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/**
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* '$RCSfile$'
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* Purpose: A class to asyncronously do delta-T replication checking
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* Authors: Chad Berkley
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* Release: @release@
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*
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* '$Author: berkley $'
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* '$Date: 2000-12-12 10:55:33 -0800 (Tue, 12 Dec 2000) $'
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* '$Revision: 595 $'
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*/
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package edu.ucsb.nceas.metacat;
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import java.sql.*;
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import java.util.*;
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import java.lang.Thread;
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import java.io.*;
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import java.net.*;
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import java.text.*;
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import org.xml.sax.AttributeList;
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import org.xml.sax.ContentHandler;
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import org.xml.sax.DTDHandler;
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import org.xml.sax.EntityResolver;
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import org.xml.sax.ErrorHandler;
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import org.xml.sax.InputSource;
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import org.xml.sax.XMLReader;
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import org.xml.sax.SAXException;
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import org.xml.sax.SAXParseException;
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import org.xml.sax.helpers.XMLReaderFactory;
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import org.xml.sax.helpers.DefaultHandler;
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/**
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* This class handles deltaT replication checking. Whenever this TimerTask
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* is fired it checks each server in xml_replication for updates and updates
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* the local db as needed.
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*/
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public class ReplicationHandler extends TimerTask
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{
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int serverCheckCode = 1;
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MetaCatUtil util = new MetaCatUtil();
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Hashtable serverList = new Hashtable();
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Connection conn;
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PrintWriter out;
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public ReplicationHandler(PrintWriter o)
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{
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this.out = o;
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}
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public ReplicationHandler(PrintWriter o, int serverCheckCode)
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{
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this.out = o;
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this.serverCheckCode = serverCheckCode;
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}
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/**
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* Method that implements TimerTask.run(). It runs whenever the timer is
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* fired.
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*/
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public void run()
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{
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//find out the last_checked time of each server in the server list and
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//send a query to each server to see if there are any documents in
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//xml_documents with an update_date > last_checked
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try
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{
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conn = util.openDBConnection();
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serverList = buildServerList(conn);
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update(serverList, conn);
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updateCatalog(serverList, conn);
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conn.close();
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}
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catch (Exception e)
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{
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System.out.println("Error in replicationHandler.run(): " + e.getMessage());
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}
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}
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/**
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* Method that uses revision taging for replication instead of update_date.
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*/
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private void update(Hashtable serverList, Connection conn)
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{
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/*
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Pseudo-algorithm
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- request a doc list from each server in xml_replication
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- check the rev number of each of those documents agains the
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documents in the local database
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- pull any documents that have a lesser rev number on the local server
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from the remote server
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- delete any documents that still exist in the local xml_documents but
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are in the deletedDocuments tag of the remote host response.
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- update last_checked to keep track of the last time it was checked.
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(this info is theoretically not needed using this system but probably
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should be kept anyway)
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*/
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Enumeration keys;
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String server;
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String update;
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ReplMessageHandler message = new ReplMessageHandler();
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Vector responses = new Vector();
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PreparedStatement pstmt;
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ResultSet rs;
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boolean tablehasrows;
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boolean flag=false;
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String action = new String();
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XMLReader parser;
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URL u;
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try
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{
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MetaCatUtil.debugMessage("init parser");
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parser = initParser(message);
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keys = serverList.keys();
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while(keys.hasMoreElements())
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{
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server = (String)(keys.nextElement());
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MetacatReplication.replLog("full update started to: " + server);
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u = new URL("http://" + server + "?action=update");
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System.out.println("Sending Message: " + u.toString());
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String result = MetacatReplication.getURLContent(u);
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responses.add(result);
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}
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System.out.println("responses: " + responses.toString());
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for(int i=0; i<responses.size(); i++)
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{ //check each server for updated files
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//System.out.println("parsing responses");
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parser.parse(new InputSource(
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new StringReader(
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(String)(responses.elementAt(i)))));
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Vector v = new Vector(message.getUpdatesVect());
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//System.out.println("v: " + v.toString());
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Vector d = new Vector(message.getDeletesVect());
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//check the revs in u to see if there are any newer ones than
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//in the local DB.
