/**
* SiRPACServlet - Simple RDF Parser & Compiler Servlet wrapper
*
* Copyright © World Wide Web Consortium, (Massachusetts Institute of
* Technology, Institut National de Recherche en Informatique et en
* Automatique, Keio University).
*
* All Rights Reserved.
*
* Please see the full Copyright clause at
* <http://www.w3.org/Consortium/Legal/copyright-software.html>
*
* This servlet is a wrapper for the SiRPAC RDF parser. The servlet
* expects the following variables through the POST method:
*
* 1. "RDF" - the RDF/XML document
* 2. "BAGS" - if "on", each Description should have its own Bag;
* the default is not to do this.
* 3. "STREAM" if "on", the stream mode is turned off so that aboutEach
* and aboutEachPrefix are supported.
*
* @author Art Barstow <barstow@w3.org>
*
* The graphics package is AT&T's GraphVis tool.
*/
package org.w3c.rdf.examples;
import java.io.*;
import java.util.StringTokenizer;
import java.util.Enumeration;
import javax.servlet.*;
import javax.servlet.http.*;
import org.xml.sax.InputSource;
import org.xml.sax.Parser;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.*;
import org.w3c.rdf.model.*;
import org.w3c.rdf.syntax.*;
import org.w3c.rdf.syntax.RDFConsumer;
import org.w3c.rdf.util.xml.DumpConsumer;
import org.w3c.rdf.util.xml.ErrorStore;
import org.w3c.rdf.implementation.model.StatementImpl;
import org.w3c.rdf.implementation.model.NodeFactoryImpl;
import org.w3c.rdf.implementation.syntax.sirpac.*;
public class SiRPACServlet extends HttpServlet
{
final static public String REVISION = "$Id: SiRPACServlet.java,v 1.11 2000/10/17 22:58:42 barstow Exp $";
// The email address for bug reports
private static final String MAIL_TO = "barstow@w3.org";
// Names of the POST parameters
// The XML'ized RDF
private static final String POST_TEXT = "RDF";
// Flag for turning on treating each Description as a bag
private static final String POST_BAG = "BAGS";
// Flag for turning off SiRPAC's stream parsing mode
private static final String POST_STREAM_MODE = "STREAM";
// Names of the servlet's parameters
private static final String SIRPAC_TMP_DIR = "SIRPAC_TMP_DIR";
private static final String GRAPH_VIZ_ROOT = "GRAPH_VIZ_ROOT";
private static final String GRAPH_VIZ_PATH = "GRAPH_VIZ_PATH";
private static final String GRAPH_VIZ_LIB_DIR = "GRAPH_VIZ_LIB_DIR";
private static final String GRAPH_VIZ_FONT_DIR = "GRAPH_VIZ_FONT_DIR";
// Variables for the servlet's parameters
private static String m_SiRPACTmpDir = null;
private static String m_GraphVizPath = null;
private static String m_GraphVizFontDir = null;
private static String m_GraphVizLibDir = null;
// Names of environment variable need by GraphVis
private static String DOTFONTPATH = "DOTFONTPATH";
private static String LD_LIBRARY_PATH = "LD_LIBRARY_PATH";
// Names used for temporary files
private static final String TMP_FILE_PREFIX = "sirpac_";
private static final String TMP_DIR_SUFFIX = ".tmp";
private static final String DOT_SUFFIX = ".dot";
private static final String GIF_SUFFIX = ".gif";
// Default GraphViz parameter names and their default values
private static final String NODE_COLOR = "NODE_COLOR";
private static final String DEFAULT_NODE_COLOR = "black";
private static final String NODE_TEXT_COLOR = "NODE_TEXT_COLOR";
private static final String DEFAULT_NODE_TEXT_COLOR = "black";
private static final String EDGE_COLOR = "EDGE_COLOR";
private static final String DEFAULT_EDGE_COLOR = "black";
private static final String EDGE_TEXT_COLOR = "EDGE_TEXT_COLOR";
private static final String DEFAULT_EDGE_TEXT_COLOR = "black";
private static final String ORIENTATION = "ORIENTATION";
private static final String DEFAULT_ORIENTATION = "TB"; // Top to Bottom
private static final String FONT_SIZE = "FONT_SIZE";
private static final String DEFAULT_FONT_SIZE = "10";
// Fonts are not currently configurable
private static final String DEFAULT_FONT = "arial";
// Servlet name
private static final String SERVLET_NAME = "SiRPACServlet";
// The parser
private SiRPAC m_sirpac = null;
// The error handler
private ErrorStore m_errorHandler;
/*
* Create a File object in the m_SiRPACTmpDir directory
*
*@param directory the file's directory
*@param prefix the file's prefix name (not its directory)
*@param suffix the file's suffix or extension name
*@return a File object if a temporary file is created; null otherwise
*/
private File createTempFile (String directory, String prefix, String suffix) {
File f;
try {
File d = new File(directory);
f = File.createTempFile(prefix, suffix, d);
} catch (Exception e) {
return null;
}
return f;
}
/*
* Invokes the GraphVis program to create a GIF image from the
* the given DOT data file
*
*@param dotFileName the name of the DOT data file
*@param gifFileName the name of the GIF data file
*@return true if success; false if any failure occurs
*/
private boolean generateGifFile(String dotFileName, String gifFileName) {
String environment[] = {DOTFONTPATH + "=" + m_GraphVizFontDir,
LD_LIBRARY_PATH + "=" + m_GraphVizLibDir};
String cmdArray[] = {m_GraphVizPath, "-Tgif", "-o", gifFileName, dotFileName};
Runtime rt = Runtime.getRuntime();
try {
Process p = rt.exec(cmdArray, environment);
p.waitFor();
} catch (Exception e) {
return false;
}
return true;
}
/*
* Returns a parameter from a request or the parameter's default
* value.
