Exemplo n.º 1
0
  public void init() throws javax.servlet.ServletException {
    super.init();

    org.slf4j.Logger logServerStartup = org.slf4j.LoggerFactory.getLogger("serverStartup");
    logServerStartup.info(
        getClass().getName() + " initialization start - " + UsageLog.setupNonRequestContext());

    this.ascLimit = ThreddsConfig.getInt("Opendap.ascLimit", ascLimit);
    this.binLimit = ThreddsConfig.getInt("Opendap.binLimit", binLimit);

    this.odapVersionString = ThreddsConfig.get("Opendap.serverVersion", odapVersionString);
    logServerStartup.info(
        getClass().getName()
            + " version= "
            + odapVersionString
            + " ascLimit = "
            + ascLimit
            + " binLimit = "
            + binLimit);

    // debugging actions
    makeDebugActions();

    logServerStartup.info(
        getClass().getName()
            + " initialization done - "
            + UsageLog.closingMessageNonRequestContext());
  }
Exemplo n.º 2
0
/**
 * THREDDS opendap server.
 *
 * @author jcaron
 * @author Nathan David Potter
 * @since Apr 27, 2009 (branched)
 */
public class OpendapServlet extends AbstractServlet {
  static final String DEFAULTCONTEXTPATH = "/thredds";
  static final String GDATASET = "guarded_dataset";
  private static org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(OpendapServlet.class);

  private boolean allowSessions = false;
  private boolean allowDeflate = false; // handled by Tomcat

  private String odapVersionString = "opendap/3.7";

  private URI baseURI = null;

  private int ascLimit = 50;
  private int binLimit = 500;

  private boolean debugSession = false;

  public String getDefaultContextPath() {
    return DEFAULTCONTEXTPATH;
  }

  public void init() throws javax.servlet.ServletException {
    super.init();

    org.slf4j.Logger logServerStartup = org.slf4j.LoggerFactory.getLogger("serverStartup");
    logServerStartup.info(
        getClass().getName() + " initialization start - " + UsageLog.setupNonRequestContext());

    this.ascLimit = ThreddsConfig.getInt("Opendap.ascLimit", ascLimit);
    this.binLimit = ThreddsConfig.getInt("Opendap.binLimit", binLimit);

    this.odapVersionString = ThreddsConfig.get("Opendap.serverVersion", odapVersionString);
    logServerStartup.info(
        getClass().getName()
            + " version= "
            + odapVersionString
            + " ascLimit = "
            + ascLimit
            + " binLimit = "
            + binLimit);

    // debugging actions
    makeDebugActions();

    logServerStartup.info(
        getClass().getName()
            + " initialization done - "
            + UsageLog.closingMessageNonRequestContext());
  }

  public String getServerVersion() {
    return this.odapVersionString;
  }

  // Servlets that support HTTP GET requests and can quickly determine their last modification time
  // should
  // override this method. This makes browser and proxy caches work more effectively, reducing the
  // load on
  // server and network resources.
  protected long getLastModified(HttpServletRequest req) {
    String query = req.getQueryString();
    if (query != null) return -1;

    String path = req.getPathInfo();
    if (path == null) return -1;

    if (path.endsWith(".asc")) path = path.substring(0, path.length() - 4);
    else if (path.endsWith(".ascii")) path = path.substring(0, path.length() - 6);
    else if (path.endsWith(".das")) path = path.substring(0, path.length() - 4);
    else if (path.endsWith(".dds")) path = path.substring(0, path.length() - 4);
    else if (path.endsWith(".ddx")) path = path.substring(0, path.length() - 4);
    else if (path.endsWith(".dods")) path = path.substring(0, path.length() - 5);
    else if (path.endsWith(".html")) path = path.substring(0, path.length() - 5);
    else if (path.endsWith(".info")) path = path.substring(0, path.length() - 5);
    else if (path.endsWith(".opendap")) path = path.substring(0, path.length() - 5);
    else return -1;

    // if (null != DatasetHandler.findResourceControl( path)) return -1; // LOOK weird Firefox
    // beahviour?

