Example #1
0
 public byte[] toByteArray() {
   byte[] newBuf = null;
   if (!wrapped) {
     // We haven't wrapped yet so copy up to the current position
     newBuf = new byte[position];
     System.arraycopy(buf, 0, newBuf, 0, position);
   } else {
     // We'll have wrapped, so it's a two step process.
     // Copy everything following the position, then everything before
     newBuf = new byte[buf.length];
     // "position" is where we'd write next so it's the oldest byte.
     // So copy starting there for as many as are between there and the end.
     System.arraycopy(buf, position, newBuf, 0, (buf.length - position));
     // Now copy starting at 0, placing into the end of the last copy, up to position.
     System.arraycopy(buf, 0, newBuf, (buf.length - position), position);
   }
   return newBuf;
 }
Example #2
0
 /**
  * Returns the date in seconds.
  *
  * @return seconds
  */
 final BigDecimal seconds() {
   int z = tz;
   if (z == Short.MAX_VALUE) {
     // [CG] XQuery, DateTime: may be removed
     final long n = System.currentTimeMillis();
     z = Calendar.getInstance().getTimeZone().getOffset(n) / 60000;
   }
   return (sec == null ? BigDecimal.ZERO : sec)
       .add(BigDecimal.valueOf(Math.max(0, hou) * 3600 + Math.max(0, min) * 60 - z * 60));
 }
Example #3
0
  private static Interpreter getInterpreter(String contextId) throws EvalError {
    // Get the appropriate interpreter
    Interpreter i = null;
    boolean createdInterp = false;
    synchronized (interpreters) { // serialize two gets of the same name
      i = interpreters.get(contextId);
      if (i == null) {
        i = new Interpreter();
        interpreters.put(contextId, i);
        createdInterp = true;
      }
    }
    if (createdInterp) {
      Log.log("Created context: " + contextId + " (" + i + ")");

      // Now configure stdin and stdout to capture 10k of content
      // Store references to the circular buffers within the interpreter itself.
      // This provides a nice place to store them plus theoretically allows
      // advanced use from within the bsh environment.
      // On Windows print() outputs \r\n but in XQuery that's normalized to \n
      // so the 10k of Java buffer may produce less than 10k of content in XQuery!
      OutputStream circularOutput = new CircularByteArrayOutputStream(10240);
      PrintStream printOutput = new PrintStream(circularOutput);
      i.setOut(printOutput);
      i.set("mljamout", circularOutput);

      OutputStream circularError = new CircularByteArrayOutputStream(10240);
      PrintStream printError = new PrintStream(circularError);
      i.setErr(printError);
      i.set("mljamerr", circularError);

      // Capture the built-in System.out and System.err also.
      // (Commented out since System appears global, can't do per interpreter.)
      // i.set("mljamprintout", printOutput);
      // i.set("mljamprinterr", printError);
      // i.eval("System.setOut(mljamprintout);");
      // i.eval("System.setErr(mljamprinterr);");

      // Need to expose hexdecode() and base64decode() built-in functions
      i.eval("hexdecode(String s) { return com.xqdev.jam.MLJAM.hexDecode(s); }");
      i.eval("base64decode(String s) { return com.xqdev.jam.MLJAM.base64Decode(s); }");

      // Let's tell the context what its id is
      i.set("mljamid", contextId);
    }

    // Update the last accessed time, used for cleaning
    i.set("mljamlast", System.currentTimeMillis());

    // If it's been long enough, go snooping for stale contexts
    if (System.currentTimeMillis() > lastClean + CLEAN_INTERVAL) {
      Log.log("Initiated periodic scan for stale context objects");
      lastClean = System.currentTimeMillis();
      Iterator<Interpreter> itr = interpreters.values().iterator();
      while (itr.hasNext()) {
        Interpreter interp = itr.next();
        Long last = (Long) interp.get("mljamlast");
        if (System.currentTimeMillis() > last + STALE_TIMEOUT) {
          itr.remove();
          Log.log("Staled context: " + interp.get("mljamid") + " (" + interp + ")");
        } else if ((System.currentTimeMillis() > last + TEMP_STALE_TIMEOUT)
            && ("" + interp.get("mljamid")).startsWith("temp:")) {
          itr.remove();
          Log.log("Staled temp context: " + interp.get("mljamid") + " (" + interp + ")");
        }
      }
    }

    return i;
  }
Example #4
0
/**
 * TODO: Decide if we want to alter the jam:start() behavior so it connects to the server as a test.
 * This has the benefit that any server restart will HUP a client halfway through something because
 * the context will disappear rather than be implicitly recreated to an empty state. TODO: Consider
 * adding a feature so jam:start() can provide a user-specified stale-out duration for the context.
 */
public class MLJAM extends HttpServlet {

  private static HashMap<String, Interpreter> interpreters = new HashMap<String, Interpreter>();

