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, Chad Berkley

 *    Release: @release@

 *

 *   '$Author: tao $'

 *     '$Date: 2003-03-03 18:05:55 -0800 (Mon, 03 Mar 2003) $'

 * '$Revision: 1444 $'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

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

 */

package edu.ucsb.nceas.metacat;

import com.oreilly.servlet.multipart.FilePart;

import com.oreilly.servlet.multipart.MultipartParser;

import com.oreilly.servlet.multipart.ParamPart;

import com.oreilly.servlet.multipart.Part;

import java.io.File;

import java.io.PrintWriter;

import java.io.IOException;

import java.io.StringReader;

import java.io.FileInputStream;

import java.io.BufferedInputStream;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.ResourceBundle;

import java.util.Random;

import java.util.PropertyResourceBundle;

import java.util.Vector;

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 java.lang.reflect.*;

import java.net.*;

import java.util.zip.*;

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 javax.servlet.ServletOutputStream;

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= -- export a zip format for data packadge<br>

 * action=read -- read any metadata/data file from Metacat and from Internet<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>

 * 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>

 * qformat=zip -- zip resultset from query<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>

 * acltext -- XML access text for a document to load into the database<br>

 * dtdtext -- XML DTD text for a new DTD to load into Metacat XML Catalog<br>

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

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

 * abstractpath -- XPath in metadata document to read from<br>

 * action=getaccesscontrol -- retrieve acl info for Metacat document<br>

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

 * action=getdtdschema -- retrieve a DTD or Schema file<br>

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

 * action=getprincipals -- retrieve a list of principals in XML<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 String resultStyleURL = null;

  private String xmlcatalogfile = null;

  private String saxparser = null;

  private String datafilepath = null;

  private File dataDirectory = null;

  private String servletpath = null;

  private String htmlpath = null;

  private PropertyResourceBundle options = null;

  private MetaCatUtil util = null;

  private DBConnectionPool connPool = null;

  private static final String PROLOG = "<?xml version=\"1.0\"?>";

  private static final String SUCCESS = "<success>";

  private static final String SUCCESSCLOSE = "</success>";

  private static final String ERROR = "<error>";

  private static final String ERRORCLOSE = "</error>";

  public static final String SCHEMALOCATIONKEYWORD = "xsi:schemaLocation";

  public static final String EML2KEYWORD ="<eml:eml";

  /**

   * 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();

      //initial DBConnection pool

      connPool = DBConnectionPool.getInstance();

      // Get the configuration file information

      resultStyleURL = util.getOption("resultStyleURL");

      xmlcatalogfile = util.getOption("xmlcatalogfile");

      saxparser = util.getOption("saxparser");

      datafilepath = util.getOption("datafilepath");

      dataDirectory = new File(datafilepath);

      servletpath = util.getOption("servletpath");

      htmlpath = util.getOption("htmlpath");

    } catch ( ServletException ex ) {

      throw ex;

    } catch (SQLException e) {

      MetaCatUtil.debugMessage("Error in MetacatServlet.init: "

                                          +e.getMessage(), 20);

    }

  }

  /**

   * Close all db connections from the pool

   */

  public void destroy() {

      // Close all db connection

      System.out.println("Destroying MetacatServlet");

      connPool.release();

  }

  /** 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();

    }

    /*MetaCatUtil.debugMessage("Connection pool size: "

                                     +connPool.getSizeOfDBConnectionPool(),10);

    MetaCatUtil.debugMessage("Free DBConnection number: "

                                  +connPool.getFreeDBConnectionNumber(), 10);*/

    //If all DBConnection in the pool are free and DBConnection pool

    //size is greater than initial value, shrink the connection pool

    //size to initial value

    DBConnectionPool.shrinkDBConnectionPoolSize();

    //Debug message to print out the method which have a busy DBConnection

    connPool.printMethodNameHavingBusyDBConnection();

    String ctype = request.getContentType();

    if (ctype != null && ctype.startsWith("multipart/form-data")) {

      handleMultipartForm(request, response);

    } else {

      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);

          params.put("docid", docid);

          name = "ypos";

        }

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

          name = "xpos";

        }

        params.put(name,value);

      }

      //handle param is emptpy

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

      {

        return;

      }

      //if the user clicked on the input images, decode which image

      //was clicked then set the action.

