Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that represents a structured query, and can be 

 *             constructed from an XML serialization conforming to 

 *             pathquery.dtd. The printSQL() method can be used to print 

 *             a SQL serialization of the query.

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

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones

 *    Release: @release@

 *

 *   '$Author: tao $'

 *     '$Date: 2003-01-07 17:03:42 -0800 (Tue, 07 Jan 2003) $'

 * '$Revision: 1354 $'

 *

 * 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 edu.ucsb.nceas.dbadapter.*;

import java.io.*;

import java.util.Hashtable;

import java.util.Stack;

import java.util.Vector;

import java.util.Enumeration;

import org.xml.sax.Attributes;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.SAXParseException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.XMLReaderFactory;

import org.xml.sax.helpers.DefaultHandler;

/**

 * A Class that represents a structured query, and can be 

 * constructed from an XML serialization conforming to @see pathquery.dtd. 

 * The printSQL() method can be used to print a SQL serialization of the query.

 */

public class QuerySpecification extends DefaultHandler {

  /** flag determining whether extended query terms are present */

  private boolean containsExtendedSQL=false;

  /** Identifier for this query document */

  private String meta_file_id;

  /** Title of this query */

  private String queryTitle;

  /** List of document types to be returned using package back tracing */

  private Vector returnDocList;

  /** List of document types to be searched */

  private Vector filterDocList;

  /** List of fields to be returned in result set */

  private Vector returnFieldList;

  /** List of users owning documents to be searched */

  private Vector ownerList;

  /** List of sites/scopes used to constrain search */

  private Vector siteList;

  /** The root query group that contains the recursive query constraints */

  private QueryGroup query = null;

  // Query data structures used temporarily during XML parsing

  private Stack elementStack;

  private Stack queryStack;

  private String currentValue;

  private String currentPathexpr;

  private String parserName = null;

  private String accNumberSeparator = null;

  private static final AbstractDatabase dbAdapter = MetaCatUtil.dbAdapter;

  private int countPercentageSearchItem = 0;

  private boolean percentageSearch = false;

  private String userName = null;

  private static final String PUBLIC = "public";

  private String [] group = null;

  public static final String ATTRIBUTESYMBOL = "@";

  private boolean hasAttributeReturnField = false;

  private Hashtable attributeReturnList = new Hashtable();

  private int countAttributeReturnField = 0;

  /**

   * construct an instance of the QuerySpecification class 

   *

   * @param queryspec the XML representation of the query (should conform

   *                  to pathquery.dtd) as a Reader

   * @param parserName the fully qualified name of a Java Class implementing

   *                  the org.xml.sax.XMLReader interface

   */

  public QuerySpecification( Reader queryspec, String parserName,

         String accNumberSeparator ) throws IOException {

    super();

    // Initialize the class variables

    returnDocList = new Vector();

    filterDocList = new Vector();

    elementStack = new Stack();

    queryStack   = new Stack();

    returnFieldList = new Vector();

    ownerList = new Vector();

    siteList = new Vector();

    this.parserName = parserName;

    this.accNumberSeparator = accNumberSeparator;

    // Initialize the parser and read the queryspec

    XMLReader parser = initializeParser();

    if (parser == null) {

      System.err.println("SAX parser not instantiated properly.");

    }

    try {

      parser.parse(new InputSource(queryspec));

    } catch (SAXException e) {

      System.err.println("error parsing data in " + 

                         "QuerySpecification.QuerySpecification");

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

    }

  }

  /**

   * construct an instance of the QuerySpecification class 

   *

   * @param queryspec the XML representation of the query (should conform

   *                  to pathquery.dtd) as a String

   * @param parserName the fully qualified name of a Java Class implementing

   *                  the org.xml.sax.Parser interface

   */

  public QuerySpecification( String queryspec, String parserName,

         String accNumberSeparator) throws IOException {

    this(new StringReader(queryspec), parserName, accNumberSeparator);

  }

  /**

   * Method to set user name

   *

   * @param myName  the user name

   */

  public void setUserName(String myName)

  {

    this.userName = myName;

  }

  /**

   * Method to set user group

   *

   * @param myGroup  the user group

   */

  public void setGroup(String [] myGroup)

  {

    this.group = myGroup;

  }

  /**

   * Method to indicate this query is a percentage search

   */

  public boolean isPercentageSearch()

  {

    return percentageSearch;

  }

  /*

   * Method to get owner query. If it is owner it has all permission

   */

  private String createOwerQuery()