    File file = DataRootHandler.getInstance().getCrawlableDatasetAsFile(path);
    if ((file != null) && file.exists()) return file.lastModified();

    return -1;
  }

  /////////////////////////////////////////////////////////////////////////////

  public void doGet(HttpServletRequest request, HttpServletResponse response) {
    log.info("doGet(): " + UsageLog.setupRequestContext(request));
    // System.out.printf("opendap doGet: req=%s%n%s%n", ServletUtil.getRequest(request),
    // ServletUtil.showRequestDetail(this, request));

    String path = null;

    ReqState rs = getRequestState(request, response);

    try {
      path = request.getPathInfo();
      log.debug("doGet path={}", path);

      if (thredds.servlet.Debug.isSet("showRequestDetail"))
        log.debug(ServletUtil.showRequestDetail(this, request));

      if (path == null) {
        log.info(
            "doGet(): "
                + UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_NOT_FOUND, -1));
        response.sendError(HttpServletResponse.SC_NOT_FOUND);
        return;
      }

      if (baseURI == null) { // first time, set baseURI
        URI reqURI = ServletUtil.getRequestURI(request);
        // Build base URI from request (rather than hard-coding "/thredds/dodsC/").
        String baseUriString = request.getContextPath() + request.getServletPath() + "/";
        baseURI = reqURI.resolve(baseUriString);
        log.debug("doGet(): baseURI was set = {}", baseURI);
      }

      if (path.endsWith("latest.xml")) {
        DataRootHandler.getInstance().processReqForLatestDataset(this, request, response);
        return;
      }

      // Redirect all catalog requests at the root level.
      if (path.equals("/") || path.equals("/catalog.html") || path.equals("/catalog.xml")) {
        ServletUtil.sendPermanentRedirect(ServletUtil.getContextPath() + path, request, response);
        return;
      }

      // Make sure catalog requests match a dataRoot before trying to handle.
      if (path.endsWith("/") || path.endsWith("/catalog.html") || path.endsWith("/catalog.xml")) {
        if (!DataRootHandler.getInstance().hasDataRootMatch(path)) {
          log.info(
              "doGet(): "
                  + UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_NOT_FOUND, -1));
          response.sendError(HttpServletResponse.SC_NOT_FOUND);
          return;
        }

        if (!DataRootHandler.getInstance().processReqForCatalog(request, response))
          log.error(
              "doGet(): "
                  + UsageLog.closingMessageForRequestContext(
                      ServletUtil.STATUS_FORWARD_FAILURE, -1));

        return;
      }

      if (rs != null) {
        String dataSet = rs.getDataSet();
        String requestSuffix = rs.getRequestSuffix();

        if ((dataSet == null) || dataSet.equals("/") || dataSet.equals("")) {
          doGetDIR(rs);
        } else if (requestSuffix.equalsIgnoreCase("blob")) {
          doGetBLOB(rs);
        } else if (requestSuffix.equalsIgnoreCase("close")) {
          doClose(rs);
        } else if (requestSuffix.equalsIgnoreCase("dds")) {
          doGetDDS(rs);
        } else if (requestSuffix.equalsIgnoreCase("das")) {
          doGetDAS(rs);
        } else if (requestSuffix.equalsIgnoreCase("ddx")) {
          doGetDDX(rs);
        } else if (requestSuffix.equalsIgnoreCase("dods")) {
          doGetDAP2Data(rs);
        } else if (requestSuffix.equalsIgnoreCase("asc")
            || requestSuffix.equalsIgnoreCase("ascii")) {
          doGetASC(rs);
        } else if (requestSuffix.equalsIgnoreCase("info")) {
          doGetINFO(rs);
        } else if (requestSuffix.equalsIgnoreCase("html")
            || requestSuffix.equalsIgnoreCase("htm")) {
          doGetHTML(rs);
        } else if (requestSuffix.equalsIgnoreCase("ver")
            || requestSuffix.equalsIgnoreCase("version")
            || dataSet.equalsIgnoreCase("/version")
            || dataSet.equalsIgnoreCase("/version/")) {
          doGetVER(rs);
        } else if (dataSet.equalsIgnoreCase("/help")
            || dataSet.equalsIgnoreCase("/help/")
            || dataSet.equalsIgnoreCase("/" + requestSuffix)
            || requestSuffix.equalsIgnoreCase("help")) {
          doGetHELP(rs);
        } else {
          sendErrorResponse(response, HttpServletResponse.SC_BAD_REQUEST, "Unrecognized request");
          return;
        }

