Package opendap.dts

Class DTSServlet

  • All Implemented Interfaces:
    Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig
    public class DTSServlet
extends opendap.servlet.AbstractServlet
    Purpose:
    This is the OPeNDAP Test servlet (dts). It allows the owner of the server to deliver data in ANY valid DDS to a client. This DDS will be filled with invented data if the client requests a DataDDS. This kind of test fixture is useful for evaluating a clients ability to handle the various complexities of the OPeNDAP data types.

    Configuration:
    The AbstractServlet relies on the javax.servlet.ServletConfig interface (in particular the getInitParameter() method) to retrieve configuration information used by the servlet. InitParameters:

    • DebugOn - This controls ouput to the terminal from which the servlet engine was launched. The value is a list of flags that turn on debugging instrumentation in different parts of the code. Values are:
      • showRequest - Show information about the clients request.
      • showResponse - Show information about the servlets response.
      • probeRequest - Show an exhaustive amount of information about the clients request object.

    • INFOcache - This is should be set to the directory containing the files used by the ".info" service for the servlet. This directory should contain any dataset specific "over-ride" files (see below), any dataset specific additional information files (see below), and any servlet specific information files(see below).

    • DDScache - This is should be set to the directory containing the DDS files for the datasets used by the servlet. Some servlets have been developed that do not use DDS's that are cached on the disk, however the default behaviour is for the servlet to load DDS images from disk.

    • DAScache - This is should be set to the directory containing the DAS files for the datasets used by the servlet. Some servlets have been developed that do not use DAS's that are cached on the disk, however the default behaviour is for the servlet to load DAS images from disk.

    Here is an example entry from the web.xml file (for tomcat3.3a) for the OPeNDAP Test Server (DTS): 

             <servlet>
            <servlet-name>
                dts
            </servlet-name>

            <servlet-class>
                opendap.servers.dts
            </servlet-class>

            <init-param>
                <param-name>DebugOn</param-name>
                <param-value>showRequest showResponse </param-value>
            </init-param>

            <init-param>
                <param-name>INFOcache</param-name>
                <param-value>/usr/Java-OPeNDAP/sdds-testsuite/info/</param-value>
            </init-param>

            <init-param>
                <param-name>DDScache</param-name>
                <param-value>/usr/Java-OPeNDAP/sdds-testsuite/dds/</param-value>
            </init-param>

            <init-param>
                <param-name>DAScache</param-name>
                <param-value>/usr/Java-OPeNDAP/sdds-testsuite/das/</param-value>
            </init-param>
        </servlet>
    See Also:
    Serialized Form

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static org.slf4j.Logger log  

      • Fields inherited from class opendap.servlet.AbstractServlet

        allowDeflate

    • Constructor Summary

      Constructors 
      Constructor Description
      DTSServlet()
      ************************************************************************ Intitializes the servlet.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void anyExceptionHandler​(Throwable e, opendap.servlet.ReqState rs)
      Sends an error to the client.
      void badURL​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
      Sends an html document to the client explaining that they have used a poorly formed URL and then the help page...
      void dap2ExceptionHandler​(opendap.dap.DAP2Exception de, javax.servlet.http.HttpServletResponse response)
      Sends a OPeNDAP DAP2 error to the client.
      void doDebug​(opendap.servlet.ReqState rs)
      Handler for debug requests;
      protected boolean doDebugCmd​(String cmd, StringTokenizer tz, PrintStream pw)  
      void doGet​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
      Handles incoming requests from clients.
      void doGetASC​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP ascii data requests.
      void doGetBLOB​(opendap.servlet.ReqState rs)
      Handler for the client's data request.
      void doGetCatalog​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP catalog.xml requests.
      void doGetDAP2Data​(opendap.servlet.ReqState rs)
      Handler for the client's data request.
      void doGetDAS​(opendap.servlet.ReqState rs)
      Handler for the client's DAS request.
      void doGetDDS​(opendap.servlet.ReqState rs)
      Handler for the client's DDS request.
      void doGetDDX​(opendap.servlet.ReqState rs)
      Handler for the client's DDX request.
      void doGetDIR​(opendap.servlet.ReqState rs)
      Handler for the client's directory request.
      void doGetHELP​(opendap.servlet.ReqState rs)
      Handler for the client's help request.
      void doGetHTML​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP .html requests.
      void doGetINFO​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP info requests.
      void doGetStatus​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP status requests; not publically available, used only for debugging
      void doGetSystemProps​(opendap.servlet.ReqState rs)
      Handler for OPeNDAP status requests; not publically available, used only for debugging
      void doGetVER​(opendap.servlet.ReqState rs)
      Handler for the client's version request.
      protected opendap.servlet.GuardedDataset getDataset​(opendap.servlet.ReqState rs)
      ************************************************************************ This method must be implemented locally for each OPeNDAP server.
      protected opendap.servlet.ReqState getRequestState​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)  
      String getRootPath()
      Getter function for rootpath
      String getServerName()
      In this (default) implementation of the getServerName() method we just get the name of the servlet and pass it back.
      String getServerVersion()
      This method returns a String containing the OPeNDAP Server Version...
      void init()  
      void IOExceptionHandler​(IOException e, opendap.servlet.ReqState rs)
      Sends an error to the client.
      void parseExceptionHandler​(opendap.dap.parsers.ParseException pe, javax.servlet.http.HttpServletResponse response)
      Turns a ParseException into a OPeNDAP DAP2 error and sends it to the client.
      protected void printCatalog​(opendap.servlet.ReqState rs, PrintWriter os)  
      protected void printStatus​(PrintWriter os)  
      void probeRequest​(PrintStream ps, opendap.servlet.ReqState rs)
      This is a bit of instrumentation that I kept around to let me look at the state of the incoming HttpServletRequest from the client.
      void sendDODSError​(opendap.servlet.ReqState rs, String clientMsg, String serverMsg)
      Sends a OPeNDAP DAP2 error (type UNKNOWN ERROR) to the client and displays a message on the server console.

