Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that implements a metadata catalog as a java Servlet

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones, Dan Higgins, Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author: berkley $'

 *     '$Date: 2000-08-14 14:28:54 -0700 (Mon, 14 Aug 2000) $'

 * '$Revision: 351 $'

 */

package edu.ucsb.nceas.metacat;

import java.io.PrintWriter;

import java.io.IOException;

import java.io.Reader;

import java.io.StringReader;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.ResourceBundle; 

import java.util.PropertyResourceBundle;

import java.net.URL;

import java.net.MalformedURLException;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.Connection;

import java.sql.SQLException;

import javax.servlet.ServletConfig;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.ServletInputStream;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import javax.servlet.http.HttpUtils;

import oracle.xml.parser.v2.XSLStylesheet;

import oracle.xml.parser.v2.XSLException;

import oracle.xml.parser.v2.XMLDocumentFragment;

import oracle.xml.parser.v2.XSLProcessor;

import org.xml.sax.SAXException;

/**

 * A metadata catalog server implemented as a Java Servlet

 *

 * <p>Valid parameters are:<br>

 * action=query -- query the values of all elements and attributes

 *                     and return a result set of nodes<br>

 * action=squery -- structured query (see pathquery.dtd)<br>

 * action=insert -- insert an XML document into the database store<br>

 * action=update -- update an XML document that is in the database store<br>

 * action=delete --  delete an XML document from the database store<br>

 * action=validate -- vallidate the xml contained in valtext<br>

 * action=getdocument -- display an XML document in XML or HTML<br>

 * doctype -- document type list returned by the query (publicID)<br>

 * qformat=xml -- display resultset from query in XML<br>

 * qformat=html -- display resultset from query in HTML<br>

 * docid=34 -- display the document with the document ID number 34<br>

 * doctext -- XML text of the document to load into the database<br>

 * query -- actual query text (to go with 'action=query' or 'action=squery')<br>

 * valtext -- XML text to be validated<br>

 * action=getdatadoc -- retreive a stored datadocument<br>

 * action=getdoctypes -- retreive all doctypes (publicID)<br>

 * action=getdataguide -- retreive a Data Guide<br>

 * datadoc -- data document name (id)<br>

 * <p>

 * The particular combination of parameters that are valid for each 

 * particular action value is quite specific.  This documentation

 * will be reorganized to reflect this information.

 */

public class MetaCatServlet extends HttpServlet {

  private ServletConfig		config = null;

  private ServletContext	context = null;

  private Hashtable 		connectionPool = new Hashtable();

  private String 		resultStyleURL = null;

  private String 		xmlcatalogfile = null;

  private String 		saxparser = null;

  private String        defaultdatapath = null; 

					// path to directory where data files 

					// that can be downloaded will be stored

  private String        executescript  = null;  

					// script to get data file and put it 

                    // in defaultdocpath dir

  private PropertyResourceBundle options = null;

  private MetaCatUtil util = null;

  /**

   * Initialize the servlet by creating appropriate database connections

   */

  public void init( ServletConfig config ) throws ServletException {

    try {

      super.init( config );

      this.config = config;

      this.context = config.getServletContext(); 

      System.out.println("MetaCatServlet Initialize");

      util = new MetaCatUtil();

      // Get the configuration file information

      resultStyleURL = util.getOption("resultStyleURL");

      xmlcatalogfile = util.getOption("xmlcatalogfile");

      saxparser = util.getOption("saxparser");

      defaultdatapath = util.getOption("defaultdatapath");

      executescript = util.getOption("executescript");

      try {

        // Open a pool of db connections

        connectionPool = util.getConnectionPool();

      } catch (Exception e) {

        System.err.println("Error creating pool of database connections");

        System.err.println(e.getMessage());

      }

    } catch ( ServletException ex ) {

      throw ex;

    }

  }

  /**

   * Close all db connections from the pool

   */

  public void destroy() {

    if (util != null) {

        util.closeConnections();

    }

  }

  /** Handle "GET" method requests from HTTP clients */

  public void doGet (HttpServletRequest request, HttpServletResponse response)

    throws ServletException, IOException {

    // Process the data and send back the response

    handleGetOrPost(request, response);

