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/**
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* '$RCSfile$'
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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*
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* Author: Matthew Perry
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* '$Date: 2008-07-28 16:07:10 -0700 (Mon, 28 Jul 2008) $'
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* '$Revision: 4167 $'
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Purpose: Servlet to generate a styled layer descriptor (SLD)
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* with a filter to restrict features on
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* a WMS map to given docids
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*
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* Status: Currently this is just a working stub
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* with some hardcoded values. Since this needs to be
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* fired off on every map redraw, we'll need a way to make
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* the generation of docid list very efficient.
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*
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* Usage: Append the URL as an "SLD" to any WMS GetMap request
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* ex: http://server/context/wms?...&SLD=http://server/context/sldfactory?originalSld=data_points_style
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*/
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package edu.ucsb.nceas.metacat.spatial;
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import edu.ucsb.nceas.utilities.XMLUtilities;
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import edu.ucsb.nceas.metacat.util.SystemUtil;
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import javax.servlet.ServletConfig;
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import javax.servlet.ServletContext;
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import javax.servlet.ServletException;
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import javax.servlet.ServletInputStream;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import javax.servlet.http.HttpSession;
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import javax.servlet.http.HttpUtils;
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import javax.servlet.ServletOutputStream;
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import javax.xml.parsers.DocumentBuilder;
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import javax.xml.parsers.DocumentBuilderFactory;
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import javax.xml.parsers.FactoryConfigurationError;
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import javax.xml.parsers.ParserConfigurationException;
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import org.xml.sax.SAXException;
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import org.xml.sax.SAXParseException;
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import java.io.File;
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import java.io.IOException;
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import java.io.FileNotFoundException;
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import java.util.Vector;
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import org.w3c.dom.*;
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/**
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* Class to generate Styled Layer Descriptors allowing geoserver to
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* filter the feature rendering based on various contraints
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* such as permissions, non-spatial queries and skin configuration.
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*/
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public class SldFactory extends HttpServlet {
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static Document document;
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static String sld;
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/**
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* Handle "GET" method requests from HTTP clients
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*
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* @param request Incoming servlet request.
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* @param response Servlet response.
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*/
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public void doGet(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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handleGetOrPost(request, response);
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}
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/**
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* Handle "POST" method requests from HTTP clients
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*
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* @param request Incoming servlet request.
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* @param response Servlet response.
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*/
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public void doPost(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException
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{
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handleGetOrPost(request, response);
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}
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/**
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* Control servlet response depending on the action parameter specified
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* Modifies the original SLD according to various access contraints and
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* sends it as the servlet response.
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*
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* @param request
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* Incoming servlet request.
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* @param response
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* Servlet response.
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*/
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private void handleGetOrPost(HttpServletRequest request, HttpServletResponse response)
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throws ServletException, IOException {
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String dataset = request.getParameter("originalSld");
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try {
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String certPath = SystemUtil.getContextDir();
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String filename = certPath + "/data/styles/" + dataset;
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String sld = getSld(filename);
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System.out.println(sld);
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response.setContentType("text/xml");
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response.getWriter().write(sld);
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} catch (FileNotFoundException fnf) {
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fnf.printStackTrace();
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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/**
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* Given a filename of an existing SLD document, reads the sld and adds an
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* ogc:Filter to exclude/include certain docids based on user's permissions.
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* The sld file is specified without path and must exist within geoserver's
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* styles folder (context/data/styles/*)
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*
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* returns SLD document as a String.
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*
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* @param filename
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* Filename of the base sld.
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* @todo Implement the doc id list queries for contraints.
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*/
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private String getSld(String filename) throws FileNotFoundException
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{
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DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
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Vector allowedDocids = new Vector();
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/*
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* TODO :
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* Get the list of allowable docids due to
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* access contraints (based on current logged-in user)
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* skin filtering (eg organization name)
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* existing non-spatial query (eg taxonomic query)
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*
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* These could ideally be cached as session variables to improve
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* speed over running expensive SQL queries on
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* each map redraw.
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*
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* Combined, these will be a vector of allowed docids that
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* are to be displayed on the map
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*
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* Below is just a hardcoded example of the above...
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*
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*/
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allowedDocids.add("nceas.288");
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allowedDocids.add("nrs.720");
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String rulesString = "";
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try {
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DocumentBuilder builder = factory.newDocumentBuilder();
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document = builder.parse( new File(filename) );
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Element root = document.getDocumentElement();
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NodeList elemList = document.getElementsByTagName("Rule");
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Node ruleNode = elemList.item(0);
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// Get the Element/node comprising the ogc:Filter for all of the above
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Element filterElement = getFilterElement(document,allowedDocids);
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// Append the Filter to the ruleNode
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ruleNode.appendChild(filterElement);
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// Write new DOM as a string
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rulesString = XMLUtilities.getDOMTreeAsString((Node) root, true);
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} catch (SAXException sxe) {
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sxe.printStackTrace();
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} catch (ParserConfigurationException pce) {
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pce.printStackTrace();
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} catch (IOException ioe) {
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ioe.printStackTrace();
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}
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return rulesString;
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}
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/**
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* Given a DOM document and a vector of docids,
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* Creates an OGC Filter node
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*
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* @param inDoc DOM document.
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* @param docids Vector of documents allowed in the map.
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*/
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private Element getFilterElement(Document inDoc, Vector docids)
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{
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Element filterElem = inDoc.createElement("ogc:Filter");
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Element orElem = inDoc.createElement("ogc:Or");
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String docid = "";
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// Begin loop thru vector of allowed docids
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for (int i = 0; i < docids.size(); i++) {
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Element opElem = inDoc.createElement("ogc:PropertyIsEqualTo");
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Element propertyElem = inDoc.createElement("ogc:PropertyName");
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Text propertyText = inDoc.createTextNode("docid");
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propertyElem.appendChild(propertyText);
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Element literalElem = inDoc.createElement("ogc:Literal");
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docid = (String)docids.elementAt(i);
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Text literalText = inDoc.createTextNode(docid);
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literalElem.appendChild(literalText);
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opElem.appendChild(propertyElem);
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opElem.appendChild(literalElem);
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orElem.appendChild(opElem);
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// END LOOP
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}
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filterElem.appendChild(orElem);
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return filterElem;
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}
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}
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