      • Methods inherited from class opendap.servlet.AbstractServlet

        badURL, doDebugCmd, printDODSException, printThrowable, probeRequest, sendDODSError, setLog, setRootpath

      • Methods inherited from class javax.servlet.http.HttpServlet

        doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service

      • Methods inherited from class javax.servlet.GenericServlet

        destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

    • Field Detail

      • log

        public static org.slf4j.Logger log

    • Constructor Detail

      • DTSServlet

        public DTSServlet()
        ************************************************************************ Intitializes the servlet. Init (at this time) basically sets up the object opendap.util.util.Debug from the debuggery flags in the servlet InitParameters. The Debug object can be referenced (with impunity) from anywhere in the VM.

    • Method Detail

      • getRootPath

        public String getRootPath()
        Getter function for rootpath
        Returns:
        rootpath

      • getServerVersion

        public String getServerVersion()
        This method returns a String containing the OPeNDAP Server Version...
        Specified by:
        getServerVersion in class opendap.servlet.AbstractServlet

      • getDataset

        protected opendap.servlet.GuardedDataset getDataset​(opendap.servlet.ReqState rs)
                                             throws opendap.dap.DAP2Exception,
                                                    IOException,
                                                    opendap.dap.parsers.ParseException
        ************************************************************************ This method must be implemented locally for each OPeNDAP server. The local implementation of this method is the key piece for connecting any localized data types that are derived from the opendap.Server types back into the running servlet.

        This method should do the following:

        • Make a new ServerFactory (aka BaseTypeFactory) for the dataset requested.
        • Instantiate a ServerDDS using the ServerFactory and populate it (this could be accomplished by just opening a (cached?) DDS in a file and parsing it)
        • Return this freshly minted ServerDDS object (to the servlet code where it is used.)
        Specified by:
        getDataset in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState object for this particular client request.
        Returns:
        The ServerDDS object all parsed and ready to roll.
        Throws:
        opendap.dap.DAP2Exception
        IOException
        opendap.dap.parsers.ParseException

      • init

        public void init()
          throws javax.servlet.ServletException
        Overrides:
        init in class javax.servlet.GenericServlet
        Throws:
        javax.servlet.ServletException

      • parseExceptionHandler

        public void parseExceptionHandler​(opendap.dap.parsers.ParseException pe,
                                  javax.servlet.http.HttpServletResponse response)
        Turns a ParseException into a OPeNDAP DAP2 error and sends it to the client.
        Overrides:
        parseExceptionHandler in class opendap.servlet.AbstractServlet
        Parameters:
        pe - The ParseException that caused the problem.
        response - The HttpServletResponse for the client.

      • dap2ExceptionHandler

        public void dap2ExceptionHandler​(opendap.dap.DAP2Exception de,
                                 javax.servlet.http.HttpServletResponse response)
        Sends a OPeNDAP DAP2 error to the client.
        Overrides:
        dap2ExceptionHandler in class opendap.servlet.AbstractServlet
        Parameters:
        de - The OPeNDAP DAP2 exception that caused the problem.
        response - The HttpServletResponse for the client.