  {

    String ownerQuery = null;

    ownerQuery = "SELECT docid FROM xml_documents WHERE user_owner ='" +

                  PUBLIC + "'";

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

    {

      ownerQuery = ownerQuery + " OR user_owner ='"+ userName +"'";

    }

    if (group != null)

    {

      for (int i = 0; i< group.length; i++)

      {

        String groupUint = group[i];

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

        {

          ownerQuery = ownerQuery +" OR user_owner = '" + groupUint + "'";

        }//if

      }//for

    }

    MetaCatUtil.debugMessage("OwnerQuery: "+ownerQuery, 30);

    return ownerQuery;

  }

  /*

   * Method to create query for xml_access, this part is to get docid list which

   * have a allow rule for a given user

   */

  private String createAllowRuleQuery()

  {

    String allowQuery = null;

    allowQuery ="SELECT docid from xml_access WHERE ";

    // add allow rule for user name

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

    {

      allowQuery = allowQuery +"(principal_name = '" + userName 

                              +"' AND perm_type = 'allow'"

                              +" AND (permission='4' OR permission='7'))";

    }

    // add allow rule for public

    allowQuery = allowQuery +"OR (principal_name = '" + PUBLIC 

                              +"' AND perm_type = 'allow'"

                              +" AND (permission='4' OR permission='7'))";

    // add allow rule for group

    if (group != null)

    {

      for (int i = 0; i< group.length; i++)

      {

        String groupUint = group[i];

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

        {

          allowQuery = allowQuery +" OR (principal_name = '" + groupUint 

                              +"' AND perm_type = 'allow'"

                              +" AND (permission='4' OR permission='7'))";

        }//if

      }//for

    }//if

    MetaCatUtil.debugMessage("allow query is: "+ allowQuery, 30);

    return allowQuery;

  }

   /*

   * Method to create query for xml_access, this part is to get docid list which

   * have a deny rule and perm_order is allowFirst for a given user. This means

   * the user will be denied to read

   */

  private String createDenyRuleQuery()

  {

    String denyQuery = null;

    denyQuery ="SELECT docid from xml_access WHERE ";

    // add deny rule for user name

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

    {

      denyQuery = denyQuery +"(principal_name = '" + userName 

                              +"' AND perm_type = 'deny' "

                              +"AND perm_order ='allowFirst'"

                              +" AND (permission='4' OR permission='7'))";

    }

    // add deny rule for public

    denyQuery = denyQuery +"OR (principal_name = '" + PUBLIC 

                               +"' AND perm_type = 'deny' "

                               +"AND perm_order ='allowFirst'"

                               +" AND (permission='4' OR permission='7'))";

    // add allow rule for group

    if (group != null)

    {

      for (int i = 0; i< group.length; i++)

      {

        String groupUint = group[i];

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

        {

          denyQuery = denyQuery +" OR (principal_name = '" + groupUint 

                                +"' AND perm_type = 'deny' "

                                +"AND perm_order ='allowFirst'"

                                +" AND (permission='4' OR permission='7'))";

        }//if

      }//for

    }//if

    MetaCatUtil.debugMessage("denyquery is: "+ denyQuery, 30);

    return denyQuery;

  }

  /**

   * Method to append a access control query to SQL. So in DBQuery class, we can

   * get docid from both user specified query and access control query. We don't

   * need to checking permission after we get the doclist. It will be good to 

   * performance

   *

   */

  public String getAccessQuery()

  {

    String accessQuery = null;

    String onwer = createOwerQuery();

    String allow = createAllowRuleQuery();

    String deny = createDenyRuleQuery();

    accessQuery = " AND (docid IN("+ onwer + ")";

    accessQuery = accessQuery + " OR (docid IN (" + allow + ")" 

                 + " AND docid NOT IN ("+ deny + ")))";

    MetaCatUtil.debugMessage("accessquery is: "+ accessQuery, 30);

    return accessQuery;

  }

  /** Main routine for testing */

  static public void main(String[] args) {

     if (args.length < 1) {

       System.err.println("Wrong number of arguments!!!");

       System.err.println("USAGE: java QuerySpecification <xmlfile>");

       return;

     } else {

       int i = 0;

       boolean useXMLIndex = true;

       if ( args[i].equals( "-noindex" ) ) {

         useXMLIndex = false;

         i++;

       }

       String xmlfile  = args[i];

       try {

         MetaCatUtil util = new MetaCatUtil();

         FileReader xml = new FileReader(new File(xmlfile));

