Metacat

/**

 *   '$Author: bojilova $'

 *     '$Date: 2001-08-08 12:56:35 -0700 (Wed, 08 Aug 2001) $'

 * '$Revision: 819 $'

 *

 * 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;

import java.sql.*;

import java.util.*;

import java.net.*;

public class RelationHandler //implements Runnable

{

  private Thread btThread = null;

  private Connection conn = null;

  private String docid = null;

  MetaCatUtil util = new MetaCatUtil();

  /** 

   * Constructor for this class.  finds all of the relations to a single xml

   * document and writes them to the database.  This includes transitive

   * relations.

   * @param docid the ID of the XML document to index.

   */

  public RelationHandler(String docid, Connection conn)

              throws McdbException, SQLException, AccessionNumberException

  {

    this.conn = conn;

    this.docid = docid;

    putRelations();

  }

  /**

   * insert the relations specified in the triples into xml_relation table

   */ 

  private void putRelations() 

              throws McdbException, SQLException, AccessionNumberException

  {

    String packagetype = null;

    String subject = null;

    String subDoctype = null;

    String relationship = null;

    String object = null;

    String objDoctype = null;

    PreparedStatement pstmt = null; // to get the relations from xml_nodes

    PreparedStatement tstmt = null; // to insert each relation into xml_relation

    MetaCatUtil.debugMessage("Running relation handler!");

    /* 

     * PSEUDO-CODE ALGORITHM:

     * deletes all of the relations with a docid of @docid.

     * for each new relation r in xml_nodes

     *   put r into xml_relation

     */

    //DocumentImpl xmldoc = new DocumentImpl(conn,docid,false);

    packagetype = (new DocumentImpl(conn,docid,false)).getDoctype();

    // first delete the relations for this package document if any

    deleteRelations(docid);

    // to put the new relations get them out of xml_nodes

    pstmt = conn.prepareStatement(QuerySpecification.printPackageSQL(docid));

    pstmt.execute();

    ResultSet rs = pstmt.getResultSet();

    boolean hasmorerows = rs.next();

    if (hasmorerows) {

      tstmt = conn.prepareStatement("INSERT INTO xml_relation (" +

                                    "docid,packagetype,subject,subdoctype," +

                                    "relationship, object, objdoctype) " + 

                                    "VALUES (?, ?, ?, ?, ?, ?, ?)");

    }

    while(hasmorerows) {

      subject = rs.getString(1);

      relationship = rs.getString(2);

      object = rs.getString(3);

      // cut out the revision number for subject and object

      subject = (new DocumentIdentifier(subject)).getIdentifier();

      object = (new DocumentIdentifier(object)).getIdentifier();

      //subDoctype and objDoctype are N/A

      subDoctype = null;

      objDoctype = null;

      //put the new relation into xml_relation

      tstmt.setString(1, docid);

      tstmt.setString(2, packagetype);

      tstmt.setString(3, subject);

      tstmt.setString(4, subDoctype);

      tstmt.setString(5, relationship);

      tstmt.setString(6, object);

      tstmt.setString(7, objDoctype);

      tstmt.execute(); 

      hasmorerows = rs.next();

    }

    if ( tstmt != null ) {

      tstmt.close();

    }

    pstmt.close();

    conn.commit();

  }

  /**

   * Deletes all of the relations with a docid of 'docid'.

   * @param docid the docid of the package which relations to delete.

   */

  public void deleteRelations(String docid) throws SQLException

  {

    try {

      PreparedStatement pstmt = conn.prepareStatement(

                                "DELETE FROM xml_relation " +

                                "WHERE docid = '" + docid + "'");

      pstmt.execute();

      pstmt.close();

    } catch(SQLException e) {

      MetaCatUtil.debugMessage("error in RelationHandler.deleteRelations(): " + 

                          e.getMessage());

      System.out.println("error in RelationHandler.deleteRelations(): " + 

                          e.getMessage());

      throw e;

    }

  }

  /**

   * Get the access file id for a package

   * @param docid the document identifier of the package

   * @return the document identifier of the access file for that package

   */

  public String getAccessFileID(String docid) throws SQLException

  {

    String aclid = null;

    PreparedStatement pstmt = 

      conn.prepareStatement("SELECT docid FROM xml_documents " +

                            "WHERE docid in " +

                            "(SELECT subject FROM xml_relation " +

                            "WHERE docid = ?) " +

                            "AND doctype = ?");

    pstmt.setString(1, docid);

    pstmt.setString(2, MetaCatUtil.getOption("accessdoctype"));

    pstmt.execute();

    ResultSet rs = pstmt.getResultSet();

    boolean hasRow = rs.next();

    if (hasRow) {

      aclid = rs.getString(1);

    }

    pstmt.close();

    return aclid;

  }

}