  // Need to retire interpreters after some period of inactivity.
  // Temporary interpreters (those w/ client assigned names) expire faster
  private static long lastClean = System.currentTimeMillis();
  private static long CLEAN_INTERVAL = 5 * 60 * 1000; // five minutes
  private static long STALE_TIMEOUT = 60 * 60 * 1000; // one hour
  private static long TEMP_STALE_TIMEOUT = 60 * 60 * 1000; // ten minutes

  private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SZ");

  /*
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
  }
  */

  private static Interpreter getInterpreter(String contextId) throws EvalError {
    // Get the appropriate interpreter
    Interpreter i = null;
    boolean createdInterp = false;
    synchronized (interpreters) { // serialize two gets of the same name
      i = interpreters.get(contextId);
      if (i == null) {
        i = new Interpreter();
        interpreters.put(contextId, i);
        createdInterp = true;
      }
    }
    if (createdInterp) {
      Log.log("Created context: " + contextId + " (" + i + ")");

      // Now configure stdin and stdout to capture 10k of content
      // Store references to the circular buffers within the interpreter itself.
      // This provides a nice place to store them plus theoretically allows
      // advanced use from within the bsh environment.
      // On Windows print() outputs \r\n but in XQuery that's normalized to \n
      // so the 10k of Java buffer may produce less than 10k of content in XQuery!
      OutputStream circularOutput = new CircularByteArrayOutputStream(10240);
      PrintStream printOutput = new PrintStream(circularOutput);
      i.setOut(printOutput);
      i.set("mljamout", circularOutput);

      OutputStream circularError = new CircularByteArrayOutputStream(10240);
      PrintStream printError = new PrintStream(circularError);
      i.setErr(printError);
      i.set("mljamerr", circularError);

      // Capture the built-in System.out and System.err also.
      // (Commented out since System appears global, can't do per interpreter.)
      // i.set("mljamprintout", printOutput);
      // i.set("mljamprinterr", printError);
      // i.eval("System.setOut(mljamprintout);");
      // i.eval("System.setErr(mljamprinterr);");

      // Need to expose hexdecode() and base64decode() built-in functions
      i.eval("hexdecode(String s) { return com.xqdev.jam.MLJAM.hexDecode(s); }");
      i.eval("base64decode(String s) { return com.xqdev.jam.MLJAM.base64Decode(s); }");

      // Let's tell the context what its id is
      i.set("mljamid", contextId);
    }

    // Update the last accessed time, used for cleaning
    i.set("mljamlast", System.currentTimeMillis());

    // If it's been long enough, go snooping for stale contexts
    if (System.currentTimeMillis() > lastClean + CLEAN_INTERVAL) {
      Log.log("Initiated periodic scan for stale context objects");
      lastClean = System.currentTimeMillis();
      Iterator<Interpreter> itr = interpreters.values().iterator();
      while (itr.hasNext()) {
        Interpreter interp = itr.next();
        Long last = (Long) interp.get("mljamlast");
        if (System.currentTimeMillis() > last + STALE_TIMEOUT) {
          itr.remove();
          Log.log("Staled context: " + interp.get("mljamid") + " (" + interp + ")");
        } else if ((System.currentTimeMillis() > last + TEMP_STALE_TIMEOUT)
            && ("" + interp.get("mljamid")).startsWith("temp:")) {
          itr.remove();
          Log.log("Staled temp context: " + interp.get("mljamid") + " (" + interp + ")");
        }
      }
    }

    return i;
  }

  private static void endInterpreter(String contextId) throws EvalError {
    Interpreter i = interpreters.get(contextId);
    if (i == null) return;
    i.eval("clear();"); // can't hurt to tell bsh to clean up internally
    interpreters.remove(contextId); // now wait for GC
    Log.log("Destroyed context: " + contextId + " (" + i + ")");
  }

  private static String getBody(HttpServletRequest req) {
    try {
      // Try reading the post body using characters.
      // This might throw an exception if something on the
      // server side already called getInputStream().
      // In that case we'll pull as bytes.
      Reader reader = null;
      try {
        reader = new BufferedReader(req.getReader());
      } catch (IOException e) {
        reader = new BufferedReader(new InputStreamReader(req.getInputStream(), "UTF-8"));
      }