         QuerySpecification qspec = 

                 new QuerySpecification(xml, util.getOption("saxparser"),

                                        util.getOption("accNumberSeparator"));

         System.out.println(qspec.printSQL(useXMLIndex));

       } catch (IOException e) {

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

       }

     }

  }

  /**

   * Returns true if the parsed query contains and extended xml query 

   * (i.e. there is at least one <returnfield> in the pathquery document)

   */

  public boolean containsExtendedSQL()

  {

    if(containsExtendedSQL)

    {

      return true;

    }

    else

    {

      return false;

    }

  }

  /**

   * A method to get if the query has an attribute return field

   */

  public boolean containAttributeReturnField()

  {

    return hasAttributeReturnField;

  }

  /**

   * Accessor method to return the identifier of this Query

   */

  public String getIdentifier()

  {

    return meta_file_id;

  }

  /**

   * method to set the identifier of this query

   */

  public void setIdentifier(String id) {

    this.meta_file_id = id;

  }

  /**

   * Accessor method to return the title of this Query

   */

  public String getQueryTitle()

  {

    return queryTitle;

  }

  /**

   * method to set the title of this query

   */

  public void setQueryTitle(String title)

  {

    this.queryTitle = title;

  }

  /**

   * Accessor method to return a vector of the return document types as

   * defined in the <returndoctype> tag in the pathquery dtd.

   */

  public Vector getReturnDocList()

  {

    return this.returnDocList;

  }

  /**

   * method to set the list of return docs of this query

   */

  public void setReturnDocList(Vector returnDocList)

  {

    this.returnDocList = returnDocList;

  }

  /**

   * Accessor method to return a vector of the filter doc types as

   * defined in the <filterdoctype> tag in the pathquery dtd.

   */

  public Vector getFilterDocList()

  {

    return this.filterDocList;

  }

  /**

   * method to set the list of filter docs of this query

   */

  public void setFilterDocList(Vector filterDocList)

  {

    this.filterDocList = filterDocList;

  }

  /**

   * Accessor method to return a vector of the extended return fields as

   * defined in the <returnfield> tag in the pathquery dtd.

   */

  public Vector getReturnFieldList()

  {

    return this.returnFieldList; 

  }

  /**

   * method to set the list of fields to be returned by this query

   */

  public void setReturnFieldList(Vector returnFieldList)

  {

    this.returnFieldList = returnFieldList;

  }

  /**

   * Accessor method to return a vector of the owner fields as

   * defined in the <owner> tag in the pathquery dtd.

   */

  public Vector getOwnerList()

  {

    return this.ownerList;

  }

  /**

   * method to set the list of owners used to constrain this query

   */

  public void setOwnerList(Vector ownerList)

  {

    this.ownerList = ownerList;

  }

  /**

   * Accessor method to return a vector of the site fields as

   * defined in the <site> tag in the pathquery dtd.

   */

  public Vector getSiteList()

  {

    return this.siteList;

  }

  /**

   * method to set the list of sites used to constrain this query

   */

  public void setSiteList(Vector siteList)

  {

    this.siteList = siteList;

  }

  /**

   * get the QueryGroup used to express query constraints

   */

  public QueryGroup getQueryGroup()

  {

    return query;

  }

  /**

   * Set up the SAX parser for reading the XML serialized query

   */

  private XMLReader initializeParser() {

    XMLReader parser = null;

    // Set up the SAX document handlers for parsing

    try {

      // Get an instance of the parser

      parser = XMLReaderFactory.createXMLReader(parserName);

      // Set the ContentHandler to this instance

      parser.setContentHandler(this);

      // Set the error Handler to this instance

      parser.setErrorHandler(this);

    } catch (Exception e) {

       System.err.println("Error in QuerySpcecification.initializeParser " + 

                           e.toString());

    }

    return parser;

  }

  /**

   * callback method used by the SAX Parser when the start tag of an 

   * element is detected. Used in this context to parse and store

   * the query information in class variables.

   */

  public void startElement (String uri, String localName, 

                            String qName, Attributes atts) 

         throws SAXException {

    BasicNode currentNode = new BasicNode(localName);

    // add attributes to BasicNode here

    if (atts != null) {

      int len = atts.getLength();

      for (int i = 0; i < len; i++) {

        currentNode.setAttribute(atts.getLocalName(i), atts.getValue(i));

      }

    }

    elementStack.push(currentNode); 

    if (currentNode.getTagName().equals("querygroup")) {

      QueryGroup currentGroup = new QueryGroup(

                                currentNode.getAttribute("operator"));

      if (query == null) {

        query = currentGroup;

      } else {

        QueryGroup parentGroup = (QueryGroup)queryStack.peek();

        parentGroup.addChild(currentGroup);

      }

      queryStack.push(currentGroup);

    }

  }

  /**

   * callback method used by the SAX Parser when the end tag of an 

   * element is detected. Used in this context to parse and store

   * the query information in class variables.