  }

  /** Handle "POST" method requests from HTTP clients */

  public void doPost( HttpServletRequest request, HttpServletResponse response)

    throws ServletException, IOException {

    // Process the data and send back the response

    handleGetOrPost(request, response);

  }

  /**

   * Control servlet response depending on the action parameter specified

   */

  private void handleGetOrPost(HttpServletRequest request, 

    HttpServletResponse response) 

    throws ServletException, IOException {

    if ( util == null ) {

        util = new MetaCatUtil(); 

    }

    if ( connectionPool == null ) {

      try {

        // Open a pool of db connections

        connectionPool = util.getConnectionPool();

      } catch (Exception e) {

        System.err.println("Error creating pool of database connections");

        System.err.println(e.getMessage());

      }

    }    

    // Get a handle to the output stream back to the client

    PrintWriter out = response.getWriter();

    //response.setContentType("text/html");

    String name = null;

    String[] value = null;

    String[] docid = new String[3];

    Hashtable params = new Hashtable();

    Enumeration paramlist = request.getParameterNames();

    while (paramlist.hasMoreElements()) {

      name = (String)paramlist.nextElement();

      value = request.getParameterValues(name);

      // Decode the docid and mouse click information

      if (name.endsWith(".y")) {

        docid[0] = name.substring(0,name.length()-2);

        //out.println("docid => " + docid[0]);

        params.put("docid", docid);

        name = "ypos";

      }

      if (name.endsWith(".x")) {

        name = "xpos";

      }

      //out.println(name + " => " + value[0]);

      params.put(name,value);

    }

    // Determine what type of request the user made

    // if the action parameter is set, use it as a default

    // but if the ypos param is set, calculate the action needed

    String action = ((String[])params.get("action"))[0];

    long ypos = 0;

    try {

      ypos = (new Long(((String[])params.get("ypos"))[0]).longValue());

      //out.println("<P>YPOS IS " + ypos);

      if (ypos <= 13) {

        action = "getdocument";

      } else if (ypos > 13 && ypos <= 27) {

        action = "validate";

      } else if (ypos > 27) {

        action = "transform";

      //} else {

      //  action = "";

      }

    } catch (Exception npe) {

      //out.println("<P>Caught exception looking for Y value.");

    }

// Jivka added  

    // handle login action

    if (action.equals("Login") || action.equals("Login Client")) {

      handleLoginAction(out, params, request, response);

    // handle logout action  

    } else if (action.equals("Logout") || action.equals("Logout Client")) {

      HttpSession sess = request.getSession(false);

      if (sess != null) { sess.invalidate();  }    

      if (action.equals("Logout Client")) {

        out.println("<?xml version=\"1.0\"?>");

        out.println("<success>");

        out.println("User logout.");

        out.println("</success>");

        return;

      }    

      response.sendRedirect("/xmltodb/index.html"); 

    // aware of session expiration on every request  

    } else {   

      HttpSession sess = request.getSession(true);

      if (sess.isNew()) { 

        // session expired or has not been stored b/w user requests

        // redirect to default page for query only access

      //  response.sendRedirect("/xmltodb/sexpire.html");

      } 

    }    

// End of Jivka added

    if (action.equals("query") || action.equals("squery")) {

      handleQueryAction(out, params, response);

    } else if (action.equals("getdocument")) {

      try {

        handleGetDocumentAction(out, params, response);

      } catch (ClassNotFoundException e) {

        out.println(e.getMessage());

      } catch (SQLException se) {

        out.println(se.getMessage());

      }

    } else if (action.equals("insert") || action.equals("update")) {

      handleInsertOrUpdateAction(out, params, response);

    } else if (action.equals("delete")) {

      handleDeleteAction(out, params, response);

    } else if (action.equals("validate")) {

      handleValidateAction(out, params, response);  

    } else if (action.equals("getdatadoc")) {

      handleGetDataDocumentAction(out, params, response);  

    } else if (action.equals("getdoctypes")) {

      handleGetDoctypesAction(out, params, response);  

    } else if (action.equals("getdataguide")) {

      handleGetDataGuideAction(out, params, response);  

    } else if (action.equals("Login") || action.equals("Login Client")) {

    } else {

      out.println("Error: action not registered.  Please report this error.");

    }

    // Close the stream to the client

    out.close();

  }

// Jivka added

  /** 

   * Handle the Login request. Create a new session object.