      } else {
        sendErrorResponse(response, HttpServletResponse.SC_BAD_REQUEST, "Unrecognized request");
        return;
      }

      log.info(UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_OK, -1));

      // plain ol' 404
    } catch (FileNotFoundException e) {
      sendErrorResponse(response, HttpServletResponse.SC_NOT_FOUND, e.getMessage());

      // DAP2Exception bad url
    } catch (BadURLException e) {
      log.info(UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_BAD_REQUEST, -1));
      response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
      dap2ExceptionHandler(e, rs);

      // all other DAP2Exception
    } catch (DAP2Exception de) {
      int status =
          (de.getErrorCode() == DAP2Exception.NO_SUCH_FILE)
              ? HttpServletResponse.SC_NOT_FOUND
              : HttpServletResponse.SC_BAD_REQUEST;
      if ((de.getErrorCode() != DAP2Exception.NO_SUCH_FILE) && (de.getErrorMessage() != null))
        log.debug(de.getErrorMessage());
      log.info(UsageLog.closingMessageForRequestContext(status, -1));
      response.setStatus(status);
      dap2ExceptionHandler(de, rs);

      // parsing, usually the CE
    } catch (ParseException pe) {
      log.info(UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_BAD_REQUEST, -1));
      response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
      parseExceptionHandler(pe, response);

      // 403 - request too big
    } catch (UnsupportedOperationException e) {
      sendErrorResponse(response, HttpServletResponse.SC_FORBIDDEN, e.getMessage());

    } catch (java.net.SocketException e) {
      log.info("SocketException: " + e.getMessage(), e);
      log.info(UsageLog.closingMessageForRequestContext(ServletUtil.STATUS_CLIENT_ABORT, -1));

    } catch (IOException e) {
      String eName =
          e.getClass().getName(); // dont want compile time dependency on ClientAbortException
      if (eName.equals("org.apache.catalina.connector.ClientAbortException")) {
        log.debug("ClientAbortException: " + e.getMessage());
        log.info(UsageLog.closingMessageForRequestContext(ServletUtil.STATUS_CLIENT_ABORT, -1));
        return;
      }

      log.error("path= " + path, e);
      sendErrorResponse(response, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());

      // everything else
    } catch (Throwable t) {
      log.error("path= " + path, t);
      t.printStackTrace();
      sendErrorResponse(response, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, t.getMessage());
    }
  }

  public void doGetASC(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (ds == null) return;

      response.setHeader("XDODS-Server", getServerVersion());
      response.setContentType("text/plain");
      response.setHeader("Content-Description", "dods-ascii");

      log.debug(
          "Sending OPeNDAP ASCII Data For: " + rs + "  CE: '" + rs.getConstraintExpression() + "'");

      ServerDDS dds = ds.getDDS();
      CEEvaluator ce = new CEEvaluator(dds);
      ce.parseConstraint(rs);
      checkSize(dds, true);

      PrintWriter pw = new PrintWriter(response.getOutputStream());
      dds.printConstrained(pw);
      pw.println("---------------------------------------------");

      AsciiWriter writer = new AsciiWriter(); // could be static
      writer.toASCII(pw, dds, ds);

      // the way that getDAP2Data works
      // DataOutputStream sink = new DataOutputStream(bOut);
      // ce.send(myDDS.getName(), sink, ds);

      pw.flush();

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetDAS(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (ds == null) return;

      response.setContentType("text/plain");
      response.setHeader("XDODS-Server", getServerVersion());
      response.setHeader("Content-Description", "dods-das");

      OutputStream Out = new BufferedOutputStream(response.getOutputStream());

      DAS myDAS = ds.getDAS();
      myDAS.print(Out);

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetDDS(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (null == ds) return;

      response.setContentType("text/plain");
      response.setHeader("XDODS-Server", getServerVersion());
      response.setHeader("Content-Description", "dods-dds");

      OutputStream out = new BufferedOutputStream(response.getOutputStream());
      ServerDDS myDDS = ds.getDDS();

      if (rs.getConstraintExpression().equals("")) { // No Constraint Expression?
        // Send the whole DDS
        myDDS.print(out);
        out.flush();

