Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A class to asyncronously do delta-T replication checking

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Chad Berkley

 *

 *   '$Author: daigle $'

 *     '$Date: 2009-08-24 14:34:17 -0700 (Mon, 24 Aug 2009) $'

 * '$Revision: 5030 $'

 *

 * 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.replication;

import edu.ucsb.nceas.metacat.AccessControlForSingleFile;

import edu.ucsb.nceas.metacat.CatalogMessageHandler;

import edu.ucsb.nceas.metacat.DBUtil;

import edu.ucsb.nceas.metacat.DocInfoHandler;

import edu.ucsb.nceas.metacat.DocumentImpl;

import edu.ucsb.nceas.metacat.DocumentImplWrapper;

import edu.ucsb.nceas.metacat.EventLog;

import edu.ucsb.nceas.metacat.database.DBConnection;

import edu.ucsb.nceas.metacat.database.DBConnectionPool;

import edu.ucsb.nceas.metacat.database.DatabaseService;

import edu.ucsb.nceas.metacat.properties.PropertyService;

import edu.ucsb.nceas.metacat.shared.HandlerException;

import edu.ucsb.nceas.metacat.util.MetacatUtil;

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

import java.sql.*;

import java.util.*;

import java.util.Date;

import java.io.*;

import java.net.*;

import java.text.*;

import org.apache.log4j.Logger;

import org.xml.sax.ContentHandler;

import org.xml.sax.ErrorHandler;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.XMLReaderFactory;

import org.xml.sax.helpers.DefaultHandler;

/**

 * This class handles deltaT replication checking.  Whenever this TimerTask

 * is fired it checks each server in xml_replication for updates and updates

 * the local db as needed.

 */

public class ReplicationHandler extends TimerTask

{

  int serverCheckCode = 1;

  ReplicationServerList serverList = null;

  //PrintWriter out;

//  private static final AbstractDatabase dbAdapter = MetacatUtil.dbAdapter;

  private static Logger logReplication = Logger.getLogger("ReplicationLogging");

  private static Logger logMetacat = Logger.getLogger(ReplicationHandler.class);

  private static int DOCINSERTNUMBER = 1;

  private static int DOCERRORNUMBER  = 1;

  private static int REVINSERTNUMBER = 1;

  private static int REVERRORNUMBER  = 1;

  public ReplicationHandler()

  {

    //this.out = o;

    serverList = new ReplicationServerList();

  }

  public ReplicationHandler(int serverCheckCode)

  {

    //this.out = o;

    this.serverCheckCode = serverCheckCode;

    serverList = new ReplicationServerList();

  }

  /**

   * Method that implements TimerTask.run().  It runs whenever the timer is

   * fired.

   */

  public void run()

  {

    //find out the last_checked time of each server in the server list and

    //send a query to each server to see if there are any documents in

    //xml_documents with an update_date > last_checked

      //if serverList is null, metacat don't need to replication

      if (serverList==null||serverList.isEmpty())

      {

        return;

      }

      updateCatalog();

      update();

      //conn.close();

  }

  /**

   * Method that uses revision taging for replication instead of update_date.

   */

  private void update()

  {

    /*

     Pseudo-algorithm

     - request a doc list from each server in xml_replication

     - check the rev number of each of those documents agains the

       documents in the local database

     - pull any documents that have a lesser rev number on the local server

       from the remote server

     - delete any documents that still exist in the local xml_documents but

       are in the deletedDocuments tag of the remote host response.

     - update last_checked to keep track of the last time it was checked.

       (this info is theoretically not needed using this system but probably

       should be kept anyway)

    */

    ReplicationServer replServer = null; // Variable to store the

                                        // ReplicationServer got from

                                        // Server list

    String server = null; // Variable to store server name

//    String update;

    Vector<String> responses = new Vector<String>();

    URL u;

    //Check for every server in server list to get updated list and put

    // them in to response

    for (int i=0; i<serverList.size(); i++)

    {

        // Get ReplicationServer object from server list

        replServer = serverList.serverAt(i);

        // Get server name from ReplicationServer object

        server = replServer.getServerName().trim();

        String result = null;

        logReplication.info("ReplicationHandler.update - full update started to: " + server);