   * Make a user authentication through SRB RMI Connection.

   */

  private void handleLoginAction(PrintWriter out, Hashtable params, 

               HttpServletRequest request, HttpServletResponse response) {

    MetaCatSession sess = null;

    String un = ((String[])params.get("username"))[0];

    String pw = ((String[])params.get("password"))[0];

    String action = ((String[])params.get("action"))[0];

    try {

        sess = new MetaCatSession(request, un, pw);

    } catch (Exception e) {

      out.println(e.getMessage());

    }

    if ( un.equals("anonymous") ) {

            try {

                if (action.equals("Login Client")) {

                    out.println("<?xml version=\"1.0\"?>");

                    out.println("<success>");

                    out.println("User Authentication successful.");

                    out.println("</success>");

                    return;

                } else {

                    response.sendRedirect(

                      response.encodeRedirectUrl("/berkley/index.html"));

                }    

            } catch ( java.io.IOException ioe) {

                sess.disconnect();            

                out.println("<?xml version=\"1.0\"?>");

                out.println("<error>");

                out.println("MetaCatServlet.handleLoginAction() - " +

                            "Error on redirect of HttpServletResponse: " + 

                            ioe.getMessage());

                out.println("</error>");

                return;

            }                

    }    

    try { 

        if (sess.userAuth(un, pw)) {

            try {

                if (action.equals("Login Client")) {

                    out.println("<?xml version=\"1.0\"?>");

                    out.println("<success>");

                    out.println("User Authentication successful.");

                    out.println("</success>");

                } else {

                    response.sendRedirect(

                    response.encodeRedirectUrl("/berkley/metacat.html"));

                }    

            } catch ( java.io.IOException ioe) {

                sess.disconnect();            

                out.println("<?xml version=\"1.0\"?>");

                out.println("<error>");

                out.println("MetaCatServlet.handleLoginAction() - " +

                            "Error on redirect of HttpServletResponse: " + 

                            ioe.getMessage());

                out.println("</error>");

            }                

        } else {  

            sess.disconnect();            

            out.println("<?xml version=\"1.0\"?>");

            out.println("<error>");

            out.println("SRB Connection failed. " +

                        "SRB RMI Server is not running now or " +

                        "user " + un + 

                        " has not been authenticated to use the system.");

            out.println("</error>");

        }    

    } catch ( java.rmi.RemoteException re) {

            sess.disconnect();            

            out.println("<?xml version=\"1.0\"?>");

            out.println("<error>");

            out.println("SRB Connection failed. " + re.getMessage());

            out.println("</error>"); 

    }        

  }

  /** 

    *Create the squery xml and return it as a String.

    * @param params is the Hashtable of parameters that should be included

    * in the squery.

    */

  private String handleSQuery(Hashtable params) 

  {

    //create the squery and return it to be processed

    String doctype = null;

    String[] doctypeArr = null;

    doctypeArr = (String[])params.get("doctype");

    doctype = null;

    if (doctypeArr != null) 

    {

      doctype = ((String[])params.get("doctype"))[0]; 

    }

    else

    {

      doctype="ANY"; 

    }

    return DBQuery.createSQuery(params, doctype);

  }

   /**

    *Create the query xml and return it as a String.

    * @param query is the free text query parameter returned through the CGI.

    * @param doctype is the doctype parameter returned through the CGI. 

    * If no doctype filter is required, set it to null or "".

    */

  private String handleQuery(Hashtable params)

  {

    String doctype=null; 

    String[] doctypeArr=null; 

    String query=null;

    if(params.containsKey("query"))

    {

      query = ((String[])params.get("query"))[0];

    }

    else

    {

      query = ""; 

    }

    if(params.containsKey("doctype"))

    {

      doctypeArr = (String[])params.get("doctype");

      doctype = null;

    }

    else

    {

      doctype = "ANY";  

    }

    if (doctypeArr != null) 

    {

      doctype = ((String[])params.get("doctype"))[0]; 

    }

    else

    {

      doctype="ANY"; 

    }

    return DBQuery.createQuery(query,doctype);

  }

  /**

    * Run the query and return a hashtable of results.