      } else { // Otherwise, send the constrained DDS
        // Instantiate the CEEvaluator and parse the constraint expression
        CEEvaluator ce = new CEEvaluator(myDDS);
        ce.parseConstraint(rs);

        // Send the constrained DDS back to the client
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(out));
        myDDS.printConstrained(pw);
        pw.flush();
      }

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetDDX(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (null == ds) return;

      response.setContentType("text/plain");
      response.setHeader("XDODS-Server", getServerVersion());
      response.setHeader("Content-Description", "dods-ddx");

      OutputStream out = new BufferedOutputStream(response.getOutputStream());

      ServerDDS myDDS = ds.getDDS();
      myDDS.ingestDAS(ds.getDAS());

      if (rs.getConstraintExpression().equals("")) { // No Constraint Expression?
        // Send the whole DDS
        myDDS.printXML(out);
        out.flush();
      } else { // Otherwise, send the constrained DDS

        // Instantiate the CEEvaluator and parse the constraint expression
        CEEvaluator ce = new CEEvaluator(myDDS);
        ce.parseConstraint(rs);

        // Send the constrained DDS back to the client
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(out));
        myDDS.printConstrainedXML(pw);
        pw.flush();
      }

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetBLOB(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (null == ds) return;

      response.setContentType("application/octet-stream");
      response.setHeader("XDODS-Server", getServerVersion());
      response.setHeader("Content-Description", "dods-blob");

      ServletOutputStream sOut = response.getOutputStream();
      OutputStream bOut;
      DeflaterOutputStream dOut = null;
      if (rs.getAcceptsCompressed() && allowDeflate) {
        response.setHeader("Content-Encoding", "deflate");
        dOut = new DeflaterOutputStream(sOut);
        bOut = new BufferedOutputStream(dOut);
      } else {
        bOut = new BufferedOutputStream(sOut);
      }

      ServerDDS myDDS = ds.getDDS();
      CEEvaluator ce = new CEEvaluator(myDDS);
      ce.parseConstraint(rs);
      checkSize(myDDS, false);

      // Send the binary data back to the client
      DataOutputStream sink = new DataOutputStream(bOut);
      ce.send(myDDS.getEncodedName(), sink, ds);
      sink.flush();

      // Finish up sending the compressed stuff, but don't
      // close the stream (who knows what the Servlet may expect!)
      if (null != dOut) dOut.finish();
      bOut.flush();

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  private void doClose(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();
    HttpServletRequest request = rs.getRequest();
    String reqPath = rs.getDataSet();
    HttpSession session = request.getSession();
    session.removeAttribute(reqPath); // work done in the listener

    response.setHeader("XDODS-Server", getServerVersion()); // needed by client

    /* if (path.endsWith(".close")) {
      closeSession(request, response);
      response.setContentLength(0);
      log.info("doGet(): " + UsageLog.closingMessageForRequestContext(HttpServletResponse.SC_OK, 0));
      return;

    }

    // so we need to worry about deleting sessions?
    session.invalidate();  */
  }

  public void doGetDAP2Data(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (null == ds) return;

      response.setContentType("application/octet-stream");
      response.setHeader("XDODS-Server", getServerVersion());
      response.setHeader("Content-Description", "dods-data");

      ServletOutputStream sOut = response.getOutputStream();
      OutputStream bOut;
      DeflaterOutputStream dOut = null;
      if (rs.getAcceptsCompressed() && allowDeflate) {
        response.setHeader("Content-Encoding", "deflate");
        dOut = new DeflaterOutputStream(sOut);
        bOut = new BufferedOutputStream(dOut);

      } else {
        bOut = new BufferedOutputStream(sOut);
      }

      ServerDDS myDDS = ds.getDDS();
      CEEvaluator ce = new CEEvaluator(myDDS);
      ce.parseConstraint(rs);
      checkSize(myDDS, false);

      // Send the constrained DDS back to the client
      PrintWriter pw = new PrintWriter(new OutputStreamWriter(bOut));
      myDDS.printConstrained(pw);

      // Send the Data delimiter back to the client
      pw.flush();
      bOut.write("\nData:\n".getBytes());
      bOut.flush();