      StringBuffer sbuf = new StringBuffer();
      char[] cbuf = new char[4096];
      int count = 0;
      while ((count = reader.read(cbuf)) != -1) {
        sbuf.append(cbuf, 0, count);
      }
      return sbuf.toString();
    } catch (IOException e2) {
      throw new ServerProblemException("IOException in reading POST body: " + e2.getMessage());
    }
  }

  protected void doGet(HttpServletRequest req, HttpServletResponse res)
      throws ServletException, IOException {
    doPost(req, res);
  }

  protected void doPost(HttpServletRequest req, HttpServletResponse res)
      throws ServletException, IOException {
    try {
      // A good request looks like /mljam/contextid/verb?name=varname
      // The extra path info includes the context id and verb
      String extra = req.getPathInfo(); // "/contextid/verb"
      if (extra == null || extra.equals("")) {
        throw new ClientProblemException(
            "Request requires a context id and verb in its extra path info");
      }
      String[] parts = extra.split("/"); // { "", "contextid", "verb" }
      if (parts.length < 2) {
        throw new ClientProblemException(
            "Request requires a context id and verb in its extra path info");
      } else if (parts.length < 3) {
        throw new ClientProblemException("Request requires a verb in its extra path info");
      }

      String contextId = parts[1];
      String verb = parts[2];
      String method = req.getMethod();

      if (method.equalsIgnoreCase("get")) {

        // We have three GET verbs: get, get-stdout, get-stderr.
        // These are all idempotent, while the POST verbs aren't.  The get
        // verb accept a "name" query string parameter.  The get verb returns
        // either XQuery to evaluate (indicated by x-marklogic/xquery content type)
        // or a raw binary (indicated by an application/binary-encoded content type).

        if (verb.equalsIgnoreCase("get")) {
          String name = req.getParameter("name");
          if (name == null || name.equals("")) {
            throw new ClientProblemException("The get verb requires a name parameter");
          }
          Interpreter i = getInterpreter(contextId);
          Object o = i.get(name);
          if (o instanceof byte[]) {
            sendBinaryResponse(res, (byte[]) o);
          } else if (o instanceof String) {
            sendStringResponse(res, (String) o);
          } else {
            sendXQueryResponse(res, o);
          }
        } else if (verb.equalsIgnoreCase("get-stdout")) {
          Interpreter i = getInterpreter(contextId);
          i.getOut().flush();
          CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamout");
          if (circ != null) {
            sendStringResponse(res, circ.toString());
            circ.reset();
          } else {
            throw new ServerProblemException("Could not fetch mljamout from interpreter context");
          }
        } else if (verb.equalsIgnoreCase("get-stderr")) {
          Interpreter i = getInterpreter(contextId);
          i.getErr().flush();
          CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamerr");
          if (circ != null) {
            sendStringResponse(res, circ.toString());
            circ.reset();
          } else {
            throw new ServerProblemException("Could not fetch mljamerr from interpreter context");
          }
        } else {
          throw new ClientProblemException("Unrecognized GET verb: " + verb);
        }
      } else if (method.equalsIgnoreCase("post")) {
        // We have six POST verbs: eval, unset, end, source, set-string, and set-binary.
        // These are POST verbs because they aren't idempotent.
        // The set-string, set-binary, unset, and source verbs accept a "name"
        // query string parameter.  The set-string and set-binary verbs accept
        // a value in their post body.  The eval verb accepts code in its post body.