        // Send command to that server to get updated docid information

        try

        {

          u = new URL("https://" + server + "?server="

          +MetacatUtil.getLocalReplicationServerName()+"&action=update");

          logReplication.info("ReplicationHandler.update - Sending infomation " +u.toString());

          result = ReplicationService.getURLContent(u);

        }

        catch (Exception e)

        {

          logMetacat.error("ReplicationHandler.update - " + ReplicationService.METACAT_REPL_ERROR_MSG);

          logReplication.error( "ReplicationHandler.update - Failed to get updated doc list "+

                       "for server " + server + " because "+e.getMessage());

          continue;

        }

        logReplication.info("docid: "+server+" "+result);

        //check if result have error or not, if has skip it.

        if (result.indexOf("<error>")!=-1 && result.indexOf("</error>")!=-1)

        {

          logMetacat.error("ReplicationHandler.update - " + ReplicationService.METACAT_REPL_ERROR_MSG);

          logReplication.error( "ReplicationHandler.update - Failed to get updated doc list "+

                       "for server " + server + " because "+result);

          continue;

        }

        //Add result to vector

        responses.add(result);

    }

    //make sure that there is updated file list

    //If response is null, metacat don't need do anything

    if (responses==null || responses.isEmpty())

    {

    	logMetacat.error("ReplicationHandler.update - " + ReplicationService.METACAT_REPL_ERROR_MSG);

        logReplication.info( "ReplicationHandler.update - No updated doc list for "+

                           "every server and failed to replicate");

        return;

    }

    logReplication.info("ReplicationHandler.update - Responses from remote metacat about updated "+

                   "document information: "+ responses.toString());

    // go through response vector(it contains updated vector and delete vector

    for(int i=0; i<responses.size(); i++)

    {

    	XMLReader parser;

    	ReplMessageHandler message = new ReplMessageHandler();

    	try

        {

          parser = initParser(message);

        }

        catch (Exception e)

        {

          logMetacat.error("ReplicationHandler.update - " + ReplicationService.METACAT_REPL_ERROR_MSG);

          logReplication.error("ReplicationHandler.update - Failed to replicate becaue couldn't " +

                                " initParser for message and " +e.getMessage());

           // stop replication

           return;

        }

        try

        {

          parser.parse(new InputSource(

                     new StringReader(

                     (String)(responses.elementAt(i)))));

        }

        catch(Exception e)

        {

          logMetacat.error("ReplicationHandler.update - " + ReplicationService.METACAT_REPL_ERROR_MSG);

          logReplication.error("ReplicationHandler.update - Couldn't parse one responses "+

                                   "because "+ e.getMessage());

          continue;

        }

        //v is the list of updated documents

        Vector<Vector<String>> updateList = new Vector<Vector<String>>(message.getUpdatesVect());

        logReplication.info("ReplicationHandler.update - The document list size is "+updateList.size()+ " from "+message.getServerName());

        //System.out.println("v: " + v.toString());

        //d is the list of deleted documents

        Vector<Vector<String>> deleteList = new Vector<Vector<String>>(message.getDeletesVect());

        //System.out.println("d: " + d.toString());

        logReplication.info("ReplicationHandler.update - Update vector size: "+ updateList.size()+" from "+message.getServerName());

        logReplication.info("ReplicationHandler.update - Delete vector size: "+ deleteList.size()+" from "+message.getServerName());

        logReplication.info("ReplicationHandler.update - The delete document list size is "+deleteList.size()+" from "+message.getServerName());

        // go though every element in updated document vector

        handleDocList(updateList, DocumentImpl.DOCUMENTTABLE);

        //handle deleted docs

        for(int k=0; k<deleteList.size(); k++)

        { //delete the deleted documents;

          Vector<String> w = new Vector<String>(deleteList.elementAt(k));

          String docId = (String)w.elementAt(0);

          try

          {

            handleDeleteSingleDocument(docId, server);

          }

          catch (Exception ee)

          {

            continue;

          }

        }//for delete docs

        // handle replicate doc in xml_revision

        Vector<Vector<String>> revisionList = new Vector<Vector<String>>(message.getRevisionsVect());

        logReplication.info("ReplicationHandler.update - The revision document list size is "+revisionList.size()+ " from "+message.getServerName());

        handleDocList(revisionList, DocumentImpl.REVISIONTABLE);