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

      util.debugMessage("Line 230: Action is: " + action, 1);

      // This block handles session management for the servlet

      // by looking up the current session information for all actions

      // other than "login" and "logout"

      String username = null;

      String password = null;

      String[] groupnames = null;

      String sess_id = null;

      // handle login action

      if (action.equals("login")) {

        PrintWriter out = response.getWriter();

        handleLoginAction(out, params, request, response);

        out.close();

      // handle logout action

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

        PrintWriter out = response.getWriter();

        handleLogoutAction(out, params, request, response);

        out.close();

      // handle shrink DBConnection request

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

        PrintWriter out = response.getWriter();

        boolean success = false;

        //If all DBConnection in the pool are free and DBConnection pool

        //size is greater than initial value, shrink the connection pool

        //size to initial value

        success = DBConnectionPool.shrinkConnectionPoolSize();

        if (success)

        {

          //if successfully shrink the pool size to initial value

          out.println("DBConnection Pool shrink successfully");

        }//if

        else

        {

          out.println("DBConnection pool couldn't shrink successfully");

        }

       //close out put

        out.close();

      // 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

          username = "public";

          sess.setAttribute("username", username);

        } else {

          username = (String)sess.getAttribute("username");

          password = (String)sess.getAttribute("password");

          groupnames = (String[])sess.getAttribute("groupnames");

          try {

            sess_id = (String)sess.getId();

          } catch(IllegalStateException ise) {

            System.out.println("error in handleGetOrPost: this shouldn't " +

                               "happen: the session should be valid: " +

                               ise.getMessage());

          }

        }

      }

       // Now that we know the session is valid, we can delegate the request

      // to a particular action handler

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

        PrintWriter out = response.getWriter();

        handleQuery(out,params,response,username,groupnames);

        out.close();

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

        PrintWriter out = response.getWriter();

        if(params.containsKey("query")) {

         handleSQuery(out, params,response,username,groupnames);

         out.close();

        } else {

          out.println("Illegal action squery without \"query\" parameter");

          out.close();

        }

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

        handleExportAction(params, response, username, groupnames, password);

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

        handleReadAction(params, response, username,password, groupnames);

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

        PrintWriter out = response.getWriter();

        if ( (username != null) &&  !username.equals("public") ) {

          handleInsertOrUpdateAction(out,params,username,groupnames);

        } else {

          out.println("Permission denied for user"+username +" " + action);

        }

        out.close();

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

        PrintWriter out = response.getWriter();

        if ( (username != null) &&  !username.equals("public") ) {

          handleDeleteAction(out, params, response, username, groupnames);

        } else {

          out.println("Permission denied for " + action);

        }

        out.close();

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

        PrintWriter out = response.getWriter();

        handleValidateAction(out, params);

        out.close();

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

         PrintWriter out = response.getWriter();

         handleSetAccessAction(out, params, username);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetAccessControlAction(out,params,response,username,groupnames);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetPrincipalsAction(out, username, password);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetDoctypesAction(out, params, response);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetDTDSchemaAction(out, params, response);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetDataGuideAction(out, params, response);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetMaxDocidAction(out, params, response);

        out.close();

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

        PrintWriter out = response.getWriter();

        handleGetRevisionAndDocTypeAction(out, params);

        out.close();

      } else if (action.equals("login") || action.equals("logout")) {

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

        String testURL = "metacat://dev.nceas.ucsb.edu/NCEAS.897766.9";

        try {

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

        } catch (Throwable t) {

        }

        String phandler = System.getProperty("java.protocol.handler.pkgs");

        response.setContentType("text/html");

        PrintWriter out = response.getWriter();

        out.println("<body bgcolor=\"white\">");

        out.println("<p>Handler property: <code>" + phandler + "</code></p>");

        out.println("<p>Starting test for:<br>");

        out.println("    " + testURL + "</p>");

        try {

          URL u = new URL(testURL);

          out.println("<pre>");

          out.println("Protocol: " + u.getProtocol());

          out.println("    Host: " + u.getHost());

          out.println("    Port: " + u.getPort());

          out.println("    Path: " + u.getPath());

          out.println("     Ref: " + u.getRef());