      • IOExceptionHandler

        public void IOExceptionHandler​(IOException e,
                               opendap.servlet.ReqState rs)
        Sends an error to the client. fix: The problem is that if the message is already committed when the IOException occurs, the headers dont get set.
        Overrides:
        IOExceptionHandler in class opendap.servlet.AbstractServlet
        Parameters:
        e - The exception that caused the problem.
        rs - The ReqState for the client.

      • anyExceptionHandler

        public void anyExceptionHandler​(Throwable e,
                                opendap.servlet.ReqState rs)
        Sends an error to the client.
        Overrides:
        anyExceptionHandler in class opendap.servlet.AbstractServlet
        Parameters:
        e - The exception that caused the problem.
        rs - The ReqState for the client.

      • sendDODSError

        public void sendDODSError​(opendap.servlet.ReqState rs,
                          String clientMsg,
                          String serverMsg)
                   throws Exception
        Sends a OPeNDAP DAP2 error (type UNKNOWN ERROR) to the client and displays a message on the server console.
        Parameters:
        rs - The client's ReqState object.
        clientMsg - Error message String to send to the client.
        serverMsg - Error message String to display on the server console.
        Throws:
        Exception

      • doGetDAS

        public void doGetDAS​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for the client's DAS request. Operates on the assumption that the DAS information is cached on a disk local to the server. If you don't like that, then you better override it in your server :)

        Once the DAS has been parsed it is sent to the requesting client.

        Overrides:
        doGetDAS in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState of this client request. Contains all kinds of important stuff.
        Throws:
        Exception
        See Also:
        ReqState

      • doGetDDS

        public void doGetDDS​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for the client's DDS request. Requires the getDDS() method implemented by each server localization effort.

        Once the DDS has been parsed and constrained it is sent to the requesting client.

        Overrides:
        doGetDDS in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState of this client request. Contains all kinds of important stuff.
        Throws:
        Exception
        See Also:
        ReqState

      • doGetDDX

        public void doGetDDX​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for the client's DDX request. Requires the getDDX() method implemented by each server localization effort.

        Once the DDX has been parsed and constrained it is sent to the requesting client.

        Overrides:
        doGetDDX in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState of this client request. Contains all kinds of important stuff.
        Throws:
        Exception
        See Also:
        ReqState

      • doGetBLOB

        public void doGetBLOB​(opendap.servlet.ReqState rs)
               throws Exception
        Handler for the client's data request. Requires the getDDS() method implemented by each server localization effort.

        Once the DDS has been parsed, the data is read (using the class in the localized server factory etc.), compared to the constraint expression, and then sent to the client.

        Overrides:
        doGetBLOB in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState of this client request. Contains all kinds of important stuff.
        Throws:
        Exception
        See Also:
        ReqState

      • doGetDAP2Data

        public void doGetDAP2Data​(opendap.servlet.ReqState rs)
                   throws Exception
        Handler for the client's data request. Requires the getDDS() method implemented by each server localization effort.

        Once the DDS has been parsed, the data is read (using the class in the localized server factory etc.), compared to the constraint expression, and then sent to the client.

        Overrides:
        doGetDAP2Data in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The ReqState of this client request. Contains all kinds of important stuff.
        Throws:
        IOException
        javax.servlet.ServletException
        Exception
        See Also:
        ReqState

      • doGetDIR

        public void doGetDIR​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for the client's directory request.

        Returns an html document to the client showing (a possibly pseudo) listing of the datasets available on the server in a directory listing format.

        The bulk of this code resides in the class opendap.servlet.GetDirHandler and documentation may be found there.

        Overrides:
        doGetDIR in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetDirHandler

      • doGetVER

        public void doGetVER​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for the client's version request.

        Returns a plain text document with server version and OPeNDAP core version #'s

        Overrides:
        doGetVER in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception

      • doGetHELP

        public void doGetHELP​(opendap.servlet.ReqState rs)
               throws Exception
        Handler for the client's help request.

        Returns an html page of help info for the server

        Overrides:
        doGetHELP in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception

      • badURL

        public void badURL​(javax.servlet.http.HttpServletRequest request,
                   javax.servlet.http.HttpServletResponse response)
            throws Exception
        Sends an html document to the client explaining that they have used a poorly formed URL and then the help page...
        Parameters:
        request - The client's request
        response - The client response
        Throws:
        Exception

      • doGetASC

        public void doGetASC​(opendap.servlet.ReqState rs)
              throws Exception
        Handler for OPeNDAP ascii data requests. Returns the request data as a comma delimited ascii file. Note that this means that the more complex OPeNDAP structures such as Grids get flattened...