        DOCINSERTNUMBER = 1;

        DOCERRORNUMBER  = 1;

        REVINSERTNUMBER = 1;

        REVERRORNUMBER  = 1;

    }//for response

    //updated last_checked

    for (int i=0;i<serverList.size(); i++)

    {

       // Get ReplicationServer object from server list

       replServer = serverList.serverAt(i);

       try

       {

         updateLastCheckTimeForSingleServer(replServer);

       }

       catch(Exception e)

       {

         continue;

       }

    }//for

  }//update

  /* Handle replicate single xml document*/

  private void handleSingleXMLDocument(String remoteserver, String actions,

                                       String accNumber, String tableName)

               throws HandlerException

  {

    DBConnection dbConn = null;

    int serialNumber = -1;

    try

    {

      // Get DBConnection from pool

      dbConn=DBConnectionPool.

                  getDBConnection("ReplicationHandler.handleSingleXMLDocument");

      serialNumber=dbConn.getCheckOutSerialNumber();

      //if the document needs to be updated or inserted, this is executed

      String readDocURLString = "https://" + remoteserver + "?server="+

              MetacatUtil.getLocalReplicationServerName()+"&action=read&docid="+accNumber;

      readDocURLString = MetacatUtil.replaceWhiteSpaceForURL(readDocURLString);

      URL u = new URL(readDocURLString);

      // Get docid content

      String newxmldoc = ReplicationService.getURLContent(u);

      // If couldn't get skip it

      if ( newxmldoc.indexOf("<error>")!= -1 && newxmldoc.indexOf("</error>")!=-1)

      {

         throw new HandlerException("ReplicationHandler.handleSingleXMLDocument - " + newxmldoc);

      }

      //logReplication.info("xml documnet:");

      //logReplication.info(newxmldoc);

      // Try get the docid info from remote server

      DocInfoHandler dih = new DocInfoHandler();

      XMLReader docinfoParser = initParser(dih);

      String docInfoURLStr = "https://" + remoteserver +

                       "?server="+MetacatUtil.getLocalReplicationServerName()+

                       "&action=getdocumentinfo&docid="+accNumber;

      docInfoURLStr = MetacatUtil.replaceWhiteSpaceForURL(docInfoURLStr);

      URL docinfoUrl = new URL(docInfoURLStr);

      logReplication.info("ReplicationHandler.handleSingleXMLDocument - Sending message: " +

                                                  docinfoUrl.toString());

      String docInfoStr = ReplicationService.getURLContent(docinfoUrl);

      docinfoParser.parse(new InputSource(new StringReader(docInfoStr)));

      Hashtable<String, String> docinfoHash = dih.getDocInfo();

      // Get home server of the docid

      String docHomeServer = docinfoHash.get("home_server");

      logReplication.info("ReplicationHandler.handleSingleXMLDocument - doc home server in repl: "+docHomeServer);

      String createdDate = docinfoHash.get("date_created");

      String updatedDate = docinfoHash.get("date_updated");

      //docid should include rev number too

      /*String accnum=docId+util.getProperty("document.accNumSeparator")+

                                              (String)docinfoHash.get("rev");*/

      logReplication.info("ReplicationHandler.handleSingleXMLDocument - docid in repl: "+accNumber);

      String docType = docinfoHash.get("doctype");

      logReplication.info("ReplicationHandler.handleSingleXMLDocument - doctype in repl: "+docType);

      String parserBase = null;

      // this for eml2 and we need user eml2 parser

      if (docType != null && (docType.trim()).equals(DocumentImpl.EML2_0_0NAMESPACE))

      {

         parserBase = DocumentImpl.EML200;

      }

      else if (docType != null && (docType.trim()).equals(DocumentImpl.EML2_0_1NAMESPACE))

      {

        parserBase = DocumentImpl.EML200;

      }

      else if (docType != null && (docType.trim()).equals(DocumentImpl.EML2_1_0NAMESPACE))

      {

        parserBase = DocumentImpl.EML210;

      }

      // Write the document into local host

      DocumentImplWrapper wrapper = new DocumentImplWrapper(parserBase, false);