   */

  public void endElement (String uri, String localName,

                          String qName) throws SAXException {

    BasicNode leaving = (BasicNode)elementStack.pop(); 

    if (leaving.getTagName().equals("queryterm")) {

      boolean isCaseSensitive = (new Boolean(

              leaving.getAttribute("casesensitive"))).booleanValue();

      QueryTerm currentTerm = null;

      if (currentPathexpr == null) {

        currentTerm = new QueryTerm(isCaseSensitive,

                      leaving.getAttribute("searchmode"),currentValue);

      } else {

        currentTerm = new QueryTerm(isCaseSensitive,

                      leaving.getAttribute("searchmode"),currentValue,

                      currentPathexpr);

      }

      QueryGroup currentGroup = (QueryGroup)queryStack.peek();

      currentGroup.addChild(currentTerm);

      currentValue = null;

      currentPathexpr = null;

    } else if (leaving.getTagName().equals("querygroup")) {

      QueryGroup leavingGroup = (QueryGroup)queryStack.pop();

    }

  }

  /**

   * callback method used by the SAX Parser when the text sequences of an 

   * xml stream are detected. Used in this context to parse and store

   * the query information in class variables.

   */

  public void characters(char ch[], int start, int length) {

    String inputString = new String(ch, start, length);

    BasicNode currentNode = (BasicNode)elementStack.peek(); 

    String currentTag = currentNode.getTagName();

    if (currentTag.equals("meta_file_id")) {

      meta_file_id = inputString;

    } else if (currentTag.equals("querytitle")) {

      queryTitle = inputString;

    } else if (currentTag.equals("value")) {

      currentValue = inputString;

    } else if (currentTag.equals("pathexpr")) {

      currentPathexpr = inputString;

    } else if (currentTag.equals("returndoctype")) {

      returnDocList.add(inputString);

    } else if (currentTag.equals("filterdoctype")) {

      filterDocList.add(inputString);

    } else if (currentTag.equals("returnfield")) {

      // make sure if return fields has an attribute or not

      if (inputString.indexOf(ATTRIBUTESYMBOL) ==-1)

      {

        // no attribute value will be returned

        returnFieldList.add(inputString);

        containsExtendedSQL = true;

      }

      else

      {

        // has a attribute return field

        // divied the return filed into two parts, one is path and the

        // other is attribue name

        String returnPath = newPathExpressionWithOutAttribute(inputString);

        String attributeName = getAttributeName(inputString);

        Vector pathInfo = new Vector();

        // the vector has the information about return path and attributename

        pathInfo.addElement(returnPath);

        pathInfo.addElement(attributeName);

        // put the vector into a hash table. The reseaon why don't put

        // return path or attributename as a key is because they are not unique

        attributeReturnList.put

                            (new Integer(countAttributeReturnField), pathInfo);

        countAttributeReturnField++;

        hasAttributeReturnField = true;

        containsExtendedSQL = true;

      }

    } else if (currentTag.equals("filterdoctype")) {

      filterDocList.add(inputString);

    } else if (currentTag.equals("owner")) {

      ownerList.add(inputString);

    } else if (currentTag.equals("site")) {

      siteList.add(inputString);

    }

  }

  /**

   * create a SQL serialization of the query that this instance represents

   */

  public String printSQL(boolean useXMLIndex) {

    StringBuffer self = new StringBuffer();

    self.append("SELECT docid,docname,doctype,");

    self.append("date_created, date_updated, rev ");

    self.append("FROM xml_documents WHERE docid IN (");

    // This determines the documents that meet the query conditions

    self.append(query.printSQL(useXMLIndex));

    self.append(") ");

    // Add SQL to filter for doctypes requested in the query

    // This is an implicit OR for the list of doctypes. Only doctypes in this

    // list will be searched if the tag is present

    if (!filterDocList.isEmpty()) {

      boolean firstdoctype = true;

      self.append(" AND ("); 

      Enumeration en = filterDocList.elements();

      while (en.hasMoreElements()) {

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

        if (firstdoctype) {

           firstdoctype = false;

           self.append(" doctype = '" + currentDoctype + "'"); 