          String pquery = u.getQuery();

          out.println("   Query: " + pquery);

          out.println("  Params: ");

          if (pquery != null) {

            Hashtable qparams = util.parseQuery(u.getQuery());

            for (Enumeration en = qparams.keys(); en.hasMoreElements(); ) {

              String pname = (String)en.nextElement();

              String pvalue = (String)qparams.get(pname);

              out.println("    " + pname + ": " + pvalue);

            }

          }

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

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

          out.close();

        } catch (MalformedURLException mue) {

          System.out.println("bad url from MetacatServlet.handleGetOrPost");

          out.println(mue.getMessage());

          mue.printStackTrace(out);

          out.close();

        }

      } else {

        PrintWriter out = response.getWriter();

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

        out.println("<error>");

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

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

        out.close();

      }

      //util.closeConnections();

      // Close the stream to the client

      //out.close();

    }

  }

  // LOGIN & LOGOUT SECTION

  /**

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

   * Do user authentication through the session.

   */

  private void handleLoginAction(PrintWriter out, Hashtable params,

               HttpServletRequest request, HttpServletResponse response) {

    AuthSession sess = null;

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

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

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

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

    try {

      sess = new AuthSession();

    } catch (Exception e) {

      System.out.println("error in MetacatServlet.handleLoginAction: " +

                          e.getMessage());

      out.println(e.getMessage());

      return;

    }

    boolean isValid = sess.authenticate(request, un, pw);

    // format and transform the output

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

      response.setContentType("text/xml");

      out.println(sess.getMessage());

    } else {

      try {

        DBTransform trans = new DBTransform();

        response.setContentType("text/html");

        trans.transformXMLDocument(sess.getMessage(), "-//NCEAS//login//EN",

                                   "-//W3C//HTML//EN", qformat, out);

      } catch(Exception e) {

        MetaCatUtil.debugMessage("Error in MetaCatServlet.handleLoginAction: "

                                +e.getMessage(), 30);

      }

    // any output is returned

    }

  }

  /**

   * Handle the logout request. Close the connection.

   */

  private void handleLogoutAction(PrintWriter out, Hashtable params,

               HttpServletRequest request, HttpServletResponse response) {

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

    // close the connection

    HttpSession sess = request.getSession(false);

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

    // produce output

    StringBuffer output = new StringBuffer();

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

    output.append("<logout>");

    output.append("User logged out");

    output.append("</logout>");

    //format and transform the output

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

      response.setContentType("text/xml");

      out.println(output.toString());

    } else {

      try {

        DBTransform trans = new DBTransform();

        response.setContentType("text/html");

        trans.transformXMLDocument(output.toString(), "-//NCEAS//login//EN",

                                   "-//W3C//HTML//EN", qformat, out);

      } catch(Exception e) {

        MetaCatUtil.debugMessage("Error in MetaCatServlet.handleLogoutAction"

                                  +e.getMessage(), 30);

      }

    }

  }

  // END OF LOGIN & LOGOUT SECTION

  // SQUERY & QUERY SECTION

  /**

   * Retreive the squery xml, execute it and display it

   *

   * @param out the output stream to the client

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

   * in the squery.

   * @param response the response object linked to the client

   * @param conn the database connection

   */

  protected void handleSQuery(PrintWriter out, Hashtable params,

                 HttpServletResponse response, String user, String[] groups)

  {

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

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

    String resultdoc = null;

    MetaCatUtil.debugMessage("xmlquery: "+xmlquery, 30);

    double startTime = System.currentTimeMillis()/1000;

    Hashtable doclist = runQuery(xmlquery, user, groups);

    double docListTime = System.currentTimeMillis()/1000;

    MetaCatUtil.debugMessage("Time for getting doc list: "

                                            +(docListTime-startTime), 30);

    resultdoc = createResultDocument(doclist, transformQuery(xmlquery));

    double toStringTime = System.currentTimeMillis()/1000;

    MetaCatUtil.debugMessage("Time to create xml string: "