      // Send the binary data back to the client
      DataOutputStream sink = new DataOutputStream(bOut);
      ce.send(myDDS.getEncodedName(), sink, ds);
      sink.flush();

      // Finish up sending the compressed stuff, but don't
      // close the stream (who knows what the Servlet may expect!)
      if (null != dOut) dOut.finish();
      bOut.flush();

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetVER(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    response.setContentType("text/plain");
    response.setHeader("XDODS-Server", getServerVersion());
    response.setHeader("Content-Description", "dods-version");

    PrintWriter pw = new PrintWriter(new OutputStreamWriter(response.getOutputStream()));

    pw.println("Server Version: " + getServerVersion());
    pw.flush();
  }

  public void doGetHELP(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();

    response.setContentType("text/html");
    response.setHeader("XDODS-Server", getServerVersion());
    response.setHeader("Content-Description", "dods-help");

    PrintWriter pw = new PrintWriter(new OutputStreamWriter(response.getOutputStream()));
    printHelpPage(pw);
    pw.flush();
  }

  public void doGetDIR(ReqState rs) throws Exception {
    // rather dangerous here, since you can go into an infinite loop
    // so we're going to insist that there's  no suffix
    HttpServletResponse response = rs.getResponse();
    HttpServletRequest request = rs.getRequest();
    if ((rs.getRequestSuffix() == null) || (rs.getRequestSuffix().length() == 0)) {
      ServletUtil.forwardToCatalogServices(request, response);
      return;
    }

    sendErrorResponse(response, 0, "Unrecognized request");
  }

  public void doGetINFO(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();
    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (null == ds) return;

      PrintStream pw = new PrintStream(response.getOutputStream());
      response.setHeader("XDODS-Server", getServerVersion());
      response.setContentType("text/html");
      response.setHeader("Content-Description", "dods-description");

      GetInfoHandler di = new GetInfoHandler();
      di.sendINFO(pw, ds, rs);

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  public void doGetHTML(ReqState rs) throws Exception {
    HttpServletResponse response = rs.getResponse();
    HttpServletRequest request = rs.getRequest();
    GuardedDataset ds = null;
    try {
      ds = getDataset(rs);
      if (ds == null) return;

      response.setHeader("XDODS-Server", getServerVersion());
      response.setContentType("text/html");
      response.setHeader("Content-Description", "dods-form");

      // Utilize the getDDS() method to get	a parsed and populated DDS
      // for this server.
      ServerDDS myDDS = ds.getDDS();
      DAS das = ds.getDAS();
      GetHTMLInterfaceHandler2 di = new GetHTMLInterfaceHandler2();
      di.sendDataRequestForm(request, response, rs.getDataSet(), myDDS, das);

    } finally { // release lock if needed
      if (ds != null) ds.release();
    }
  }

  ///////////////////////////////////////////////////////////////////////////////////////////////
  // debugging
  private void makeDebugActions() {
    DebugHandler debugHandler = DebugHandler.get("ncdodsServer");
    DebugHandler.Action act;

    act =
        new DebugHandler.Action("help", "Show help page") {
          public void doAction(DebugHandler.Event e) {
            try {
              doGetHELP(getRequestState(e.req, e.res));
            } catch (Exception ioe) {
              log.error("ShowHelp", ioe);
            }
          }
        };
    debugHandler.addAction(act);

    act =
        new DebugHandler.Action("version", "Show server version") {
          public void doAction(DebugHandler.Event e) {
            e.pw.println("  version= " + getServerVersion());
          }
        };
    debugHandler.addAction(act);
  }

  public String getServerName() {
    return this.getClass().getName();
  }

  /*protected ReqState getRequestState(HttpServletRequest request, HttpServletResponse response) {

    ReqState rs = null;
    // The url and query strings will come to us in encoded form
    // (see HTTPmethod.newMethod())
    String baseurl = request.getRequestURL().toString();
    baseurl = EscapeStrings.escapeURL(baseurl);
    log.debug("doGet baseurl={}", baseurl);