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for(int j=0; j<v.size(); j++)
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{
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Vector w = new Vector((Vector)(v.elementAt(j)));
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//System.out.println("w: " + w.toString());
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String docid = (String)w.elementAt(0);
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//System.out.println("docid: " + docid);
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int rev = Integer.parseInt((String)w.elementAt(1));
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//System.out.println("rev: " + rev);
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String docServer = (String)w.elementAt(2);
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//System.out.println("docServer: " + docServer);
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pstmt = conn.prepareStatement("select rev from xml_documents where "+
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"docid like '" + docid + "'");
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pstmt.execute();
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rs = pstmt.getResultSet();
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tablehasrows = rs.next();
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if(tablehasrows)
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{ //check the revs for an update because this document is in the
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//local DB, it just might be out of date.
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int localrev = rs.getInt(1);
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if(localrev == rev)
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{
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flag = false;
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}
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else if(localrev < rev)
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{//this document needs to be updated so send an read request
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action = "UPDATE";
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flag = true;
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}
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}
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else
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{ //insert this document as new because it is not in the local DB
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action = "INSERT";
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flag = true;
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}
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if(flag)
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{ //if the document needs to be updated or inserted, this is executed
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u = new URL("http://" + docServer + "?action=read&docid=" +
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docid);
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System.out.println("Sending message: " + u.toString());
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String newxmldoc = MetacatReplication.getURLContent(u);
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DocInfoHandler dih = new DocInfoHandler();
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XMLReader docinfoParser = initParser(dih);
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URL docinfoUrl = new URL("http://" + docServer +
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"?action=getdocumentinfo&docid=" +
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docid);
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System.out.println("Sending message: " + docinfoUrl.toString());
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String docInfoStr = MetacatReplication.getURLContent(docinfoUrl);
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docinfoParser.parse(new InputSource(new StringReader(docInfoStr)));
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Hashtable docinfoHash = dih.getDocInfo();
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int serverCode = MetacatReplication.getServerCode(docServer);
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MetaCatUtil.debugMessage("updating doc: " + docid + " action: "+ action);
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String newDocid = DocumentImpl.write(conn,
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new StringReader(newxmldoc),
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null,
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action,
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docid,
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(String)docinfoHash.get("user_owner"),
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(String)docinfoHash.get("user_owner"),
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serverCode,
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true);
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MetacatReplication.replLog("wrote doc " + docid + " from " +
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docServer);
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System.out.println("wrote doc " + docid + " from " +
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docServer);
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}
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}
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for(int k=0; k<d.size(); k++)
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{ //delete the deleted documents;
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Vector w = new Vector((Vector)d.elementAt(k));
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String docid = (String)w.elementAt(0);
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if(!alreadyDeleted(docid, conn))
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{
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DocumentImpl.delete(conn, docid, null, null);
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System.out.println("Document " + docid + " deleted.");
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MetacatReplication.replLog("doc " + docid + " deleted");
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}
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}
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keys = serverList.keys();
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while(keys.hasMoreElements())
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{
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server = (String)(keys.nextElement());
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URL dateurl = new URL("http://" + server + "?action=gettime");
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String datexml = MetacatReplication.getURLContent(dateurl);
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String datestr = datexml.substring(11, datexml.indexOf('<', 11));
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StringBuffer sql = new StringBuffer();
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sql.append("update xml_replication set last_checked = to_date('");
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sql.append(datestr).append("', 'YY-MM-DD HH24:MI:SS') where ");
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sql.append("server like '").append(server).append("'");
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//System.out.println("sql: " + sql.toString());
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pstmt = conn.prepareStatement(sql.toString());
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pstmt.executeUpdate();
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//conn.commit();
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System.out.println("last_checked updated to " + datestr + " on " +
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server);
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}
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}
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}
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catch(Exception e)
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{
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System.out.println("error in update2: " + e.getMessage());
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e.printStackTrace(System.out);
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}
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}
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/**
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* updates xml_catalog with entries from other servers.