      String newDocid = wrapper.writeReplication(dbConn,

                              new StringReader(newxmldoc),

                              docinfoHash.get("public_access"),

                              null,  /* the dtd text */

                              actions,

                              accNumber,

                              docinfoHash.get("user_owner"),

                              null, /* null for groups[] */

                              docHomeServer,

                              remoteserver, tableName, true,// true is for time replication 

                              createdDate,

                              updatedDate);

      //process extra access rules

      Vector<AccessControlForSingleFile> accessControlList = dih.getAccessControlList();

      if (accessControlList != null) {

    	  for (AccessControlForSingleFile acfsf : accessControlList) {

        	  if (!acfsf.accessControlExists()) {

        		  acfsf.insertPermissions();

        	  }

          }

      }

      logReplication.info("ReplicationHandler.handleSingleXMLDocument - Successfully replicated doc " + accNumber);

      if (tableName.equals(DocumentImpl.DOCUMENTTABLE))

      {

        logReplication.info("ReplicationHandler.handleSingleXMLDocument - " + DOCINSERTNUMBER + " Wrote xml doc " + accNumber +

                                     " into "+tableName + " from " +

                                         remoteserver);

        DOCINSERTNUMBER++;

      }

      else

      {

          logReplication.info("ReplicationHandler.handleSingleXMLDocument - " +REVINSERTNUMBER + " Wrote xml doc " + accNumber +

                  " into "+tableName + " from " +

                      remoteserver);

          REVINSERTNUMBER++;

      }

      String ip = getIpFromURL(u);

      EventLog.getInstance().log(ip, ReplicationService.REPLICATIONUSER, accNumber, actions);

    }//try

    catch(Exception e)

    {

        if (tableName.equals(DocumentImpl.DOCUMENTTABLE))

        {

        	logMetacat.error("ReplicationHandler.handleSingleXMLDocument - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

        	logReplication.error("ReplicationHandler.handleSingleXMLDocument - " +DOCERRORNUMBER + " Failed to write xml doc " + accNumber +

                                       " into "+tableName + " from " +

                                           remoteserver + " because "+e.getMessage());

          DOCERRORNUMBER++;

        }

        else

        {

        	logMetacat.error("ReplicationHandler.handleSingleXMLDocument - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

        	logReplication.error("ReplicationHandler.handleSingleXMLDocument - " +REVERRORNUMBER + " Failed to write xml doc " + accNumber +

                    " into "+tableName + " from " +

                        remoteserver +" because "+e.getMessage());

            REVERRORNUMBER++;

        }

        logMetacat.error("ReplicationHandler.handleSingleXMLDocument - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

        logReplication.error("ReplicationHandler.handleSingleXMLDocument - Failed to write doc " + accNumber +

                                      " into db because " +e.getMessage());

      throw new HandlerException("ReplicationHandler.handleSingleXMLDocument - generic exception " 

    		  + "writing Replication: " +e.getMessage());

    }

    finally

    {

       //return DBConnection

       DBConnectionPool.returnDBConnection(dbConn, serialNumber);

    }//finally

  }

  /* Handle replicate single xml document*/

  private void handleSingleDataFile(String remoteserver, String actions,

                                    String accNumber, String tableName)

               throws HandlerException

  {

    logReplication.info("ReplicationHandler.handleSingleDataFile - Try to replicate data file: " + accNumber);

    DBConnection dbConn = null;

    int serialNumber = -1;

    try

    {

      // Get DBConnection from pool

      dbConn=DBConnectionPool.

                  getDBConnection("ReplicationHandler.handleSinlgeDataFile");

      serialNumber=dbConn.getCheckOutSerialNumber();

      // Try get docid info from remote server

      DocInfoHandler dih = new DocInfoHandler();

      XMLReader docinfoParser = initParser(dih);

      String docInfoURLString = "https://" + remoteserver +

                  "?server="+MetacatUtil.getLocalReplicationServerName()+

                  "&action=getdocumentinfo&docid="+accNumber;

      docInfoURLString = MetacatUtil.replaceWhiteSpaceForURL(docInfoURLString);

      URL docinfoUrl = new URL(docInfoURLString);