    String query = request.getQueryString();
    query = EscapeStrings.unescapeURLQuery(query);
    log.debug("doGet query={}", query);

    try {
      rs = new ReqState(request, response, getServletConfig(), getServerName(), baseurl, query);
    } catch (BadURLException bue) {
      rs = null;
    }

    return rs;
  }*/

  /**
   * ************************************************************************ Prints the OPeNDAP
   * Server help page to the passed PrintWriter
   *
   * @param pw PrintWriter stream to which to dump the help page.
   */
  private void printHelpPage(PrintWriter pw) {

    pw.println("<h3>OPeNDAP Server Help</h3>");
    pw.println("To access most of the features of this OPeNDAP server, append");
    pw.println(
        "one of the following a eight suffixes to a URL: .das, .dds, .dods, .ddx, .blob, .info,");
    pw.println(".ver or .help. Using these suffixes, you can ask this server for:");
    pw.println("<dl>");
    pw.println("<dt> das  </dt> <dd> Dataset Attribute Structure (DAS)</dd>");
    pw.println("<dt> dds  </dt> <dd> Dataset Descriptor Structure (DDS)</dd>");
    pw.println("<dt> dods </dt> <dd> DataDDS object (A constrained DDS populated with data)</dd>");
    pw.println("<dt> ddx  </dt> <dd> XML version of the DDS/DAS</dd>");
    pw.println(
        "<dt> blob </dt> <dd> Serialized binary data content for requested data set, "
            + "with the constraint expression applied.</dd>");
    pw.println("<dt> info </dt> <dd> info object (attributes, types and other information)</dd>");
    pw.println("<dt> html </dt> <dd> html form for this dataset</dd>");
    pw.println("<dt> ver  </dt> <dd> return the version number of the server</dd>");
    pw.println("<dt> help </dt> <dd> help information (this text)</dd>");
    pw.println("</dl>");
    pw.println("For example, to request the DAS object from the FNOC1 dataset at URI/GSO (a");
    pw.println("test dataset) you would appand `.das' to the URL:");
    pw.println("http://opendap.gso.url.edu/cgi-bin/nph-nc/data/fnoc1.nc.das.");

    pw.println("<p><b>Note</b>: Many OPeNDAP clients supply these extensions for you so you don't");
    pw.println("need to append them (for example when using interfaces supplied by us or");
    pw.println("software re-linked with a OPeNDAP client-library). Generally, you only need to");
    pw.println("add these if you are typing a URL directly into a WWW browser.");
    pw.println("<p><b>Note</b>: If you would like version information for this server but");
    pw.println("don't know a specific data file or data set name, use `/version' for the");
    pw.println("filename. For example: http://opendap.gso.url.edu/cgi-bin/nph-nc/version will");
    pw.println("return the version number for the netCDF server used in the first example. ");

    pw.println("<p><b>Suggestion</b>: If you're typing this URL into a WWW browser and");
    pw.println("would like information about the dataset, use the `.info' extension.");

    pw.println("<p>If you'd like to see a data values, use the `.html' extension and submit a");
    pw.println("query using the customized form.");
  }
  // **************************************************************************

  /**
   * ************************************************************************ Prints the Bad URL
   * Page page to the passed PrintWriter
   *
   * @param pw PrintWriter stream to which to dump the bad URL page.
   */
  private void printBadURLPage(PrintWriter pw) {

    String serverContactName = ThreddsConfig.get("serverInformation.contact.name", "UNKNOWN");
    String serverContactEmail = ThreddsConfig.get("serverInformation.contact.email", "UNKNOWN");
    pw.println("<h3>Error in URL</h3>");
    pw.println("The URL extension did not match any that are known by this");
    pw.println("server. Below is a list of the five extensions that are be recognized by");
    pw.println("all OPeNDAP servers. If you think that the server is broken (that the URL you");
    pw.println("submitted should have worked), then please contact the");
    pw.println("administrator of this server [" + serverContactName + "] at: ");
    pw.println("<a href='mailto:" + serverContactEmail + "'>" + serverContactEmail + "</a><p>");
  }

  ///////////////////////////////////////////////////////
  // utils
  /**
   * @param request
   * @param response
   * @return the request state
   */
  protected ReqState getRequestState(HttpServletRequest request, HttpServletResponse response) {
    ReqState rs = null;

    // Assume url was encoded
    String baseurl = request.getRequestURL().toString();
    baseurl = EscapeStrings.unescapeURL(baseurl);