                              +(toStringTime-docListTime), 30);

    //format and transform the results

    double outPutTime = 0;

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

      response.setContentType("text/xml");

      out.println(resultdoc);

      outPutTime = System.currentTimeMillis()/1000;

      MetaCatUtil.debugMessage("Output time: "+(outPutTime-toStringTime), 30);

    } else {

      transformResultset(resultdoc, response, out, qformat);

      outPutTime = System.currentTimeMillis()/1000;

      MetaCatUtil.debugMessage("Output time: "+(outPutTime-toStringTime), 30);

    }

  }

   /**

    * Create the xml query, execute it and display the results.

    *

    * @param out the output stream to the client

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

    * in the squery.

    * @param response the response object linked to the client

    */

  protected void handleQuery(PrintWriter out, Hashtable params,

                 HttpServletResponse response, String user, String[] groups)

  {

    //create the query and run it

    String xmlquery = DBQuery.createSQuery(params);

    Hashtable doclist = runQuery(xmlquery, user, groups);

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

    String resultdoc = null;

    resultdoc = createResultDocument(doclist, transformQuery(params));

    //format and transform the results

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

      response.setContentType("text/xml");

      out.println(resultdoc);

    } else {

      transformResultset(resultdoc, response, out, qformat);

    }

  }

  /**

   * Removes the <?xml version="x"?> tag from the beginning of xmlquery

   * so it can properly be placed in the <query> tag of the resultset.

   * This method is overwritable so that other applications can customize

   * the structure of what is in the <query> tag.

   *

   * @param xmlquery is the query to remove the <?xml version="x"?> tag from.

   */

  protected String transformQuery(Hashtable params)

  {

    //DBQuery.createSQuery is a re-calling of a previously called

    //function but it is necessary

    //so that overriding methods have access to the params hashtable

    String xmlquery = DBQuery.createSQuery(params);

    //the <?xml version="1.0"?> tag is the first 22 characters of the

    xmlquery = xmlquery.trim();

    int index = xmlquery.indexOf("?>");

    return xmlquery.substring(index + 2, xmlquery.length());

  }

  /**

   * removes the <?xml version="1.0"?> tag from the beginning.  This takes a

   * string as a param instead of a hashtable.

   *

   * @param xmlquery a string representing a query.

   */

  protected String transformQuery(String xmlquery)

  {

    xmlquery = xmlquery.trim();

    int index = xmlquery.indexOf("?>");

    return xmlquery.substring(index + 2, xmlquery.length());

  }

  /**

   * Run the query and return a hashtable of results.

   *

   * @param xmlquery the query to run

   */

  private Hashtable runQuery(String xmlquery, String user, String[] groups)

  {

    Hashtable doclist=null;

    try

    {

      DBQuery queryobj = new DBQuery(saxparser);

      doclist = queryobj.findDocuments(new StringReader(xmlquery),user,groups);

      return doclist;

    }

    catch (Exception e)

    {

      MetaCatUtil.debugMessage("Error in MetacatServlet.runQuery: "

                                                      + e.getMessage(), 30);

      doclist = null;

      return doclist;

    }

  }

  /**

   * Transorms an xml resultset document to html and sends it to the browser

   *

   * @param resultdoc the string representation of the document that needs

   * to be transformed.

   * @param response the HttpServletResponse object bound to the client.

   * @param out the output stream to the client

   * @param qformat the name of the style-set to use for transformations

   */

  protected void transformResultset(String resultdoc,

                                    HttpServletResponse response,

                                    PrintWriter out, String qformat)

  {

    try {

      DBTransform trans = new DBTransform();

      response.setContentType("text/html");

      trans.transformXMLDocument(resultdoc, "-//NCEAS//resultset//EN",

                                 "-//W3C//HTML//EN", qformat, out);

    }

    catch(Exception e)

    {

      MetaCatUtil.debugMessage("Error in MetaCatServlet.transformResultset:"

                                +e.getMessage(), 30);

    }

  }

  /**

   * Transforms a hashtable of documents to an xml or html result.