      String docInfoStr = ReplicationService.getURLContent(docinfoUrl);

      docinfoParser.parse(new InputSource(new StringReader(docInfoStr)));

      Hashtable<String, String> docinfoHash = dih.getDocInfo();

      // Get doicd owner

      String user = docinfoHash.get("user_owner");

      // Get docid name (such as acl or dataset)

      String docName = docinfoHash.get("docname");

      // Get doc type (eml public id)

      String docType = docinfoHash.get("doctype");

      // Get docid home sever. it might be different to remoteserver

      // becuause of hub feature

      String docHomeServer = docinfoHash.get("home_server");

      String createdDate = docinfoHash.get("date_created");

      String updatedDate = docinfoHash.get("date_updated");

      //docid should include rev number too

      /*String accnum=docId+util.getProperty("document.accNumSeparator")+

                                              (String)docinfoHash.get("rev");*/

      String datafilePath = PropertyService.getProperty("application.datafilepath");

      // Get data file content

      String readDataURLString = "https://" + remoteserver + "?server="+

                                        MetacatUtil.getLocalReplicationServerName()+

                                            "&action=readdata&docid="+accNumber;

      readDataURLString = MetacatUtil.replaceWhiteSpaceForURL(readDataURLString);

      URL u = new URL(readDataURLString);

      InputStream input = u.openStream();

      //register data file into xml_documents table and wite data file

      //into file system

      if ( input != null)

      {

        DocumentImpl.writeDataFileInReplication(input,

                                                datafilePath,

                                                docName,docType,

                                                accNumber, user,

                                                docHomeServer,

                                                remoteserver,

                                                tableName,

                                                true, //true means timed replication

                                                createdDate,

                                                updatedDate);

        //process extra access rules

        Vector<AccessControlForSingleFile> accessControlList = dih.getAccessControlList();

        if (accessControlList != null) {

      	  for (AccessControlForSingleFile acfsf : accessControlList) {

          	  if (!acfsf.accessControlExists()) {

          		acfsf.insertPermissions();

          	  }

            }

        }

        logReplication.info("ReplicationHandler.handleSingleDataFile - Successfully to write datafile " + accNumber);

        /*MetacatReplication.replLog("wrote datafile " + accNumber + " from " +

                                    remoteserver);*/

        if (tableName.equals(DocumentImpl.DOCUMENTTABLE))

        {

          logReplication.info("ReplicationHandler.handleSingleDataFile - " + DOCINSERTNUMBER + " Wrote data file" + accNumber +

                                       " into "+tableName + " from " +

                                           remoteserver);

          DOCINSERTNUMBER++;

        }

        else

        {

            logReplication.info("ReplicationHandler.handleSingleDataFile - " + REVINSERTNUMBER + " Wrote data file" + accNumber +

                    " into "+tableName + " from " +

                        remoteserver);

            REVINSERTNUMBER++;

        }

        String ip = getIpFromURL(u);

        EventLog.getInstance().log(ip, ReplicationService.REPLICATIONUSER, accNumber, actions);

      }//if

      else

      {

         logReplication.info("ReplicationHandler.handleSingleDataFile - Couldn't open the data file: " + accNumber);

         throw new HandlerException("ReplicationHandler.handleSingleDataFile - Couldn't open the data file: " + accNumber);

      }//else

    }//try

    catch(Exception e)

    {

      /*MetacatReplication.replErrorLog("Failed to try wrote datafile " + accNumber +

                                      " because " +e.getMessage());*/

      if (tableName.equals(DocumentImpl.DOCUMENTTABLE))

      {

    	logMetacat.error("ReplicationHandler.handleSingleDataFile - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

    	logReplication.error("ReplicationHandler.handleSingleDataFile - " + DOCERRORNUMBER + " Failed to write data file " + accNumber +

                                     " into " + tableName + " from " +

                                         remoteserver + " because " + e.getMessage());

        DOCERRORNUMBER++;

      }

      else

      {

    	  logMetacat.error("ReplicationHandler.handleSingleDataFile - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

    	  logReplication.error("ReplicationHandler.handleSingleDataFile - " + REVERRORNUMBER + " Failed to write data file" + accNumber +

                  " into " + tableName + " from " +

                      remoteserver +" because "+ e.getMessage());