    */

  private Hashtable runQuery(StringBuffer xmlquery)

  {

    Hashtable doclist=null;

    Connection conn = null;

    try

    {

        conn = util.getConnection();

        DBQuery queryobj = new DBQuery(conn, saxparser);

        doclist = queryobj.findDocuments(new StringReader(xmlquery.toString()));

        util.returnConnection(conn);

        return doclist;

    } 

    catch (Exception e) 

    {

      if (conn != null) 

      {

        util.returnConnection(conn); 

      }

      util.debugMessage("Error in runQuery: " + e.getMessage());

      doclist = null;

      return doclist;

    }    

  }

  private void transformDocument(Hashtable doclist, String qformat, 

                                 String xmlquery, PrintWriter out,

                                 HttpServletResponse response)

  {

    // Create a buffer to hold the xml result

    StringBuffer resultset = new StringBuffer();

    // Print the resulting root nodes

    String docid = null;

    String document = null;

    resultset.append("<?xml version=\"1.0\"?>\n");

    resultset.append("<resultset>\n");

    //resultset.append("  <query>" + xmlquery + "</query>");   

    Enumeration doclistkeys = doclist.keys(); 

    while (doclistkeys.hasMoreElements()) 

    {

      docid = (String)doclistkeys.nextElement();

      document = (String)doclist.get(docid);

      resultset.append("  <document>" + document + "</document>");

    }

    resultset.append("</resultset>");

    if(qformat.equals("xml")) 

    {

      // set content type and other response header fields first

      response.setContentType("text/xml");

      out.println(resultset.toString());

    } 

    else if(qformat.equals("html")) 

    {

      // set content type and other response header fields first

      response.setContentType("text/html");

      XMLDocumentFragment htmldoc = null;

      try 

      {

        XSLStylesheet style = new XSLStylesheet(

                              new URL(resultStyleURL), null);

        htmldoc = (new XSLProcessor()).processXSL(style, 

                  (Reader)(new StringReader(resultset.toString())),null);

        htmldoc.print(out);

      } 

      catch (Exception e)   

      {

        out.println("Error transforming document:\n" + e.getMessage());

      }

    }

  }

  /** 

   * Handle the database query request and return a result set, possibly

   * transformed from XML into HTML

   */ 

  private void handleQueryAction(PrintWriter out, Hashtable params, 

                                 HttpServletResponse response)  

  {

      String action = ((String[])params.get("action"))[0];

      Hashtable doclist = null;

      String[] doctypeArr = null;

      String doctype = null;

      StringBuffer xmlquery = null;

      Connection conn = null;

      if(action.equals("query"))

      {

        xmlquery = new StringBuffer(handleQuery(params));

      }

      else if(action.equals("squery"))

      {

        xmlquery = new StringBuffer(handleSQuery(params));

      }

      //System.out.println("Query is: ");

      //System.out.println(xmlquery.toString());

      doclist = runQuery(xmlquery);

      //System.out.println("result is: " );

      //System.out.println(doclist.toString());

      String qformat = ((String[])params.get("qformat"))[0]; 

      transformDocument(doclist, qformat, xmlquery.toString(), out, response);

  }

  /** 

   * Handle the database getdocument request and return a XML document, 

   * possibly transformed from XML into HTML

   */

  private void handleGetDocumentAction(PrintWriter out, Hashtable params, 

               HttpServletResponse response) 

               throws ClassNotFoundException, IOException, SQLException {

    String docidstr = null;

    String docid = null;

    String doc = null;

    Connection conn = null;

    try {

      // Find the document id number

      docidstr = ((String[])params.get("docid"))[0]; 

      //docid = (new Long(docidstr)).longValue();

      docid = docidstr;

      conn = util.getConnection();

      DBReader docreader = new DBReader(conn);

      DBTransform dbt = new DBTransform(conn);

      // Get the document indicated fromthe db

      doc = docreader.readXMLDocument(docid);

      // Return the document in XML or HTML format

      String qformat = ((String[])params.get("qformat"))[0]; 

      if (qformat.equals("xml")) {

        // set content type and other response header fields first

        response.setContentType("text/xml");

        out.println(doc);

      } else if (qformat.equals("html")) {

        // set content type and other response header fields first

        response.setContentType("text/html");

