Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that handles the SAX XML events as they

 *             are generated from XML documents

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones, Jivka Bojilova

 *    Release: @release@

 *

 *   '$Author$'

 *     '$Date$'

 * '$Revision$'

 *

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

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

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

 * (at your option) any later version.

 *

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

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

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

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

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

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

 */

package edu.ucsb.nceas.metacat;

import java.sql.*;

import java.io.StringReader;

import java.util.Stack;

import java.util.Vector;

import java.util.Hashtable;

import java.util.Enumeration;

import java.util.EmptyStackException;

import org.xml.sax.Attributes;

import org.xml.sax.SAXException;

import org.xml.sax.SAXParseException;

import org.xml.sax.ext.DeclHandler;

import org.xml.sax.ext.LexicalHandler;

import org.xml.sax.helpers.DefaultHandler;

/**

 * A database aware Class implementing callback bethods for the SAX parser to

 * call when processing the XML stream and generating events

 */

public class EmlSAXHandler extends DBSAXHandler implements 

                                                      AccessControlInterface

{

   private Vector allowRules = new Vector();

   private Vector denyRules = new Vector();

   private String documentId = null;

   private Vector subDocumentIdList = new Vector();

   // Constant

   private static final String DESCRIBES = "describes";

    /** Construct an instance of the handler class

    *

    * @param conn the JDBC connection to which information is written

    * @param action - "INSERT" or "UPDATE"

    * @param docid to be inserted or updated into JDBC connection

    * @param user the user connected to MetaCat servlet and owns the document

    * @param groups the groups to which user belongs

    * @param pub flag for public "read" access on document

    * @param serverCode the serverid from xml_replication on which this document

    *        resides.

    *

    */

   public EmlSAXHandler(DBConnection conn, String action, String docid,

                      String user, String[] groups, String pub, int serverCode)

   {

     super(conn, action, docid, user, groups, pub, serverCode);

   }

   /** SAX Handler that is called at the start of each XML element */

   public void startElement(String uri, String localName,

                            String qName, Attributes atts)

               throws SAXException 

  {

      // for element <eml:eml...> qname is "eml:eml", local name is "eml"            

     // for element <acl....> both qname and local name is "eml"

     // uri is namesapce

     MetaCatUtil.debugMessage("Start ELEMENT(qName) " + qName, 50);

     MetaCatUtil.debugMessage("Start ELEMENT(localName) " + localName, 50);

     MetaCatUtil.debugMessage("Start ELEMENT(uri) " + uri, 50);

     DBSAXNode parentNode = null;

     DBSAXNode currentNode = null;

     // Get a reference to the parent node for the id

     try {

       parentNode = (DBSAXNode)nodeStack.peek();

     } catch (EmptyStackException e) {

       parentNode = null;

     }

     // Document representation that points to the root document node

     if (atFirstElement) 

     {

       atFirstElement = false;

       // If no DOCTYPE declaration: docname = root element

       // doctype = root element name or name space

       if (docname == null) 

       {

         docname = localName;

         // if uri isn't null doctype = uri(namespace)

         // othewise root element

         if (uri != null && !(uri.trim()).equals(""))

         {

           doctype = uri;

         }

         else

         {

           doctype = docname;

         }

         MetaCatUtil.debugMessage("DOCNAME-a: " + docname, 30);

         MetaCatUtil.debugMessage("DOCTYPE-a: " + doctype, 30);

       } 

       else if (doctype == null) 

       {

         // because docname is not null and it is declared in dtd

         // so could not be in schema, no namespace

         doctype = docname;

         MetaCatUtil.debugMessage("DOCTYPE-b: " + doctype, 30);

       }

       rootNode.writeNodename(docname);

       try {

         // for validated XML Documents store a reference to XML DB Catalog

         // Because this is select statement and it needn't to roll back if

         // insert document action fialed.

         // In order to decrease DBConnection usage count, we get a new

         // dbconnection from pool

         String catalogid = null;

         DBConnection dbConn = null;

         int serialNumber = -1;

         if ( systemid != null ) {

           try

           {

            // Get dbconnection

            dbConn=DBConnectionPool.getDBConnection

                                          ("DBSAXHandler.startElement");

            serialNumber=dbConn.getCheckOutSerialNumber();

            Statement stmt = dbConn.createStatement();

            ResultSet rs = stmt.executeQuery(

                          "SELECT catalog_id FROM xml_catalog " +

                          "WHERE entry_type = 'DTD' " +

                          "AND public_id = '" + doctype + "'");

            boolean hasRow = rs.next();

            if ( hasRow ) {

              catalogid = rs.getString(1);

            }

            stmt.close();

           }//try

           finally

           {

             // Return dbconnection

             DBConnectionPool.returnDBConnection(dbConn, serialNumber);

