate the embedded solr server

     */

    private void generateEmbeddedServer() throws ParserConfigurationException, IOException, SAXException {

        String solrHomeDir = Settings.getConfiguration().getString(SOLR_HOME_PROPERTY_NAME);

        log.info("The configured solr home from properties is " + solrHomeDir);

        String configFileName = Settings.getConfiguration().getString(SOLR_CONFIG_FILE_NAME_PROPERTY_NAME);

        File configFile = new File(solrHomeDir, configFileName);

        coreContainer = new CoreContainer(solrHomeDir, configFile);

        coreContainer.load(solrHomeDir, configFile);

        collectionName = Settings.getConfiguration().getString(SOLR_COLLECTION_NAME_PROPERTY_NAME);

        solrServer = new EmbeddedSolrServer(coreContainer, collectionName);

    }

    /**

     * Query the solr server

     * @param query  the solr query

     * @return the result as the InputStream

     * @throws SolrServerException 

     */

    public InputStream query(String query) throws SolrServerException, IOException {

        InputStream inputStream = null;

        SolrParams solrParams = SolrRequestParsers.parseQueryString(query);

        wt = solrParams.get(WT);

        QueryResponse response = solrServer.query(solrParams);

        inputStream = transformResults(solrParams, response);

        return inputStream;

    }

    /*

     * Transform the Queryresponse to the InputStream

     */

    private InputStream transformResults(SolrParams request, QueryResponse response) throws SolrServerException, IOException {

        //InputStream stream = null;

        QueryResponseWriter writer = generateResponseWriter();

        Writer results = new StringWriter();

        SolrQueryResponse sResponse = new SolrQueryResponse();

        sResponse.setAllValues(response.getResponse());

        SolrCore core =coreContainer.getCore(collectionName);

        writer.write(results, new LocalSolrQueryRequest(core, request), sResponse);

        return new ByteArrayInputStream(results.toString().getBytes(MetaCatServlet.DEFAULT_ENCODING));

    }

    /* Here is the list of the handler class to handle different format.

     * <queryResponseWriter name="xml" default="true" class="solr.XMLResponseWriter" />

     * <queryResponseWriter name="json" class="solr.JSONResponseWriter"/>

     * <queryResponseWriter name="python" class="solr.PythonResponseWriter"/>

     * <queryResponseWriter name="ruby" class="solr.RubyResponseWriter"/>

     * <queryResponseWriter name="php" class="solr.PHPResponseWriter"/>

     * <queryResponseWriter name="phps" class="solr.PHPSerializedResponseWriter"/>

     * <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter"/>

     * <queryResponseWriter name="csv" class="solr.CSVResponseWriter"/>

     */

    private QueryResponseWriter generateResponseWriter() throws SolrServerException {

        QueryResponseWriter writer = null;

        if(wt == null || wt.trim().equals("") || wt.equals(XML)) {

            writer = new XMLResponseWriter();

        } else if(wt.equals(JSON)) {

            writer = new JSONResponseWriter();

        } else if(wt.equals(PYTHON)) {

            writer = new PythonResponseWriter();

        } else if(wt.equals(RUBY)) {

            writer = new RubyResponseWriter();

        } else if(wt.equals(PHP)) {

            writer = new PHPResponseWriter();

        } else if(wt.equals(PHPS)) {

            writer = new PHPSerializedResponseWriter();

        /*} else if(wt.equals(VELOCITY)) {

            writer = new VelocityResponseWriter();*/

        } else if(wt.equals(CSV)) {

            writer = new CSVResponseWriter();

        } else {

            throw new SolrServerException("Metacat doesn't support this response format "+wt);

        }

        return writer;

    }

}