/**
* '$RCSfile$'
* 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
*/
package edu.ucsb.nceas.metacat.spatial;
import edu.ucsb.nceas.utilities.XMLUtilities;
import edu.ucsb.nceas.metacat.util.SystemUtil;
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;
import java.io.FileNotFoundException;
import java.util.Vector;
import org.w3c.dom.*;
/**
* 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.
*/
public class SldFactory extends HttpServlet {
static Document document;
static String sld;
/**
* Handle "GET" method requests from HTTP clients
*
* @param request Incoming servlet request.
* @param response Servlet response.
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
handleGetOrPost(request, response);
}
/**
* Handle "POST" method requests from HTTP clients
*
* @param request Incoming servlet request.
* @param response Servlet response.
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
handleGetOrPost(request, response);
}
/**
* Control servlet response depending on the action parameter specified
* 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();
String filename = certPath + "/data/styles/" + dataset;
String sld = getSld(filename);
System.out.println(sld);
response.setContentType("text/xml");
response.getWriter().write(sld);
} catch (FileNotFoundException fnf) {
fnf.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Given a filename of an existing SLD document, reads the sld and adds an
* 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.
*/
private String getSld(String filename) throws FileNotFoundException
{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
Vector allowedDocids = new Vector();
/*
* 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 = "";
try {
DocumentBuilder builder = factory.newDocumentBuilder();
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);
} catch (SAXException sxe) {
sxe.printStackTrace();
} catch (ParserConfigurationException pce) {
pce.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
}
return rulesString;
}
/**
* Given a DOM document and a vector of docids,
* Creates an OGC Filter node
*
* @param inDoc DOM document.
* @param docids Vector of documents allowed in the map.
*/
private Element getFilterElement(Document inDoc, Vector docids)
{
Element filterElem = inDoc.createElement("ogc:Filter");
Element orElem = inDoc.createElement("ogc:Or");
String docid = "";
// Begin loop thru vector of allowed docids
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
}
filterElem.appendChild(orElem);
return filterElem;
}
}