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*/
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private void updateCatalog(Hashtable serverList, Connection conn)
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{
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System.out.println("in updateCatalog");
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try
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{
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String server;
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Enumeration keys = serverList.keys();
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while(keys.hasMoreElements())
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{ //go through each server
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server = (String)(keys.nextElement());
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URL u = new URL("http://" + server + "?action=getcatalog");
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System.out.println("sending message " + u.toString());
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String catxml = MetacatReplication.getURLContent(u);
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//System.out.println("catxml: " + catxml);
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CatalogMessageHandler cmh = new CatalogMessageHandler();
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XMLReader catparser = initParser(cmh);
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catparser.parse(new InputSource(new StringReader(catxml)));
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//parse the returned catalog xml and put it into a vector
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Vector remoteCatalog = cmh.getCatalogVect();
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String localcatxml = MetacatReplication.getCatalogXML();
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//System.out.println("localcatxml: " + localcatxml);
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cmh = new CatalogMessageHandler();
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catparser = initParser(cmh);
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catparser.parse(new InputSource(new StringReader(localcatxml)));
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Vector localCatalog = cmh.getCatalogVect();
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//now we have the catalog from the remote server and this local server
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//we now need to compare the two and merge the differences.
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//the comparison is base on the public_id fields which is the 4th
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//entry in each row vector.
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Vector publicId = new Vector();
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for(int i=0; i<localCatalog.size(); i++)
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{
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Vector v = new Vector((Vector)localCatalog.elementAt(i));
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//System.out.println("v1: " + v.toString());
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publicId.add(new String((String)v.elementAt(3)));
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//System.out.println("adding " + (String)v.elementAt(3));
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}
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for(int i=0; i<remoteCatalog.size(); i++)
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{
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Vector v = (Vector)remoteCatalog.elementAt(i);
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//System.out.println("v2: " + v.toString());
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//System.out.println("i: " + i);
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//System.out.println("remoteCatalog.size(): " + remoteCatalog.size());
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//System.out.println("publicID: " + publicId.toString());
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//System.out.println("v.elementAt(3): " + (String)v.elementAt(3));
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if(!publicId.contains(v.elementAt(3)))
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{ //so we don't have this public id in our local table so we need to
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//add it.
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//System.out.println("in if");
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StringBuffer sql = new StringBuffer();
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sql.append("insert into xml_catalog (entry_type, source_doctype, ");
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sql.append("target_doctype, public_id, system_id) values (?,?,?,");
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sql.append("?,?)");
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//System.out.println("sql: " + sql.toString());
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PreparedStatement pstmt = conn.prepareStatement(sql.toString());
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pstmt.setString(1, (String)v.elementAt(0));
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pstmt.setString(2, (String)v.elementAt(1));
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pstmt.setString(3, (String)v.elementAt(2));
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pstmt.setString(4, (String)v.elementAt(3));
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pstmt.setString(5, (String)v.elementAt(4));
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pstmt.execute();
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}
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}
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}
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}
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catch(Exception e)
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{
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System.out.println("error in updateCatalog: " + e.getMessage());
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e.printStackTrace(System.out);
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}
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}
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/**
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* Method that returns true if docid has already been "deleted" from metacat.
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* This method really implements a truth table for deleted documents
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* The table is (a docid in one of the tables is represented by the X):
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* xml_docs xml_revs deleted?
