Metacat

/**

 *  '$RCSfile$'

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

 *  National Center for Ecological Analysis and Synthesis

 *

 *  Author: Matthew Perry

 *  '$Date$'

 *  '$Revision$'

 *

 *  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

 *

 *  Purpose: Servlet to generate a styled layer descriptor (SLD)

 *           with a filter to restrict features on

 *           a WMS map to given docids

 *

 *  Status: Currently this is just a working stub

 *          with some hardcoded values. Since this needs to be

 *          fired off on every map redraw, we'll need a way to make

 *          the generation of docid list very efficient.

 *

 *  Usage: Append the URL as an "SLD" to any WMS GetMap request

 *    ex: http://server/context/wms?...&SLD=http://server/context/sldfactory?originalSld=data_points_style

import edu.ucsb.nceas.utilities.XMLUtilities;

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 javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.FactoryConfigurationError;

import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.SAXException;

import org.xml.sax.SAXParseException;

import java.io.File;

import java.io.IOException;

 * Class to generate Styled Layer Descriptors allowing geoserver to

 * filter the feature rendering based on various contraints

 * such as permissions, non-spatial queries and skin configuration.

 */

  static Document document;

  static String sld;

   * Handle "GET" method requests from HTTP clients

   *

   * @param request Incoming servlet request.

   * @param response Servlet response.

   */

  throws ServletException, IOException

  {

    handleGetOrPost(request, response);

  }

   * Handle "POST" method requests from HTTP clients

   *

   * @param request Incoming servlet request.

   * @param response Servlet response.

   */

  throws ServletException, IOException

  {

    handleGetOrPost(request, response);

  }

  /**

	 * Modifies the original SLD according to various access contraints and

	 * sends it as the servlet response.

	 *

	 * @param request

	 *            Incoming servlet request.

	 * @param response

	 *            Servlet response.

	 */

	private void handleGetOrPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		String dataset = request.getParameter("originalSld");

		try {

			String certPath = SystemUtil.getContextDir();

			System.out.println(sld);

			response.setContentType("text/xml");

			response.getWriter().write(sld);

		} catch (FileNotFoundException fnf) {

			fnf.printStackTrace();

		} catch (Exception e) {

			e.printStackTrace();

		}

	}

  /**

	 * ogc:Filter to exclude/include certain docids based on user's permissions.

	 * The sld file is specified without path and must exist within geoserver's

	 * styles folder (context/data/styles/*)

	 *

	 * returns SLD document as a String.

	 *

	 * @param filename

	 *            Filename of the base sld.

	 * @todo Implement the doc id list queries for contraints.

	 */

	    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

	     * TODO :

	     *  Get the list of allowable docids due to

	     *    access contraints (based on current logged-in user)

	     *    skin filtering (eg organization name)

	     *    existing non-spatial query (eg taxonomic query)

	     *

	     *  These could ideally be cached as session variables to improve

	     *  speed over running expensive SQL queries on

	     *  each map redraw.

	     *

	     * Combined, these will be a vector of allowed docids that

	     * are to be displayed on the map

	     *

	     * Below is just a hardcoded example of the above...

	     *

	     */

	    allowedDocids.add("nceas.288");

	    allowedDocids.add("nrs.720");

	    String rulesString = "";

		    document = builder.parse( new File(filename) );

		    Element root = document.getDocumentElement();

		    NodeList elemList = document.getElementsByTagName("Rule");

		    Node ruleNode = elemList.item(0);

		    // Get the Element/node comprising the ogc:Filter for all of the above

		    Element filterElement = getFilterElement(document,allowedDocids);

		    // Append the Filter to the ruleNode

		    ruleNode.appendChild(filterElement);

		    // Write new DOM as a string

		    rulesString = XMLUtilities.getDOMTreeAsString((Node) root, true);

	       sxe.printStackTrace();

	    } catch (ParserConfigurationException pce) {

	       pce.printStackTrace();

	    } catch (IOException ioe) {

	       ioe.printStackTrace();

  }

  /**

   * Given a DOM document and a vector of docids,

   * Creates an OGC Filter node

   *

   * @param inDoc	DOM document.

	  Element filterElem = inDoc.createElement("ogc:Filter");

	  String docid = "";

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

		  Element opElem = inDoc.createElement("ogc:PropertyIsEqualTo");

		  Element propertyElem = inDoc.createElement("ogc:PropertyName");

		  Text propertyText = inDoc.createTextNode("docid");

		  propertyElem.appendChild(propertyText);

		  Element literalElem = inDoc.createElement("ogc:Literal");

		  docid = (String)docids.elementAt(i);

		  Text literalText = inDoc.createTextNode(docid);

		  literalElem.appendChild(literalText);

		  opElem.appendChild(propertyElem);

		  opElem.appendChild(literalElem);

		  orElem.appendChild(opElem);

		  // END LOOP

	  }

  }

}