    // Assume query  was encoded
    String query = request.getQueryString();
    query = EscapeStrings.unescapeURLQuery(query);

    log.info(String.format("OpendapServlet: nominal url: %s?%s", baseurl, query));

    try {
      rs = new ReqState(request, response, this, getServerName(), baseurl, query);
    } catch (Exception bue) {
      rs = null;
    }

    return rs;
  }

  private void checkSize(ServerDDS dds, boolean isAscii) throws Exception {
    long size = computeSize(dds, isAscii);
    // System.err.printf("total (constrained) size=%s\n", size);
    log.debug("total (constrained) size={}", size);
    double dsize = size / (1000 * 1000);
    double maxSize = isAscii ? ascLimit : binLimit; // Mbytes
    if (dsize > maxSize) {
      log.info("Reject request size = {} Mbytes", dsize);
      throw new UnsupportedOperationException(
          "Request too big=" + dsize + " Mbytes, max=" + maxSize);
    }
  }

  // Recursively compute size of the dds to be returned
  private long computeSize(DConstructor ctor, boolean isAscii) throws Exception {
    long projectsize = 0; // accumulate size of projected variables
    long othersize = 0; // accumulate size of non-projected variables
    long fieldsize = 0;
    int projectedcount = 0;
    int fieldcount = 0;
    Enumeration vars = ctor.getVariables();
    while (vars.hasMoreElements()) {
      fieldcount++;
      BaseType field = (BaseType) vars.nextElement();
      fieldsize = computeFieldSize(field, isAscii);
      // accumulate the field sizes
      if (field.isProject()) {
        projectsize += fieldsize;
        projectedcount++;
      } else {
        othersize += fieldsize;
      }
    }
    // Cases to consider:
    // 1. If all of the fields of this ctor are projected,
    //    then return projectsize
    // 2. If none of the fields of this ctor are projected,
    //    then return othersize
    // 3. otherwise, at least one field, but not all, is projected,
    //    => return projectsize;
    if (projectedcount == fieldcount) return projectsize;
    else if (projectedcount == 0) return othersize;
    else {
      assert (projectedcount > 0 && projectedcount < fieldcount);
      return projectsize;
    }
  }

  long computeFieldSize(BaseType bt, boolean isAscii) throws Exception {
    long fieldsize = 0;
    // Figure out what this field is (e.g. primitive or not)
    // Somewhat convoluted.
    if (bt instanceof DConstructor) {
      // simple struct, seq, or grid => recurse
      fieldsize = computeSize((DConstructor) bt, isAscii);
    } else if (bt instanceof DArray) {
      SDArray da = (SDArray) bt;
      // Separate structure arrays from primitive arrays
      if (da.getContainerVar() instanceof DPrimitive) {
        fieldsize = computeArraySize(da);
      } else if (da.getContainerVar() instanceof DStructure) {
        fieldsize = computeSize((DStructure) da.getContainerVar(), isAscii); // recurse
      } else { // Some kind of problem
        throw new NoSuchTypeException("Computesize: unexpected type for " + bt.getLongName());
      }
    } else if (bt instanceof DPrimitive) {
      DPrimitive dp = (DPrimitive) bt;
      if (dp instanceof DString) {
        String v = ((DString) dp).getValue();
        fieldsize = (v == null ? 0 : v.length());
      } else {
        DataType dtype = DODSNetcdfFile.convertToNCType(bt);
        fieldsize = dtype.getSize();
      }
    } else { // Some kind of problem
      throw new NoSuchTypeException("Computesize: unknown type for " + bt.getLongName());
    }
    return fieldsize;
  }

  long computeArraySize(SDArray da) throws Exception {
    assert (da.getContainerVar() instanceof DPrimitive);
    BaseType base = da.getPrimitiveVector().getTemplate();
    DataType dtype = DODSNetcdfFile.convertToNCType(base);
    int elemSize = dtype.getSize();
    int n = da.numDimensions();
    List<Range> ranges = new ArrayList<Range>(n);
    long size = 0;
    for (int i = 0; i < n; i++) {
      ranges.add(new Range(da.getStart(i), da.getStop(i), da.getStride(i)));
      Section s = new Section(ranges);
      size += s.computeSize() * elemSize;
    }
    return size;
  }