          REVERRORNUMBER++;

      }

      logMetacat.error("ReplicationHandler.handleSingleDataFile - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

      logReplication.error("ReplicationHandler.handleSingleDataFile - Failed to try wrote datafile " + accNumber +

                                      " because " + e.getMessage());

      throw new HandlerException("ReplicationHandler.handleSingleDataFile - generic exception " 

    		  + "writing Replication: " + e.getMessage());

    }

    finally

    {

       //return DBConnection

       DBConnectionPool.returnDBConnection(dbConn, serialNumber);

    }//finally

  }

  /* Handle delete single document*/

  private void handleDeleteSingleDocument(String docId, String notifyServer)

               throws HandlerException

  {

    logReplication.info("ReplicationHandler.handleDeleteSingleDocument - Try delete doc: "+docId);

    DBConnection dbConn = null;

    int serialNumber = -1;

    try

    {

      // Get DBConnection from pool

      dbConn=DBConnectionPool.

                  getDBConnection("ReplicationHandler.handleDeleteSingleDoc");

      serialNumber=dbConn.getCheckOutSerialNumber();

      if(!alreadyDeleted(docId))

      {

         //because delete method docid should have rev number

         //so we just add one for it. This rev number is no sence.

         String accnum=docId+PropertyService.getProperty("document.accNumSeparator")+"1";

         //System.out.println("accnum: "+accnum);

         DocumentImpl.delete(accnum, null, null, notifyServer);

         logReplication.info("ReplicationHandler.handleDeleteSingleDocument - Successfully deleted doc " + docId);

         logReplication.info("ReplicationHandler.handleDeleteSingleDocument - Doc " + docId + " deleted");

         URL u = new URL("https://"+notifyServer);

         String ip = getIpFromURL(u);

         EventLog.getInstance().log(ip, ReplicationService.REPLICATIONUSER, docId, "delete");

      }

    }//try

    catch(Exception e)

    {

      logMetacat.error("ReplicationHandler.handleDeleteSingleDocument - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

      logReplication.error("ReplicationHandler.handleDeleteSingleDocument - Failed to delete doc " + docId +

                                 " in db because because " + e.getMessage());

      throw new HandlerException("ReplicationHandler.handleDeleteSingleDocument - generic exception " 

    		  + "when handling document: " + e.getMessage());

    }

    finally

    {

       //return DBConnection

       DBConnectionPool.returnDBConnection(dbConn, serialNumber);

    }//finally

  }

  /* Handle updateLastCheckTimForSingleServer*/

  private void updateLastCheckTimeForSingleServer(ReplicationServer repServer)

                                                  throws HandlerException

  {

    String server = repServer.getServerName();

    DBConnection dbConn = null;

    int serialNumber = -1;

    PreparedStatement pstmt = null;

    try

    {

      // Get DBConnection from pool

      dbConn=DBConnectionPool.

             getDBConnection("ReplicationHandler.updateLastCheckTimeForServer");

      serialNumber=dbConn.getCheckOutSerialNumber();

      logReplication.info("ReplicationHandler.updateLastCheckTimeForSingleServer - Try to update last_check for server: "+server);

      // Get time from remote server

      URL dateurl = new URL("https://" + server + "?server="+

      MetacatUtil.getLocalReplicationServerName()+"&action=gettime");

      String datexml = ReplicationService.getURLContent(dateurl);

      logReplication.info("ReplicationHandler.updateLastCheckTimeForSingleServer - datexml: "+datexml);

      if (datexml!=null && !datexml.equals(""))

      {

         String datestr = datexml.substring(11, datexml.indexOf('<', 11));

         StringBuffer sql = new StringBuffer();

         /*sql.append("update xml_replication set last_checked = to_date('");

         sql.append(datestr).append("', 'YY-MM-DD HH24:MI:SS') where ");

         sql.append("server like '").append(server).append("'");*/

         sql.append("update xml_replication set last_checked = ");

         sql.append(DatabaseService.getDBAdapter().toDate(datestr, "MM/DD/YY HH24:MI:SS"));

         sql.append(" where server like '").append(server).append("'");

         pstmt = dbConn.prepareStatement(sql.toString());

         pstmt.executeUpdate();

         dbConn.commit();

         pstmt.close();

         logReplication.info("ReplicationHandler.updateLastCheckTimeForSingleServer - last_checked updated to "+datestr+" on "