*
*@param req a Servlet request
*@return if the request contains the specfied parameter its value
* in the request is returned; otherwise its default value is
* returned
*/
private String getParameter(HttpServletRequest req, String param, String defString) {
String s = req.getParameter(param);
return (s == null) ? defString : s;
}
/*
* If the request contains any graph-related parameters, pass them
* to the graph consumer for handling
*
*@param req the response
*@param consumer the GraphViz consumer
*/
private void processGraphParameters (HttpServletRequest req, GraphVizDumpConsumer consumer) {
// Look for colors
String s;
String nodeColor = getParameter (req, NODE_COLOR, DEFAULT_NODE_COLOR);
String nodeTextColor = getParameter (req, NODE_TEXT_COLOR, DEFAULT_NODE_TEXT_COLOR);
String edgeColor = getParameter (req, EDGE_COLOR, DEFAULT_EDGE_COLOR);
String edgeTextColor = getParameter (req, EDGE_TEXT_COLOR, DEFAULT_EDGE_TEXT_COLOR);
String fontSize = getParameter (req, FONT_SIZE, DEFAULT_FONT_SIZE);
// Orientation must be either
String orientation = req.getParameter (ORIENTATION);
if (orientation.equals("Left to Right"))
orientation = "LR";
else
orientation = DEFAULT_ORIENTATION;
// Add an attribute for all of the graph's nodes
consumer.addGraphAttribute("node [fontname=" + DEFAULT_FONT +
",fontsize=" + fontSize +
",color=" + nodeColor +
",fontcolor=" + nodeTextColor + "]");
// Add an attribute for all of the graph's edges
consumer.addGraphAttribute("edge [fontname=" + DEFAULT_FONT +
",fontsize=" + fontSize +
",color=" + edgeColor +
",fontcolor=" + edgeTextColor + "]");
// Add an attribute for the orientation
consumer.addGraphAttribute("rankdir=" + orientation + ";");
}
/*
* Generate a graph of the RDF data model
*
*@param out the servlet's output stream
*@param rdf the RDF text
*@param req a Servlet request
*/
private void generateGraph (ServletOutputStream out, String rdf, HttpServletRequest req) {
try {
out.println("<hr title=\"visualisation\">");
out.println("<h3>Graph of the data model</h3>");
// Stop if any of the parameters are missing
if (m_SiRPACTmpDir == null || m_GraphVizPath == null ||
m_GraphVizFontDir == null || m_GraphVizLibDir == null) {
// Put the paths in a comment in the returned content
out.println("<!-- SIRPAC TMP = " + m_SiRPACTmpDir);
out.println("GRAPH VIZ = " + m_GraphVizPath);
out.println("GRAPH LIB = " + m_GraphVizLibDir);
out.println("GRAPH FON = " + m_GraphVizFontDir + " -->");
out.println("Servlet initialization failed. A graph cannot be generated.");
return;
}
// The temporary directory
String tmpDir = m_SiRPACTmpDir;
// Must generate a unique file name that the DOT consumer
// will use
File dotFile = createTempFile(tmpDir, TMP_FILE_PREFIX, DOT_SUFFIX);
if (dotFile == null) {
out.println("Failed to create a temporary DOT file. A graph cannot be generated.");
return;
}
// Create a PrintWriter for the GraphViz consumer
FileWriter fw = new FileWriter(dotFile);
PrintWriter pw = new PrintWriter(fw);
// Run the parser using the DOT consumer to capture
// the output in a file
StringReader sr = new StringReader (rdf);
InputSource is = new InputSource (sr);
GraphVizDumpConsumer consumer = new GraphVizDumpConsumer(pw);
// Process any graph-related parameters in the request
processGraphParameters(req, consumer);
try {
m_sirpac.parse(is, consumer);
} catch (Exception e) {
out.println("An attempt to generate the graph data failed ("
+ e.getMessage() + ").");
pw.close();
dotFile.delete();
return;
}
// Must close the DOT input file so the GraphViz can
// open and read it
pw.close();
// Must generate a unique file name for the GIF file
// that will be created
File gifFile = createTempFile(tmpDir, TMP_FILE_PREFIX, GIF_SUFFIX);
if (gifFile == null) {
out.println("Failed to create a temporary GIF file. A graph cannot be generated.");
dotFile.delete();
return;
}