  /*
   * *********************** dataset caching ***********************************************
   */

  // any time the server needs access to the dataset, it gets a "GuardedDataset" which allows us to
  // add caching
  // optionally, a session may be established, which allows us to reserve the dataset for that
  // session.
  protected GuardedDataset getDataset(ReqState preq) throws Exception {
    HttpServletRequest req = preq.getRequest();
    String reqPath = preq.getDataSet();

    // see if the client wants sessions
    boolean acceptSession = false;
    String s = req.getHeader("X-Accept-Session");
    if (s != null && s.equalsIgnoreCase("true") && allowSessions) acceptSession = true;

    HttpSession session = null;
    if (acceptSession) {
      // see if theres already a session established, create one if not
      session = req.getSession();
      if (!session.isNew()) {
        GuardedDataset gdataset = (GuardedDataset) session.getAttribute(reqPath);
        if (null != gdataset) {
          if (debugSession)
            System.out.printf(" found gdataset %s in session %s %n", reqPath, session.getId());
          if (log.isDebugEnabled())
            log.debug(" found gdataset " + gdataset + " in session " + session.getId());
          return gdataset;
        }
      }
    }

    NetcdfFile ncd = DatasetHandler.getNetcdfFile(req, preq.getResponse(), reqPath);
    if (null == ncd) return null;

    GuardedDataset gdataset = new GuardedDatasetCacheAndClone(reqPath, ncd, acceptSession);
    // GuardedDataset gdataset = new GuardedDatasetImpl(reqPath, ncd, acceptSession);

    if (acceptSession) {
      String cookiePath = req.getRequestURI();
      String suffix = "." + preq.getRequestSuffix();
      if (cookiePath.endsWith(suffix)) // snip off the suffix
      cookiePath = cookiePath.substring(0, cookiePath.length() - suffix.length());
      session.setAttribute(reqPath, gdataset);
      session.setAttribute(CookieFilter.SESSION_PATH, cookiePath);
      // session.setAttribute("dataset", ncd.getLocation());  // for UsageValve
      // session.setMaxInactiveInterval(30); // 30 second timeout !!
      if (debugSession)
        System.out.printf(
            " added gdataset %s in session %s cookiePath %s %n",
            reqPath, session.getId(), cookiePath);
      if (log.isDebugEnabled())
        log.debug(" added gdataset " + gdataset + " in session " + session.getId());
    } /* else {
        session = req.getSession();
        session.setAttribute("dataset", ncd.getLocation()); // for UsageValve
      } */

    return gdataset;
  }

  //////////////////////////////////////////////////////////////////////////////

  public void parseExceptionHandler(ParseException pe, HttpServletResponse response) {
    try {
      BufferedOutputStream eOut = new BufferedOutputStream(response.getOutputStream());
      response.setHeader("Content-Description", "dods-error");
      response.setContentType("text/plain");

      String msg = pe.getMessage().replace('\"', '\'');

      DAP2Exception de2 = new DAP2Exception(opendap.dap.DAP2Exception.CANNOT_READ_FILE, msg);
      de2.print(eOut);
    } catch (Exception e) {
      System.err.println("parseExceptionHandler: " + e);
    }
  }

  public void dap2ExceptionHandler(DAP2Exception de, ReqState rs) {
    rs.getResponse().setHeader("Content-Description", "dods-error");
    rs.getResponse().setContentType("text/plain");
    try {
      de.print(rs.getResponse().getOutputStream());
    } catch (Exception e) {
      System.err.println("dap2ExceptionHandler: " + e);
    }
  }

  private void sendErrorResponse(HttpServletResponse response, int errorCode, String errorMessage) {
    try {
      log.info(UsageLog.closingMessageForRequestContext(errorCode, -1));
      response.setStatus(errorCode);
      response.setHeader("Content-Description", "dods-error");
      response.setContentType("text/plain");

      PrintWriter pw = new PrintWriter(response.getOutputStream());
      pw.println("Error {");
      pw.println("    code = " + errorCode + ";");
      pw.println("    message = \"" + errorMessage + "\";");

      pw.println("};");
      pw.flush();
    } catch (Exception e) {
      System.err.println("sendErrorResponse: " + e);
    }
  }
}