        } else {

          self.append(" OR doctype = '" + currentDoctype + "'"); 

        }

      }

      self.append(") ");

    }

    // Add SQL to filter for owners requested in the query

    // This is an implicit OR for the list of owners

    if (!ownerList.isEmpty()) {

      boolean first = true;

      self.append(" AND ("); 

      Enumeration en = ownerList.elements();

      while (en.hasMoreElements()) {

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

        if (first) {

           first = false;

           self.append(" user_owner = '" + current + "'"); 

        } else {

          self.append(" OR user_owner = '" + current + "'"); 

        }

      }

      self.append(") ");

    }

    // Add SQL to filter for sites requested in the query

    // This is an implicit OR for the list of sites

    if (!siteList.isEmpty()) {

      boolean first = true;

      self.append(" AND ("); 

      Enumeration en = siteList.elements();

      while (en.hasMoreElements()) {

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

        if (first) {

           first = false;

           self.append(" SUBSTR(docid, 1, INSTR(docid, '" +

               accNumberSeparator + "')-1) = '" + current + "'"); 

        } else {

          self.append(" OR SUBSTR(docid, 1, INSTR(docid, '" +

               accNumberSeparator + "')-1) = '" + current + "'"); 

        }

      }

      self.append(") ");

    }

    // if there is only one percentage search item, this query is a percentage

    // search query

    if (countPercentageSearchItem ==1)

    {

      percentageSearch =true;

    }

    return self.toString();

  }

  /**

   * This method prints sql based upon the <returnfield> tag in the

   * pathquery document.  This allows for customization of the 

   * returned fields

   * @param doclist the list of document ids to search by

   */

  public String printExtendedSQL(String doclist)

  {  

    StringBuffer self = new StringBuffer();

    self.append("select xml_nodes.docid, xml_index.path, xml_nodes.nodedata ");

    self.append("from xml_index, xml_nodes where xml_index.nodeid=");

    self.append("xml_nodes.parentnodeid and (xml_index.path like '");

    boolean firstfield = true;

    //put the returnfields into the query

    //the for loop allows for multiple fields

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

    {

      if(firstfield)

      {

        firstfield = false;

        self.append((String)returnFieldList.elementAt(i));

        self.append("' ");

      }

      else

      {

        self.append("or xml_index.path like '");

        self.append((String)returnFieldList.elementAt(i));

        self.append("' ");

      }

    }

    self.append(") AND xml_nodes.docid in (");

    //self.append(query.printSQL());

    self.append(doclist);

    self.append(")");

    self.append(" AND xml_nodes.nodetype = 'TEXT'");

    return self.toString();

  }

  /**

   * This method prints sql based upon the returnfield tag in the

   * pathquery document has an attribute.  This allows for customization of the 

   * returned fields

   * @param doclist the list of document ids to search by

   */

  public String printAttributeQuery(String doclist)

  {

    StringBuffer self = new StringBuffer();

    self.append("select xml_nodes.docid, xml_index.path, ");

    self.append("xml_nodes.nodedata, xml_nodes.nodename ");

    self.append("from xml_index, xml_nodes where xml_index.nodeid=");

    self.append("xml_nodes.parentnodeid and (");

    boolean firstfield = true;

    //put the returnfields attributes into the query

    //the for loop allows for multiple fields and attributes

    Enumeration returnAttributes = attributeReturnList.elements();

    while (returnAttributes.hasMoreElements())

    {

      Vector currentVector = (Vector)returnAttributes.nextElement();

      String returnPath = (String)currentVector.elementAt(0);

      String attributeName = (String)currentVector.elementAt(1);

      if(firstfield)

      {

        firstfield = false;

        self.append("( xml_index.path like '");

        self.append(returnPath);

        self.append("' AND xml_nodes.nodename like '");

        self.append(attributeName);

        self.append("') ");

      }

      else

      {

        self.append(" or ( xml_index.path like '");

        self.append(returnPath);

        self.append("' AND xml_nodes.nodename like '");

        self.append(attributeName);

        self.append("') "); 

      }

    }

    self.append(") AND xml_nodes.docid in (");

    //self.append(query.printSQL());

    self.append(doclist);

    self.append(")");

    self.append(" AND xml_nodes.nodetype = 'ATTRIBUTE'");

    MetaCatUtil.debugMessage("Attribute query: "+self.toString(), 30);

    return self.toString();

  }

  public static String printRelationSQL(String docid)

  {

    StringBuffer self = new StringBuffer();

    self.append("select subject, relationship, object, subdoctype, ");

    self.append("objdoctype from xml_relation ");

    self.append("where docid like '").append(docid).append("'");

    return self.toString();

  }

  /**

   * Prints sql that returns all relations in the database.