// Pass the DOT data file to the GraphViz dot program
// so it can create a GIF image of the data model
String dotFileName = dotFile.getAbsolutePath();
String gifFileName = gifFile.getAbsolutePath();
if (!generateGifFile(dotFileName, gifFileName)) {
out.println("An attempt to create a graph failed.");
dotFile.delete();
gifFile.delete();
return;
}
// Cleanup
dotFile.delete();
// NOTE: Cannot delete the GIF file here because its
// pathname is returned to the client
String imagePath = SERVLET_NAME +
TMP_DIR_SUFFIX + File.separator +
gifFile.getName();
if (gifFile.length() > 0)
out.println("<img src=\"" + imagePath + "\"/>");
else
out.println("The graph image file is empty.");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Search the given string for substring "key"
* and if it is found, replace it with string "replacement"
*
*@param input the input string
*@param key the string to search for
*@param replacement the string to replace all occurences of "key"
*@return if no substitutions are done, input is returned; otherwise
* a new string is returned.
*/
private String replaceString(String input, String key, String replacement) {
StringBuffer sb = new StringBuffer("");
StringTokenizer st = new StringTokenizer(input, key);
// Must handle the case where the input string begins with the key
if (input.startsWith(key))
sb = sb.append(replacement);
while (st.hasMoreTokens()) {
sb = sb.append(st.nextToken());
if (st.hasMoreTokens())
sb = sb.append(replacement);
}
if (sb.length() >= 1)
return sb.toString();
else
return input;
}
/*
* Print the document's header info
*
*@param out the servlet's output stream
*/
private void printDocumentHeader (ServletOutputStream out) {
try {
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\"");
out.println(" \"http://www.w3.org/TR/REC-html40/loose.dtd\">");
out.println("<HTML><HEAD>");
out.println("<TITLE>RDF creation</TITLE>");
out.println("<LINK HREF=\"rdf.css\" REL=\"stylesheet\">");
out.println("</HEAD>");
out.println("<BODY>");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Print the rdf listing
*
*@param out the servlet's output stream
*@param rdf the RDF code
*/
private void printListing (ServletOutputStream out, String rdf) {
try {
out.println("<hr title=\"original source\">");
out.println("<h3>The original RDF/XML document</h3>");
out.println("<pre>");
String s = replaceString(rdf, "<", "<");
StringTokenizer st = new StringTokenizer(s, "\n");
// Now output the RDF one line at a time with line numbers
int lineNum = 1;
while (st.hasMoreTokens()) {
out.print ("<a name=\"" + lineNum + "\">" + lineNum +
"</a>: " + st.nextToken());
lineNum++;
}
out.println("</pre>");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Print the header for the triple listing
*
*@param out the servlet's output stream
*/
private void printTripleHeader (ServletOutputStream out) {
try {
out.println("<hr title=\"triples\">");
out.println("<h3>Triples of the data model</h3>");
// The output for each triple will be pre-formatted
out.println("<pre>");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Print the footer info for the triple listing
*
*@param out the servlet's output stream
*/
private void printTripleFooter (ServletOutputStream out) {
try {
out.println("</pre>");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Print the document's footer info
*
*@param out the servlet's output stream
*@param rdf the RDF code
*/
private void printDocumentFooter (ServletOutputStream out, String rdf) {
try {
out.println("<hr title=\"Problem reporting\">");
out.println("<h3>Feedback</h3>");
out.println("<p>If you suspect that SiRPAC produced an error, please enter an explanation below and then press the <b>Submit problem report</b> button, to mail the report (and listing) to <i>" + MAIL_TO + "</i></p>");
out.println("<form enctype=\"text/plain\" method=\"post\" action=\"mailto:" + MAIL_TO + "\">");