        // Look up the document type

        String sourcetype = docreader.getDoctypeInfo(docid).getDoctype();

        // Transform the document to the new doctype

        dbt.transformXMLDocument(doc, sourcetype, "-//W3C//HTML//EN", out);

      }

    //} catch (NullPointerException npe) {

      //response.setContentType("text/html");

      //out.println("Error getting document ID: " + docidstr +" (" + docid + ")");

    } catch (McdbException e) {

      response.setContentType("text/xml");

      e.toXml(out);

    } catch (Throwable t) {

      response.setContentType("text/html");

      out.println(t.getMessage());

    } finally {

      util.returnConnection(conn);

    }    

  }

  /** 

   * Handle the database putdocument request and write an XML document 

   * to the database connection

   */

  private void handleInsertOrUpdateAction(PrintWriter out, Hashtable params, 

               HttpServletResponse response) {

    Connection conn = null;

    try {

      // Get the document indicated

      String[] doctext = (String[])params.get("doctext");

      StringReader xml = null;

      try {

        xml = new StringReader(doctext[0]);

        String[] action = (String[])params.get("action");

        String[] docid = (String[])params.get("docid");

        String newdocid = null;

        String doAction = null;

        if (action[0].equals("insert")) {

          doAction = "INSERT";

        } else if (action[0].equals("update")) {

          doAction = "UPDATE";

        }

        try {

            // get a connection from the pool

            conn = util.getConnection();

            // write the document to the database

            DBWriter dbw = new DBWriter(conn, saxparser);

            try {

                String accNumber = docid[0];

                if (accNumber.equals("")) {

                    accNumber = null;

                }

                newdocid = dbw.write(xml, doAction, accNumber);  

            } catch (NullPointerException npe) {

              newdocid = dbw.write(xml, doAction, null);  

            }

        } catch (Exception e) {

          response.setContentType("text/html");

          out.println(e.getMessage());

        } finally {

          util.returnConnection(conn);

        }    

        // set content type and other response header fields first

        response.setContentType("text/xml");

        out.println("<?xml version=\"1.0\"?>");

        out.println("<success>");

        out.println("<docid>" + newdocid + "</docid>"); 

        out.println("</success>");

      } catch (NullPointerException npe) {

        response.setContentType("text/xml");

        out.println("<?xml version=\"1.0\"?>");

        out.println("<error>");

        out.println(npe.getMessage()); 

        out.println("</error>");

      }

    } catch (Exception e) {

      response.setContentType("text/xml");

      out.println("<?xml version=\"1.0\"?>");

      out.println("<error>");

      out.println(e.getMessage()); 

      if (e instanceof SAXException) {

        Exception e2 = ((SAXException)e).getException();

        out.println("<error>");

        out.println(e2.getMessage()); 

        out.println("</error>");

      }

      //e.printStackTrace(out);

      out.println("</error>");

    }

  }

  /** 

   * Handle the database delete request and delete an XML document 

   * from the database connection

   */

  private void handleDeleteAction(PrintWriter out, Hashtable params, 

               HttpServletResponse response) {

    String[] docid = (String[])params.get("docid");

    Connection conn = null;

    // delete the document from the database

    try {

      // get a connection from the pool

      conn = util.getConnection();

      DBWriter dbw = new DBWriter(conn, saxparser);

                                      // NOTE -- NEED TO TEST HERE

                                      // FOR EXISTENCE OF PARAM

                                      // BEFORE ACCESSING ARRAY

      try {

        dbw.delete(docid[0]);

        response.setContentType("text/xml");

        out.println("<?xml version=\"1.0\"?>");

        out.println("<success>");

        out.println("Document deleted."); 

        out.println("</success>");

      } catch (AccessionNumberException ane) {

        response.setContentType("text/xml");

        out.println("<?xml version=\"1.0\"?>");

        out.println("<error>");

        out.println("Error deleting document!!!");

        out.println(ane.getMessage()); 

        out.println("</error>");

      }

    } catch (Exception e) {

      response.setContentType("text/xml");

      out.println("<?xml version=\"1.0\"?>");

      out.println("<error>");

      out.println(e.getMessage()); 

      out.println("</error>");

    } finally {

      util.returnConnection(conn);