        if (verb.equalsIgnoreCase("set-string")) {
          String name = req.getParameter("name");
          if (name == null || name.equals("")) {
            throw new ClientProblemException("The set-string verb requires a name parameter");
          }
          String body = getBody(req); // a value of "" is legit
          Interpreter i = getInterpreter(contextId);
          i.unset(name);
          i.set(name, body);
          sendNoResponse(res);
        } else if (verb.equalsIgnoreCase("set-binary")) {
          String name = req.getParameter("name");
          if (name == null || name.equals("")) {
            throw new ClientProblemException("The set-binary verb requires a name parameter");
          }
          String body = getBody(req); // a value of "" is legit
          byte[] bodyBytes = hexDecode(body); // later could do this streaming for speed
          Interpreter i = getInterpreter(contextId);
          i.unset(name);
          i.set(name, bodyBytes);
          sendNoResponse(res);
        } else if (verb.equalsIgnoreCase("eval")) {
          String body = getBody(req);
          if (body == null || body.equals("")) {
            throw new ClientProblemException(
                "The eval verb requires a post body containing code to eval");
          }
          Interpreter i = getInterpreter(contextId);
          i.eval(body);
          sendNoResponse(res);
        } else if (verb.equalsIgnoreCase("eval-get")) {
          String body = getBody(req);
          if (body == null || body.equals("")) {
            throw new ClientProblemException(
                "The eval-get verb requires a post body containing code to eval");
          }
          Interpreter i = getInterpreter(contextId);
          Object o = i.eval(body);
          if (o instanceof byte[]) {
            sendBinaryResponse(res, (byte[]) o);
          } else if (o instanceof String) {
            sendStringResponse(res, (String) o);
          } else {
            sendXQueryResponse(res, o);
          }
        } else if (verb.equalsIgnoreCase("unset")) {
          String name = req.getParameter("name");
          if (name == null || name.equals("")) {
            throw new ClientProblemException("The unset verb requires a name parameter");
          }
          Interpreter i = getInterpreter(contextId);
          i.unset(name);
          sendNoResponse(res);
        } else if (verb.equalsIgnoreCase("end")) {
          endInterpreter(contextId);
          sendNoResponse(res);
        } else if (verb.equalsIgnoreCase("source")) {
          String name = req.getParameter("name");
          if (name == null || name.equals("")) {
            throw new ClientProblemException("The source verb requires a name parameter");
          }
          Interpreter i = getInterpreter(contextId);
          i.source(name);
          sendNoResponse(res);
        } else {
          throw new ClientProblemException("Unrecognized POST verb: " + verb);
        }
      }
    } catch (TargetError e) {
      Throwable target = e.getTarget();
      Log.log(e);
      Log.log("Target: " + target);
      sendServerProblemResponse(
          res,
          target.getClass().getName()
              + ": "
              + target.getMessage()
              + " when executing Java code: "
              + e.getErrorText()); // include full trace?
    } catch (EvalError e) {
      Log.log(e);
      sendServerProblemResponse(
          res, e.getClass().getName() + ": " + e.getMessage()); // include full trace?
    } catch (ClientProblemException e) {
      Log.log(e);
      sendClientProblemResponse(res, e.getMessage());
    } catch (ServerProblemException e) {
      Log.log(e);
      sendServerProblemResponse(res, e.getMessage());
    }
  }

  private static String escapeSingleQuotes(String s) {
    return s.replaceAll("'", "''");
  }

  public static byte[] hexDecode(String s) {
    try {
      return Hex.decodeHex(s.toCharArray());
    } catch (DecoderException e) {
      throw new ClientProblemException(
          "Hex content is not valid hex: " + e.getMessage() + ": " + s);
    }
  }

  private static String hexEncode(byte[] bytes) {
    return new String(Hex.encodeHex(bytes));
  }

  public static byte[] base64Decode(String s) {
    try {
      return Base64.decodeBase64(s.getBytes("ISO-8859-1"));
    } catch (UnsupportedEncodingException e) {
      throw new ServerProblemException("Server does not recognize ISO-8859-1 encoding");
    }
  }

  private static void sendClientProblemResponse(HttpServletResponse res, String s)
      throws IOException {
    // Commenting out the status code because we want the client to eval the error() call
    // res.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    if (s != null && s.length() > 4096) { // Cap super long errors
      s = s.substring(0, 2048) + " ...[trimmed]... " + s.substring(s.length() - 2048);
    }
    res.setContentType("x-marklogic/xquery; charset=UTF-8");
    Writer writer = res.getWriter();
    writer.write("error('" + escapeSingleQuotes(s) + "')");
    writer.flush();
  }

  private static void sendServerProblemResponse(HttpServletResponse res, String s)
      throws IOException {
    // Commenting out the status code because we want the client to eval the error() call
    // res.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
    res.setContentType("x-marklogic/xquery; charset=UTF-8");
    if (s != null && s.length() > 4096) { // Cap super long errors
      s = s.substring(0, 2048) + " ...[trimmed]... " + s.substring(s.length() - 2048);
    }
    Writer writer = res.getWriter();
    writer.write("error('" + escapeSingleQuotes(s) + "')");
    writer.flush();
  }