out.println("<textarea cols=\"60\" rows=\"4\" name=\"report\"></textarea>");
out.println("<p><input type=\"hidden\" name=\"RDF\" value=\"<?xml version="1.0"?>");
// The listing is being passed as a parameter so the '<'
// and '"' characters must be replaced with < and ",
// respectively
String s1 = replaceString(rdf, "<", "<");
String s2 = replaceString(s1, "\"", """);
out.println(s2 + "\">");
out.println("<input type=\"submit\" value=\"Submit problem report\">");
out.println("</form>");
out.println("<hr><a href=\"/description\">Back</a> to main page.");
out.println("</BODY>");
out.println("</HTML>");
} catch (Exception e) {
System.err.println("Exception: " + e.getMessage());
}
}
/*
* Servlet's get info method
*/
public String getServletInfo () {
return "Servlet Wrapper for SiRPAC. This is revision " + REVISION;
}
/*
* Servlet's init method
*
*@param config the servlet's configuration object
*/
public void init(ServletConfig config) throws ServletException {
super.init (config);
m_sirpac = new SiRPAC();
m_errorHandler = new ErrorStore();
m_sirpac.setErrorHandler(m_errorHandler);
// Cache the parameters
m_SiRPACTmpDir = config.getInitParameter(SIRPAC_TMP_DIR);
// All of the Graph Viz paths extend from GRAPH_VIZ_ROOT
String GraphVizRoot = config.getInitParameter(GRAPH_VIZ_ROOT);
m_GraphVizPath = GraphVizRoot + "/" + config.getInitParameter(GRAPH_VIZ_PATH);
m_GraphVizFontDir = GraphVizRoot + "/" + config.getInitParameter(GRAPH_VIZ_FONT_DIR);
m_GraphVizLibDir = GraphVizRoot + "/" + config.getInitParameter(GRAPH_VIZ_LIB_DIR);
}
/*
* Servlet's destroy info method
*/
public void destroy () {
super.destroy ();
}
/*
* Servlet's doGet info method - NOT supported
*
*@param req the request
*@param res the response
*/
public void doGet (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
ServletOutputStream out = res.getOutputStream ();
res.setContentType ("text/html");
out.println ("<h1>GET is NOT supported!</h1>\n\n<p>Please send RDF through POST!</p>\n");
}
/*
* Servlet's doPost method
*
*@param req the request
*@param res the response
*/
public void doPost (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
ServletOutputStream out = res.getOutputStream ();
String sRDF = req.getParameter (POST_TEXT);
String sBags = req.getParameter (POST_BAG);
String sStreamMode = req.getParameter (POST_STREAM_MODE);
StringReader sr = new StringReader (sRDF);
InputSource is = new InputSource (sr);
boolean error = false;
SiRPACServletDumpConsumer consumer = new SiRPACServletDumpConsumer();
// Re-initialize the parser
m_sirpac = new SiRPAC();
m_errorHandler = new ErrorStore();
m_sirpac.setErrorHandler(m_errorHandler);
printDocumentHeader (out);
printListing (out, sRDF);
printTripleHeader (out);
try {
// Override the default triple output handler
consumer.setOutputStream(out);
// Toggle Bag handling - always false unless explicitly
// included in the request
m_sirpac.createBags (false);
if (sBags != null && sBags.equals ("on"))
m_sirpac.createBags (true);
// Set parser's streaming mode
if (sStreamMode != null && sStreamMode.equals ("on"))
m_sirpac.setStreamMode (false);
m_sirpac.parse(is, consumer);
generateGraph(out, sRDF, req);
} catch (SAXException e) {
error = true;
} catch (Exception e) {
error = true;
e.printStackTrace ();
}
printTripleFooter(out);
res.setContentType ("text/html");
if (error) {
out.println ("<h1>Errors during parsing</h1>\n");
out.println ("<pre>\n");
// Make the line number a link to the listing
out.println ("Fatal error: " + m_errorHandler.getErrorMessage());
out.println (" (Line number = " + "<a href=\"#" +
m_errorHandler.getLineNumber() + "\">" +
m_errorHandler.getLineNumber() + "</a>" +
", Column number = " +
m_errorHandler.getColumnNumber() + ")");
out.println ("</pre>\n\n");
}
printDocumentFooter(out, sRDF);
}
}
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