                                      + server);

      }//if

      else

      {

         logReplication.info("ReplicationHandler.updateLastCheckTimeForSingleServer - Failed to update last_checked for server "  +

                                  server + " in db because couldn't get time "

                                  );

         throw new Exception("Couldn't get time for server "+ server);

      }

    }//try

    catch(Exception e)

    {

      logMetacat.error("ReplicationHandler.updateLastCheckTimeForSingleServer - " + ReplicationService.METACAT_REPL_ERROR_MSG); 

      logReplication.error("ReplicationHandler.updateLastCheckTimeForSingleServer - Failed to update last_checked for server " +

                                server + " in db because because " + e.getMessage());

      throw new HandlerException("ReplicationHandler.updateLastCheckTimeForSingleServer - " 

    		  + "Error updating last checked time: " + e.getMessage());

    }

    finally

    {

       //return DBConnection

       DBConnectionPool.returnDBConnection(dbConn, serialNumber);

    }//finally

  }

  /**

   * updates xml_catalog with entries from other servers.

   */

  private void updateCatalog()

  {

    logReplication.info("ReplicationHandler.updateCatalog - Start of updateCatalog");

    // ReplicationServer object in server list

    ReplicationServer replServer = null;

    PreparedStatement pstmt = null;

    String server = null;

    // Go through each ReplicationServer object in sererlist

    for (int j=0; j<serverList.size(); j++)

    {

      Vector<Vector<String>> remoteCatalog = new Vector<Vector<String>>();

      Vector<String> publicId = new Vector<String>();

      try

      {

        // Get ReplicationServer object from server list

        replServer = serverList.serverAt(j);

        // Get server name from the ReplicationServer object

        server = replServer.getServerName();

        // Try to get catalog

        URL u = new URL("https://" + server + "?server="+

        MetacatUtil.getLocalReplicationServerName()+"&action=getcatalog");

        logReplication.info("ReplicationHandler.updateCatalog - sending message " + u.toString());

        String catxml = ReplicationService.getURLContent(u);

        // Make sure there are not error, no empty string

        if (catxml.indexOf("error")!=-1 || catxml==null||catxml.equals(""))

        {

          throw new Exception("Couldn't get catalog list form server " +server);

        }

        logReplication.info("ReplicationHandler.updateCatalog - catxml: " + catxml);

        CatalogMessageHandler cmh = new CatalogMessageHandler();

        XMLReader catparser = initParser(cmh);

        catparser.parse(new InputSource(new StringReader(catxml)));

        //parse the returned catalog xml and put it into a vector

        remoteCatalog = cmh.getCatalogVect();

        // Makse sure remoteCatalog is not empty

        if (remoteCatalog.isEmpty())

        {

          throw new Exception("Couldn't get catalog list form server " +server);

        }

        String localcatxml = ReplicationService.getCatalogXML();

        // Make sure local catalog is no empty

        if (localcatxml==null||localcatxml.equals(""))

        {

          throw new Exception("Couldn't get catalog list form server " +server);

        }

        cmh = new CatalogMessageHandler();

        catparser = initParser(cmh);

        catparser.parse(new InputSource(new StringReader(localcatxml)));

        Vector<Vector<String>> localCatalog = cmh.getCatalogVect();

        //now we have the catalog from the remote server and this local server

        //we now need to compare the two and merge the differences.

        //the comparison is base on the public_id fields which is the 4th

        //entry in each row vector.

        publicId = new Vector<String>();

        for(int i=0; i<localCatalog.size(); i++)

        {

          Vector<String> v = new Vector<String>(localCatalog.elementAt(i));

          logReplication.info("ReplicationHandler.updateCatalog - v1: " + v.toString());

          publicId.add(new String((String)v.elementAt(3)));

          //System.out.println("adding " + (String)v.elementAt(3));

        }

      }//try

      catch (Exception e)

      {

        logMetacat.error("ReplicationHandler.updateCatalog - " + ReplicationService.METACAT_REPL_ERROR_MSG);                         

        logReplication.error("ReplicationHandler.updateCatalog - Failed to update catalog for server "+