  private static void sendNoResponse(HttpServletResponse res) {
    res.setStatus(HttpServletResponse.SC_NO_CONTENT);
  }

  private static void sendBinaryResponse(HttpServletResponse res, byte[] bytes) throws IOException {
    res.setContentType("application/binary-encoded");
    OutputStream out = res.getOutputStream(); // care to handle errors later?
    out.write(bytes);
    out.flush();
  }

  private static void sendStringResponse(HttpServletResponse res, String s) throws IOException {
    res.setContentType("text/plain; charset=UTF-8");
    Writer w = res.getWriter();
    w.write(s);
    w.flush();
  }

  private static void sendXQueryResponse(HttpServletResponse res, Object o) throws IOException {
    // Make sure to leave the status code alone.  It defaults to 200, but sometimes
    // callers of this method will have set it to a custom code.
    res.setContentType("x-marklogic/xquery; charset=UTF-8");
    // res.setContentType("text/plain");
    Writer writer = res.getWriter(); // care to handle errors later?

    if (o == null) {
      writer.write("()");
    } else if (o instanceof byte[]) {
      writer.write("binary {'");
      writer.write(hexEncode((byte[]) o));
      writer.write("'}");
    } else if (o instanceof Object[]) {
      Object[] arr = (Object[]) o;
      writer.write("(");
      for (int i = 0; i < arr.length; i++) {
        sendXQueryResponse(res, arr[i]);
        if (i + 1 < arr.length) writer.write(", ");
      }
      writer.write(")");
    } else if (o instanceof String) {
      writer.write("'");
      writer.write(escapeSingleQuotes(o.toString()));
      writer.write("'");
    } else if (o instanceof Integer) {
      writer.write("xs:int(");
      writer.write(o.toString());
      writer.write(")");
    } else if (o instanceof Long) {
      writer.write("xs:integer(");
      writer.write(o.toString());
      writer.write(")");
    } else if (o instanceof Float) {
      Float flt = (Float) o;
      writer.write("xs:float(");
      if (flt.equals(Float.POSITIVE_INFINITY)) {
        writer.write("'INF'");
      } else if (flt.equals(Float.NEGATIVE_INFINITY)) {
        writer.write("'-INF'");
      } else if (flt.equals(Float.NaN)) {
        writer.write("fn:number(())"); // poor man's way to write NaN
      } else {
        writer.write(o.toString());
      }
      writer.write(")");
    } else if (o instanceof Double) {
      Double dbl = (Double) o;
      writer.write("xs:double(");
      if (dbl.equals(Double.POSITIVE_INFINITY)) {
        writer.write("'INF'");
      } else if (dbl.equals(Double.NEGATIVE_INFINITY)) {
        writer.write("'-INF'");
      } else if (dbl.equals(Double.NaN)) {
        writer.write("fn:number(())"); // poor man's way to write NaN
      } else {
        writer.write(o.toString());
      }
      writer.write(")");
    } else if (o instanceof Boolean) {
      writer.write("xs:boolean('");
      writer.write(o.toString());
      writer.write("')");
    } else if (o instanceof BigDecimal) {
      writer.write("xs:decimal(");
      writer.write(o.toString());
      writer.write(")");
    } else if (o instanceof Date) {
      // We want something like: 2006-04-30T01:28:30.499-07:00
      // We format to get:       2006-04-30T01:28:30.499-0700
      // Then we add in the colon
      writer.write("xs:dateTime('");
      String d = dateFormat.format((Date) o);
      writer.write(d.substring(0, d.length() - 2));
      writer.write(":");
      writer.write(d.substring(d.length() - 2));
      writer.write("')");
    } else if (o instanceof XMLGregorianCalendar) {
      XMLGregorianCalendar greg = (XMLGregorianCalendar) o;
      QName type = greg.getXMLSchemaType();
      if (type.equals(DatatypeConstants.DATETIME)) {
        writer.write("xs:dateTime('");
      } else if (type.equals(DatatypeConstants.DATE)) {
        writer.write("xs:date('");
      } else if (type.equals(DatatypeConstants.TIME)) {
        writer.write("xs:time('");
      } else if (type.equals(DatatypeConstants.GYEARMONTH)) {
        writer.write("xs:gYearMonth('");
      } else if (type.equals(DatatypeConstants.GMONTHDAY)) {
        writer.write("xs:gMonthDay('");