   *

   * @param doclist- the hashtable to transform

   * @param xmlquery- the query that returned the doclist result

   */

  protected String createResultDocument(Hashtable doclist, String xmlquery)

  {

    // 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>");

    if(doclist != null)

    {

      Enumeration doclistkeys = doclist.keys();

      while (doclistkeys.hasMoreElements())

      {

        docid = (String)doclistkeys.nextElement();

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

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

      }

    }

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

    return resultset.toString();

  }

  // END OF SQUERY & QUERY SECTION

 //Exoport section

 /**

   * Handle the "export" request of data package from Metacat in zip format

   * @param params the Hashtable of HTTP request parameters

   * @param response the HTTP response object linked to the client

   * @param user the username sent the request

   * @param groups the user's groupnames

   */

  private void handleExportAction(Hashtable params,

    HttpServletResponse response, String user, String[] groups, String passWord)

  {

    // Output stream

    ServletOutputStream out = null;

    // Zip output stream

    ZipOutputStream zOut = null;

    DocumentImpl docImpls=null;

    DBQuery queryObj=null;

    String[] docs = new String[10];

    String docId = "";

    try

    {

      // read the params

      if (params.containsKey("docid"))

      {

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

      }//if

      // Create a DBuery to handle export

      queryObj = new DBQuery(saxparser);

      // Get the docid

      docId=docs[0];

      // Make sure the client specify docid

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

      {

        response.setContentType("text/xml"); //MIME type

        // Get a printwriter

        PrintWriter pw = response.getWriter();

        // Send back message

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

        pw.println("<error>");

        pw.println("You didn't specify requested docid");

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

        // Close printwriter

        pw.close();

        return;

      }//if

      // Get output stream

      out = response.getOutputStream();

      response.setContentType("application/zip"); //MIME type

      zOut = new ZipOutputStream(out);

      zOut =queryObj.getZippedPackage(docId, out, user, groups, passWord);

      zOut.finish(); //terminate the zip file

      zOut.close();  //close the zip stream

    }//try

    catch (Exception e)

    {

      try

      {

        response.setContentType("text/xml"); //MIME type

        // Send error message back

        if (out != null)

        {

            PrintWriter pw = new PrintWriter(out);

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

            pw.println("<error>");

            pw.println(e.getMessage());

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

            // Close printwriter

            pw.close();

            // Close output stream

            out.close();

        }//if

        // Close zip output stream

        if ( zOut != null )

        {

          zOut.close();

        }//if

      }//try

      catch (IOException ioe)

      {

        MetaCatUtil.debugMessage("Problem with the servlet output " +

                           "in MetacatServlet.handleExportAction: " +

                           ioe.getMessage(), 30);

      }//catch

      MetaCatUtil.debugMessage("Error in MetacatServlet.handleExportAction: " +

                         e.getMessage(), 30);

      e.printStackTrace(System.out);

    }//catch

  }//handleExportAction

  // READ SECTION

  /**

   * Handle the "read" request of metadata/data files from Metacat

   * or any files from Internet;

   * transformed metadata XML document into HTML presentation if requested;

   * zip files when more than one were requested.

   *

   * @param params the Hashtable of HTTP request parameters

   * @param response the HTTP response object linked to the client

   * @param user the username sent the request

   * @param groups the user's groupnames

   */

  private void handleReadAction(Hashtable params, HttpServletResponse response,

                                String user, String passWord, String[] groups)

  {

    ServletOutputStream out = null;

    ZipOutputStream zout = null;

    PrintWriter pw = null;

    boolean zip = false;

    try {

      String[] docs = new String[0];

      String docid = "";

      String qformat = "";

      String abstrpath = null;

      // read the params

      if (params.containsKey("docid")) {

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

      }

      if (params.containsKey("qformat")) {

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

      }

      if (params.containsKey("abstractpath")) {

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

        if ( !abstrpath.equals("") && (abstrpath != null) ) {

          viewAbstract(response, abstrpath, docs[0]);

          return;

        }

      }

      if ( (docs.length > 1) || qformat.equals("zip") ) {

        zip = true;

        out = response.getOutputStream();

        response.setContentType("application/zip"); //MIME type

        zout = new ZipOutputStream(out);