        Modified 2/8/07 jcaron to not make a DConnect2 call to itself

        Overrides:
        doGetASC in class opendap.servlet.AbstractServlet
        Parameters:
        rs - the decoded Request State
        Throws:
        Exception

      • doGetINFO

        public void doGetINFO​(opendap.servlet.ReqState rs)
               throws Exception
        Handler for OPeNDAP info requests. Returns an HTML document describing the contents of the servers datasets.

        The bulk of this code resides in the class opendap.servlet.GetInfoHandler and documentation may be found there.

        Overrides:
        doGetINFO in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetInfoHandler

      • doGetHTML

        public void doGetHTML​(opendap.servlet.ReqState rs)
               throws Exception
        Handler for OPeNDAP .html requests. Returns the OPeNDAP Web Interface (aka The Interface From Hell) to the client.

        The bulk of this code resides in the class opendap.servlet.GetHTMLInterfaceHandler and documentation may be found there.

        Overrides:
        doGetHTML in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetHTMLInterfaceHandler

      • doGetCatalog

        public void doGetCatalog​(opendap.servlet.ReqState rs)
                  throws Exception
        Handler for OPeNDAP catalog.xml requests.
        Overrides:
        doGetCatalog in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetHTMLInterfaceHandler

      • printCatalog

        protected void printCatalog​(opendap.servlet.ReqState rs,
                            PrintWriter os)
                     throws IOException
        Overrides:
        printCatalog in class opendap.servlet.AbstractServlet
        Throws:
        IOException

      • doDebug

        public void doDebug​(opendap.servlet.ReqState rs)
        Handler for debug requests;
        Overrides:
        doDebug in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState object.

      • doGetSystemProps

        public void doGetSystemProps​(opendap.servlet.ReqState rs)
                      throws Exception
        Handler for OPeNDAP status requests; not publically available, used only for debugging
        Overrides:
        doGetSystemProps in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetHTMLInterfaceHandler

      • doGetStatus

        public void doGetStatus​(opendap.servlet.ReqState rs)
                 throws Exception
        Handler for OPeNDAP status requests; not publically available, used only for debugging
        Overrides:
        doGetStatus in class opendap.servlet.AbstractServlet
        Parameters:
        rs - The client's ReqState
        Throws:
        Exception
        See Also:
        GetHTMLInterfaceHandler

      • printStatus

        protected void printStatus​(PrintWriter os)
        Overrides:
        printStatus in class opendap.servlet.AbstractServlet

      • probeRequest

        public void probeRequest​(PrintStream ps,
                         opendap.servlet.ReqState rs)
        This is a bit of instrumentation that I kept around to let me look at the state of the incoming HttpServletRequest from the client. This method calls the get* methods of the request and prints the results to standard out.
        Parameters:
        ps - The PrintStream to send output.
        rs - The ReqState object to probe.

      • getServerName

        public String getServerName()

        In this (default) implementation of the getServerName() method we just get the name of the servlet and pass it back. If something different is required, override this method when implementing the getDDS() and getServerVersion() methods.

        This is typically used by the getINFO() method to figure out if there is information specific to this server residing in the info directory that needs to be returned to the client as part of the .info rs.getResponse().

        Overrides:
        getServerName in class opendap.servlet.AbstractServlet
        Returns:
        A string containing the name of the servlet class that is running.

      • doGet

        public void doGet​(javax.servlet.http.HttpServletRequest request,
                  javax.servlet.http.HttpServletResponse response)
        Handles incoming requests from clients. Parses the request and determines what kind of OPeNDAP response the client is requesting. If the request is understood, then the appropriate handler method is called, otherwise an error is returned to the client.

        This method is the entry point for DTSServlet.

        Overrides:
        doGet in class opendap.servlet.AbstractServlet
        Parameters:
        request - The client's HttpServletRequest request object.
        response - The server's HttpServletResponse response object.
        See Also:
        ReqState

      • getRequestState

        protected opendap.servlet.ReqState getRequestState​(javax.servlet.http.HttpServletRequest request,
                                                   javax.servlet.http.HttpServletResponse response)
                                            throws opendap.dap.DAP2Exception
        Overrides:
        getRequestState in class opendap.servlet.AbstractServlet
        Parameters:
        request -
        Returns:
        the request state
        Throws:
        opendap.dap.DAP2Exception