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* ------------------------------------
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* X X FALSE
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* X _ FALSE
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* _ X TRUE
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* _ _ TRUE
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*/
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private static boolean alreadyDeleted(String docid, Connection conn)
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{
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try
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{
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boolean xml_docs = false;
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boolean xml_revs = false;
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StringBuffer sb = new StringBuffer();
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sb.append("select docid from xml_revisions where docid like '");
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sb.append(docid).append("'");
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PreparedStatement pstmt = conn.prepareStatement(sb.toString());
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pstmt.execute();
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ResultSet rs = pstmt.getResultSet();
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boolean tablehasrows = rs.next();
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if(tablehasrows)
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{
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xml_revs = true;
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}
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sb = new StringBuffer();
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sb.append("select docid from xml_documents where docid like '");
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sb.append(docid).append("'");
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pstmt = conn.prepareStatement(sb.toString());
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pstmt.execute();
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rs = pstmt.getResultSet();
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tablehasrows = rs.next();
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if(tablehasrows)
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{
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xml_docs = true;
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}
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if(xml_docs && xml_revs)
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{
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return false;
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}
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else if(xml_docs && !xml_revs)
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{
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return false;
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}
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else if(!xml_docs && xml_revs)
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{
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return true;
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}
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else if(!xml_docs && !xml_revs)
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{
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return true;
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}
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}
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catch(Exception e)
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{
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System.out.println("error in alreadyDeleted: " + e.getMessage());
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e.printStackTrace(System.out);
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}
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return false;
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}
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394
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/**
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* Checks to see if a document is already in the DB. Returns
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* "UPDATE" if it is, "INSERT" if it isn't
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*/
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399
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private static String getAction(String docid)
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400
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{
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401
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try
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402
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{
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403
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MetaCatUtil util = new MetaCatUtil();
|
404
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StringBuffer sql = new StringBuffer();
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sql.append("select docid from xml_documents where docid like '");
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sql.append(docid).append("'");
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Connection conn = util.openDBConnection();
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PreparedStatement pstmt = conn.prepareStatement(sql.toString());
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pstmt.execute();
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ResultSet rs = pstmt.getResultSet();
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if(rs.next())
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{
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conn.close();
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return "UPDATE";
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}
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else
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{
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conn.close();
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return "INSERT";
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}
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422
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}
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423
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catch(Exception e)
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424
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{
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425
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System.out.println("error in replicationHandler.getAction: " +
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426
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e.getMessage());
|
427
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}
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428
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return "";
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429
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}
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430
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|
431
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/**
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432
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* Method to query xml_replication and build a hashtable of each server
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433
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* and it's last update time.
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434
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* @param conn a connection to the database
|
435
|
*/
|
436
|
public static Hashtable buildServerList(Connection conn)
|
437
|
{
|
438
|
Hashtable sl = new Hashtable();
|
439
|
PreparedStatement pstmt;
|
440
|
try
|
441
|
{
|
442
|
pstmt = conn.prepareStatement("select server, last_checked from " +
|
443
|
"xml_replication");
|
444
|
pstmt.execute();
|
445
|
ResultSet rs = pstmt.getResultSet();
|
446
|
boolean tableHasRows = rs.next();
|
447
|
while(tableHasRows)
|
448
|
{
|
449
|
String server = rs.getString(1);
|
450
|
String last_checked = rs.getString(2);
|
451
|
if(!server.equals("localhost"))
|
452
|
{
|
453
|
sl.put(server, last_checked);
|
454
|
}
|
455
|
tableHasRows = rs.next();
|
456
|
}
|
457
|
}
|
458
|
catch(Exception e)
|
459
|
{
|
460
|
System.out.println("error in replicationHandler.buildServerList(): " +
|
461
|
e.getMessage());
|
462
|
}
|
463
|
return sl;
|
464
|
}
|
465
|
|
466
|
/**
|
467
|
* Method to initialize the message parser
|
468
|
*/
|
469
|
public static XMLReader initParser(DefaultHandler dh)
|
470
|
throws Exception
|
471
|
{
|
472
|
XMLReader parser = null;
|
473
|
|
474
|
try {
|
475
|
ContentHandler chandler = dh;
|
476
|
|
477
|
// Get an instance of the parser
|
478
|
MetaCatUtil util = new MetaCatUtil();
|
479
|
String parserName = util.getOption("saxparser");
|
480
|
parser = XMLReaderFactory.createXMLReader(parserName);
|
481
|
|
482
|
// Turn off validation
|
483
|
parser.setFeature("http://xml.org/sax/features/validation", false);
|
484
|
|
485
|
parser.setContentHandler((ContentHandler)chandler);
|
486
|
parser.setErrorHandler((ErrorHandler)chandler);
|
487
|
|
488
|
} catch (Exception e) {
|
489
|
throw e;
|
490
|
}
|
491
|
|
492
|
return parser;
|
493
|
}
|
494
|
}
|