    }  

  }

  /** 

   * Handle the validtion request and return the results to the requestor

   */

  private void handleValidateAction(PrintWriter out, Hashtable params, 

               HttpServletResponse response) {

    // Get the document indicated

    String valtext = null;

    try {

      valtext = ((String[])params.get("valtext"))[0];

    } catch (Exception nullpe) {

      Connection conn = null;

      String docid = null;

      try {

        // Find the document id number

        docid = ((String[])params.get("docid"))[0]; 

        // get a connection from the pool

        conn = util.getConnection();

        DBReader docreader = new DBReader(conn);

        // Get the document indicated from the db

        valtext = docreader.readXMLDocument(docid);

      } catch (NullPointerException npe) {

        response.setContentType("text/xml");

        out.println("<error>Error getting document ID: " + docid + "</error>");

        if ( conn != null ) { util.returnConnection(conn); }

        return; // Jivka added

      } catch (Exception e) {

        response.setContentType("text/html");

        out.println(e.getMessage()); 

      } finally {

        util.returnConnection(conn);

      }  

    }

    Connection conn = null;

    try {

      // get a connection from the pool

      conn = util.getConnection();

      DBValidate valobj = new DBValidate(saxparser,conn);

      boolean valid = valobj.validateString(valtext);

      // set content type and other response header fields first

      response.setContentType("text/xml");

      out.println(valobj.returnErrors());

    } catch (NullPointerException npe2) {

      // set content type and other response header fields first

      response.setContentType("text/xml");

      out.println("<error>Error validating document.</error>"); 

    } catch (Exception e) {

      response.setContentType("text/html");

      out.println(e.getMessage()); 

    } finally {

      util.returnConnection(conn);

    }  

  }

  /** 

   * Handle the document request and return the results 

   * to the requestor

   */

  private void handleGetDataDocumentAction(PrintWriter out, Hashtable params, 

               HttpServletResponse response) {

      boolean error_flag = false;

      String error_message = "";

      // Get the document indicated

      String[] datadoc = (String[])params.get("datadoc");

      // defaultdatapath = "C:\\Temp\\";    // for testing only!!!

      // executescript = "test.bat";        // for testing only!!!

      // set content type and other response header fields first

      response.setContentType("application/octet-stream");

      if (defaultdatapath!=null) {

        if(!defaultdatapath.endsWith(System.getProperty("file.separator"))) {

          defaultdatapath=defaultdatapath+System.getProperty("file.separator");

        }

        System.out.println("Path= "+defaultdatapath+datadoc[0]);

        if (executescript!=null) {

          String command = null;

          File scriptfile = new File(executescript);

          if (scriptfile.exists()) {

            command=executescript+" "+datadoc[0]; // script includes path

        } else {     // look in defaultdatapath

            // on Win98 one MUST include the .bat extender

            command = defaultdatapath+executescript+" "+datadoc[0];  

        }

      System.out.println(command);

      try {

      Process proc = Runtime.getRuntime().exec(command);

      proc.waitFor();

      }

      catch (Exception eee) {

        System.out.println("Error running process!");

        error_flag = true;

        error_message = "Error running process!";}

      } // end executescript not null if

      File datafile = new File(defaultdatapath+datadoc[0]);

      try {

      FileInputStream fw = new FileInputStream(datafile);

      int x;

      while ((x = fw.read())!=-1) {

        out.write(x); }

        fw.close();

      } catch (Exception e) {

        System.out.println("Error in returning file\n"+e.getMessage());

        error_flag=true;

        error_message = error_message+"\nError in returning file\n"+

                        e.getMessage();

      }

    } // end defaultdatapath not null if

  }

  /** 

   * Handle the getdoctypes Action.

   * Read all doctypes from db connection in XML format

   */

  private void handleGetDoctypesAction(PrintWriter out, Hashtable params, 

                                       HttpServletResponse response) {

    Connection conn = null;

    try {

        // get connection from the pool

        conn = util.getConnection();

        DBUtil dbutil = new DBUtil(conn);

        String doctypes = dbutil.readDoctypes();

        out.println(doctypes);

    } catch (Exception e) {

      out.println("<?xml version=\"1.0\"?>");

      out.println("<error>");

      out.println(e.getMessage());

      out.println("</error>");

    } finally {

      util.returnConnection(conn);

    }