   */

  public static String printPackageSQL()

  {

    StringBuffer self = new StringBuffer();

    self.append("select z.nodedata, x.nodedata, y.nodedata from ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/subject') s, (select nodeid, parentnodeid ");

    self.append("from xml_index where path like ");

    self.append("'triple/relationship') rel, ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/object') o, ");

    self.append("xml_nodes x, xml_nodes y, xml_nodes z ");

    self.append("where s.parentnodeid = rel.parentnodeid ");

    self.append("and rel.parentnodeid = o.parentnodeid ");

    self.append("and x.parentnodeid in (rel.nodeid) ");

    self.append("and y.parentnodeid in (o.nodeid) ");

    self.append("and z.parentnodeid in (s.nodeid) ");

    //self.append("and z.nodedata like '%");

    //self.append(docid);

    //self.append("%'");

    return self.toString();

  }

  /**

   * Prints sql that returns all relations in the database that were input

   * under a specific docid

   * @param docid the docid to search for.

   */

  public static String printPackageSQL(String docid)

  {

    StringBuffer self = new StringBuffer();

    self.append("select z.nodedata, x.nodedata, y.nodedata from ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/subject') s, (select nodeid, parentnodeid ");

    self.append("from xml_index where path like ");

    self.append("'triple/relationship') rel, ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/object') o, ");

    self.append("xml_nodes x, xml_nodes y, xml_nodes z ");

    self.append("where s.parentnodeid = rel.parentnodeid ");

    self.append("and rel.parentnodeid = o.parentnodeid ");

    self.append("and x.parentnodeid in (rel.nodeid) ");

    self.append("and y.parentnodeid in (o.nodeid) ");

    self.append("and z.parentnodeid in (s.nodeid) ");

    self.append("and z.docid like '").append(docid).append("'");

    return self.toString();

  }

  /**

   * Returns all of the relations that has a certain docid in the subject

   * or the object.

   * 

   * @param docid the docid to search for

   */

  public static String printPackageSQL(String subDocidURL, String objDocidURL)

  {

    StringBuffer self = new StringBuffer();

    self.append("select z.nodedata, x.nodedata, y.nodedata from ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/subject') s, (select nodeid, parentnodeid ");

    self.append("from xml_index where path like ");

    self.append("'triple/relationship') rel, ");

    self.append("(select nodeid, parentnodeid from xml_index where path like ");

    self.append("'triple/object') o, ");

    self.append("xml_nodes x, xml_nodes y, xml_nodes z ");

    self.append("where s.parentnodeid = rel.parentnodeid ");

    self.append("and rel.parentnodeid = o.parentnodeid ");

    self.append("and x.parentnodeid in (rel.nodeid) ");

    self.append("and y.parentnodeid in (o.nodeid) ");

    self.append("and z.parentnodeid in (s.nodeid) ");

    self.append("and (z.nodedata like '");

    self.append(subDocidURL);

    self.append("' or y.nodedata like '");

    self.append(objDocidURL);

    self.append("')");

    return self.toString();

  }

  public static String printGetDocByDoctypeSQL(String docid)

  {

    StringBuffer self = new StringBuffer();

    self.append("SELECT docid,docname,doctype,");

    self.append("date_created, date_updated ");

    self.append("FROM xml_documents WHERE docid IN (");

    self.append(docid).append(")");

    return self.toString();

  }

  /**

   * create a String description of the query that this instance represents.

   * This should become a way to get the XML serialization of the query.

   */

  public String toString() {

    return "meta_file_id=" + meta_file_id + "\n" + query;

//DOCTITLE attr cleared from the db

//    return "meta_file_id=" + meta_file_id + "\n" + 

//           "querytitle=" + querytitle + "\n" + query;

  }

  /* A method to get rid of attribute part in path expression*/

  public static String newPathExpressionWithOutAttribute(String pathExpression)

  {

      if (pathExpression == null)

      {

        return null;

      }

      int index = pathExpression.lastIndexOf(ATTRIBUTESYMBOL);

      String newExpression = null;

      if (index != 1)

      {

        newExpression=pathExpression.substring(0, index-1);

      } 

      MetaCatUtil.debugMessage("The path expression without attributes: )" + 

                               newExpression, 30);

      return newExpression;

  }