      } else if (type.equals(DatatypeConstants.GYEAR)) {
        writer.write("xs:gYear('");
      } else if (type.equals(DatatypeConstants.GMONTH)) {
        writer.write("xs:gMonth('");
      } else if (type.equals(DatatypeConstants.GDAY)) {
        writer.write("xs:gDay('");
      }
      writer.write(greg.toXMLFormat());
      writer.write("')");
    } else if (o instanceof Duration) {
      Duration dur = (Duration) o;
      /*
      // The following fails on Xerces
      QName type = dur.getXMLSchemaType();
      if (type.equals(DatatypeConstants.DURATION)) {
        writer.write("xs:duration('");
      }
      else if (type.equals(DatatypeConstants.DURATION_DAYTIME)) {
        writer.write("xdt:dayTimeDuration('");
      }
      else if (type.equals(DatatypeConstants.DURATION_YEARMONTH)) {
        writer.write("xdt:yearMonthDuration('");
      }
      */
      // If no years or months, must be DURATION_DAYTIME
      if (dur.getYears() == 0 && dur.getMonths() == 0) {
        writer.write("xdt:dayTimeDuration('");
      }
      // If has years or months but nothing else, must be DURATION_YEARMONTH
      else if (dur.getDays() == 0
          && dur.getHours() == 0
          && dur.getMinutes() == 0
          && dur.getSeconds() == 0) {
        writer.write("xdt:yearMonthDuration('");
      } else {
        writer.write("xs:duration('");
      }
      writer.write(dur.toString());
      writer.write("')");
    } else if (o instanceof org.jdom.Element) {
      org.jdom.Element elt = (org.jdom.Element) o;
      writer.write("xdmp:unquote('");
      // Because "&lt;" in XQuery is the same as "<" I need to double escape any ampersands
      writer.write(
          new org.jdom.output.XMLOutputter()
              .outputString(elt)
              .replaceAll("&", "&amp;")
              .replaceAll("'", "''"));
      writer.write("')/*"); // make sure to return the root elt
    } else if (o instanceof org.jdom.Document) {
      org.jdom.Document doc = (org.jdom.Document) o;
      writer.write("xdmp:unquote('");
      writer.write(
          new org.jdom.output.XMLOutputter()
              .outputString(doc)
              .replaceAll("&", "&amp;")
              .replaceAll("'", "''"));
      writer.write("')");
    } else if (o instanceof org.jdom.Text) {
      org.jdom.Text text = (org.jdom.Text) o;
      writer.write("text {'");
      writer.write(escapeSingleQuotes(text.getText()));
      writer.write("'}");
    } else if (o instanceof org.jdom.Attribute) {
      // <fake xmlns:pref="http://uri.com" pref:attrname="attrvalue"/>/@*:attrname
      // <fake xmlns="http://uri.com" attrname="attrvalue"/>/@*:attrname
      org.jdom.Attribute attr = (org.jdom.Attribute) o;
      writer.write("<fake xmlns");
      if ("".equals(attr.getNamespacePrefix())) {
        writer.write("=\"");
      } else {
        writer.write(":" + attr.getNamespacePrefix() + "=\"");
      }
      writer.write(attr.getNamespaceURI());
      writer.write("\" ");
      writer.write(attr.getQualifiedName());
      writer.write("=\"");
      writer.write(escapeSingleQuotes(attr.getValue()));
      writer.write("\"/>/@*:");
      writer.write(attr.getName());
    } else if (o instanceof org.jdom.Comment) {
      org.jdom.Comment com = (org.jdom.Comment) o;
      writer.write("comment {'");
      writer.write(escapeSingleQuotes(com.getText()));
      writer.write("'}");
    } else if (o instanceof org.jdom.ProcessingInstruction) {
      org.jdom.ProcessingInstruction pi = (org.jdom.ProcessingInstruction) o;
      writer.write("processing-instruction ");
      writer.write(pi.getTarget());
      writer.write(" {'");
      writer.write(escapeSingleQuotes(pi.getData()));
      writer.write("'}");
    } else if (o instanceof QName) {
      QName q = (QName) o;
      writer.write("fn:expanded-QName('");
      writer.write(escapeSingleQuotes(q.getNamespaceURI()));
      writer.write("','");
      writer.write(q.getLocalPart());
      writer.write("')");
    } else {
      writer.write(
          "error('XQuery tried to retrieve unsupported type: " + o.getClass().getName() + "')");
    }

    writer.flush();
  }
}