           }//finally

         }

         //create documentImpl object by the constructor which can specify

         //the revision

         currentDocument = new DocumentImpl(connection, rootNode.getNodeID(),

                               docname, doctype, docid, revision, action, user,

                               this.pub, catalogid, this.serverCode);

       } catch (Exception ane) {

         throw (new SAXException("Error in DBSaxHandler.startElement " +

                                 action, ane));

       }

     }

     // Create the current node representation

     currentNode = new DBSAXNode(connection, qName, localName, parentNode,

                                 currentDocument.getRootNodeID(),docid,

                                 currentDocument.getDoctype());

     // Add all of the namespaces

     String prefix;

     String nsuri;

     Enumeration prefixes = namespaces.keys();

     while ( prefixes.hasMoreElements() ) {

       prefix = (String)prefixes.nextElement();

       nsuri = (String)namespaces.get(prefix);

       currentNode.setNamespace(prefix, nsuri, docid);

     }

     namespaces = null;

     namespaces = new Hashtable();

     // Add all of the attributes

     for (int i=0; i<atts.getLength(); i++) 

     {

       String attributeName = atts.getQName(i);

       String attributeValue = atts.getValue(i);

       currentNode.setAttribute(attributeName, attributeValue, docid);

       // To handle name space and schema location if the attribute name is

       // xsi:schemaLocation. If the name space is in not in catalog table

       // it will be regeistered.

       if (attributeName != null && 

           attributeName.indexOf(MetaCatServlet.SCHEMALOCATIONKEYWORD) != -1)

       {

         SchemaLocationResolver resolver = 

                                  new SchemaLocationResolver(attributeValue);

         resolver.resolveNameSpace();

       }

     }

     // handle access stuff

     if (localName.equals(ACCESS))

     {

       // if it is in addtionalmetacat

       if (currentNode.getTagName() == DESCRIBES)

       {

         // get the value in current

       }

     }

     // Add the node to the stack, so that any text data can be

     // added as it is encountered

     nodeStack.push(currentNode);

     // Add the node to the vector used by thread for writing XML Index

     nodeIndex.addElement(currentNode);

  }

  /* The run method of xmlIndex thread. It writes XML Index for the document. */

  public void run ()

  {

    DBSAXNode currNode = null;

    DBSAXNode prevNode = null;

    DBConnection dbConn = null;

    int serialNumber = -1;

    String doctype = currentDocument.getDoctype();

    int step = 0;

    int counter = 0;

    try

    {

      // Opening separate db connection for writing XML Index

      dbConn=DBConnectionPool.getDBConnection("DBSAXHandler.run");

      serialNumber=dbConn.getCheckOutSerialNumber();

      dbConn.setAutoCommit(false);

      //the following while loop construct checks to make sure that the docid

      //of the document that we are trying to index is already

      //in the xml_documents table.  if this is not the case, the foreign

      //key relationship between xml_documents and xml_index is temporarily

      //broken causing multiple problems.

      boolean inxmldoc = false;

      long startTime = System.currentTimeMillis();

      while(!inxmldoc)

      {

        String xmlDocumentsCheck = "select distinct docid from xml_documents";

        PreparedStatement xmlDocCheck =

                                 dbConn.prepareStatement(xmlDocumentsCheck);

        // Increase usage count

        dbConn.increaseUsageCount(1);

        xmlDocCheck.execute();

        ResultSet doccheckRS = xmlDocCheck.getResultSet();

        boolean tableHasRows = doccheckRS.next();

        Vector docids = new Vector();

        while(tableHasRows)

        {

          docids.add(doccheckRS.getString(1).trim());

          tableHasRows = doccheckRS.next();

        }

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

        {

          String d = ((String)docids.elementAt(i)).trim();

          if(docid.trim().equals(d))

          {

            inxmldoc = true;

          }

        }

        doccheckRS.close();

        xmlDocCheck.close();

        // make sure the while loop will be ended in reseaonable time

        long stopTime = System.currentTimeMillis();

        if ((stopTime - startTime) > INDEXDELAY)

        {

          throw new Exception("Couldn't find the docid for index build in" +

                              "reseaonable time!");

        }

      }

      // Going through the elements of the document and writing its Index

      Enumeration nodes = nodeIndex.elements();

      while ( nodes.hasMoreElements() ) {

        currNode = (DBSAXNode)nodes.nextElement();

        currNode.updateNodeIndex(dbConn, docid, doctype);

      }

      dbConn.commit();

   }

   catch (Exception e) 

   {

      try 

      {

        dbConn.rollback();

      } 

      catch (SQLException sqle) 

      {}

      MetaCatUtil.debugMessage("Error in DBSAXHandler.run " + 

                                e.getMessage(), 30);

    }

    finally

    {

      DBConnectionPool.returnDBConnection(dbConn, serialNumber);

    }//finally

 }//run

}