                                    server + " because " +e.getMessage());

      }//catch

      for(int i=0; i<remoteCatalog.size(); i++)

      {

         // DConnection

        DBConnection dbConn = null;

        // DBConnection checkout serial number

        int serialNumber = -1;

        try

        {

            dbConn=DBConnectionPool.

                  getDBConnection("ReplicationHandler.updateCatalog");

            serialNumber=dbConn.getCheckOutSerialNumber();

            Vector<String> v = remoteCatalog.elementAt(i);

            //System.out.println("v2: " + v.toString());

            //System.out.println("i: " + i);

            //System.out.println("remoteCatalog.size(): " + remoteCatalog.size());

            //System.out.println("publicID: " + publicId.toString());

            logReplication.info

                              ("ReplicationHandler.updateCatalog - v.elementAt(3): " + (String)v.elementAt(3));

           if(!publicId.contains(v.elementAt(3)))

           { //so we don't have this public id in our local table so we need to

             //add it.

             //System.out.println("in if");

             StringBuffer sql = new StringBuffer();

             sql.append("insert into xml_catalog (entry_type, source_doctype, ");

             sql.append("target_doctype, public_id, system_id) values (?,?,?,");

             sql.append("?,?)");

             //System.out.println("sql: " + sql.toString());

             pstmt = dbConn.prepareStatement(sql.toString());

             pstmt.setString(1, (String)v.elementAt(0));

             pstmt.setString(2, (String)v.elementAt(1));

             pstmt.setString(3, (String)v.elementAt(2));

             pstmt.setString(4, (String)v.elementAt(3));

             pstmt.setString(5, (String)v.elementAt(4));

             pstmt.execute();

             pstmt.close();

             logReplication.info("ReplicationHandler.updateCatalog - Success fully to insert new publicid "+

                               (String)v.elementAt(3) + " from server"+server);

           }

        }

        catch(Exception e)

        {

           logMetacat.error("ReplicationHandler.updateCatalog - " + ReplicationService.METACAT_REPL_ERROR_MSG);                         

           logReplication.error("ReplicationHandler.updateCatalog - Failed to update catalog for server "+

                                    server + " because " +e.getMessage());

        }//catch

        finally

        {

           DBConnectionPool.returnDBConnection(dbConn, serialNumber);

        }//finall

      }//for remote catalog

    }//for server list

    logReplication.info("End of updateCatalog");

  }

  /**

   * Method that returns true if docid has already been "deleted" from metacat.

   * This method really implements a truth table for deleted documents

   * The table is (a docid in one of the tables is represented by the X):

   * xml_docs      xml_revs      deleted?

   * ------------------------------------

   *   X             X             FALSE

   *   X             _             FALSE

   *   _             X             TRUE

   *   _             _             TRUE

   */

  private static boolean alreadyDeleted(String docid) throws HandlerException

  {

    DBConnection dbConn = null;

    int serialNumber = -1;

    PreparedStatement pstmt = null;

    try

    {

      dbConn=DBConnectionPool.

                  getDBConnection("ReplicationHandler.alreadyDeleted");

      serialNumber=dbConn.getCheckOutSerialNumber();

      boolean xml_docs = false;

      boolean xml_revs = false;

      StringBuffer sb = new StringBuffer();

      sb.append("select docid from xml_revisions where docid like '");

      sb.append(docid).append("'");

      pstmt = dbConn.prepareStatement(sb.toString());

      pstmt.execute();

      ResultSet rs = pstmt.getResultSet();

      boolean tablehasrows = rs.next();

      if(tablehasrows)

      {

        xml_revs = true;

      }

      sb = new StringBuffer();

      sb.append("select docid from xml_documents where docid like '");

      sb.append(docid).append("'");

      pstmt.close();

      pstmt = dbConn.prepareStatement(sb.toString());

      //increase usage count

      dbConn.increaseUsageCount(1);

      pstmt.execute();

      rs = pstmt.getResultSet();

      tablehasrows = rs.next();

      pstmt.close();

      if(tablehasrows)

      {

        xml_docs = true;

      }

      if(xml_docs && xml_revs)