DTS: DAP2 Test Server

Overview

This document should help you get started configuring the DAP2 Test Server (DTS).

Here you will find:

• Installation instructions.
• Configuration documentation.
• Start and stop instructions.
• Release Notes

The DTS is implemented as a Java Servlet and utilizes the Java Servlet API to allow it to act as a "plug-in" to Java Servlet "containers" such as the Tomcat server.

The DTS is primarily used to test the java implementation of the DAP2 protocol. It can also be used to test DAP2 client libraries by having them read from the DTS. This servlet will take any DDS it finds in it's DDScache (see below) and populate it with invented data per client request. This allows the testing of unusual DDS structures.

The DTS was developed, compiled, and tested using the javac 1.4.1 compiler, the 1.4.1 Java Virtual Machine, and Jakarta Tomcat 5.5.20 (which also provided the Java Servlet API (javax.servlet) packages).

Installing the DTS

• Get Tomcat
• Install Tomcat
• Set the environment variable CATALINA_HOME to the location of your Tomcat instance.
• Note: From here on this document assumes that you are running the DTS inside an instance of Tomcat and that you have set the environment variable CATALINA_HOME to point to the top level of your Tomcat installation.
• Take the dts.war file from the distribution bundle and place it in $CATALINA_HOME/webapps directory.
• Start Tomcat.
• Rejoice.

• Alter configuration.
• Stop Tomcat.
• Start Tomcat.
• Resume rejoice mode.

Servlet Configuration

The DTS gets its configuration from the servlet's web.xml file. The default location of the web.xml file is (at least in Tomcat 4.1) in $CATALINA_HOME/webapps/opendap/WEB-INF/web.xml If the servlet context changes then things get renamed accordingly. The servlet context is represented by the basename of the directory $CATALINA_HOME/webapps/opendap, thus by default the servlet context is "opendap"

<init-param> Elements

Inside the web.xml file, the DTS uses a number of <init-param> elements inside of it's <servlet> element to get specific configuration information.

<init-param>'s common to all OPeNDAP servlets are:

• DebugOn - This controls output 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. Common values are : showRequest, showResponse, showException, and probeRequest Other debugging values that are specific to each servlet should be documented in each servlets javadoc documentation.
  Example:

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

  Default: If this parameter is not set, or the value field is empty then debugging instrumentation is not turned on.
  


• DDXcache - This is should be set to the directory containing the DDX files for the data sets used by the servlet. Some servlets have been developed that do not use DDX's that are cached on the disk, however the default behavior is for the servlet to load DDX images from disk.
  Example:

  <init-param>
              <param-name>DDXcache</param-name>
              <param-value>/usr/OPeNDAP/sdds-testsuite/ddx/</param-value>
              </init-param>
          

  Default: If this parameter is not set (does not appear in as an <init-param>) then it is set to $TOMCATHOME/webapps/opendap/datasets/servlet-name/ddx (where servlet-nameis the same as the name specified in the <servlet-name> element of the servlet configuration) .
  


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

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

  Default: If this parameter is not set (does not appear in as an <init-param>) then it is set to $TOMCATHOME/webapps/opendap/datasets/servlet-name/dds (where servlet-name is the same as the name specified in the <servlet-name> element of the servlet configuration)
  


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

          <init-param>
          <param-name>DAScache</param-name>
          <param-value>/usr/OPeNDAP/sdds-testsuite/das/</param-value>
          </init-param>
      

  Default: If this parameter is not set (does not appear in as an <init-param>) then it is set to $TOMCATHOME/webapps/opendap/datasets/servlet-name/das (where servlet-name is the same as the name specified in the <servlet-name> element of the servlet configuration) .
  


• 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 data set specific "over-ride" files (see below), any data set specific additional information files (see below), and any servlet specific information files(see below).
  Example:

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

  Default: If this parameter is not set (does not appear in as an <init-param>) then it is set to $TOMCATHOME/webapps/opendap/datasets/servlet-name/info (where servlet-name is the same as the name specified in the <servlet-name> element of the servlet configuration)
  


• SchemaLocation - The value of this <init-param> should be set to the URL that points to the OPeNDAP XML schema file used by the servlet. In general this should not be set and allowed to be it's default.
  Example:

          <init-param>
          <param-name>SchemaLocation</param-name>
          <param-value> http://dods.coas.oregonstate.edu:8080/opendap/opendap.xsd</param-value>
          </init-param>
      

  Default: If this parameter is not set (does not appear in as an <init-param>) then the SchemaLocation is set to http://hostname/opendap/opendap.xsd where hostname is the hostname and socket of the servlet engine. For example, if my hostname is opendap.org and my servlet engine is running on port 8080 the my default SchemaLocation is:
  http://opendap.org:8080/opendap/opendap.xsd
  
  
• SequenceLength - This <init-param> sets the number of rows each Sequence returned by the DTS will have. Common values are typically small (5-100) for simple testing. If you are to testing client code against the DTS you may wish to use a large value (>50000) here to check the client's ability to handle large Sequences.
  Example:

              <init-param>
              <param-name>SequenceLength</param-name>
              <param-value>100</param-value>
              </init-param>
          

  Default: Is set to 5 if this parameter is not set (As in does not appear as an <init-param> in the servlet section of the web.xml file).
  

Example of web.xml content:

In this example SequenceLength gets set to 100.

    <!DOCTYPE web-app
            PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
            "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">
    <web-app>
    
        <servlet>

            <servlet-name>dts</servlet-name>
            <servlet-class>opendap.servers.test.dts</servlet-class>
    
            <init-param>
                <param-name>DebugOn</param-name>
                <param-value>showRequest CE CEEvaluator</param-value>
            </init-param>
            <init-param>
                <param-name>SequenceLength</param-name>
                <param-value>100</param-value>
            </init-param>
    
            <load-on-startup>1</load-on-startup>
        </servlet>
    
    
        <servlet-mapping>
            <servlet-name>dts</servlet-name>
            <url-pattern>/dts</url-pattern>
        </servlet-mapping>
        <servlet-mapping>
            <servlet-name>dts</servlet-name>
            <url-pattern>/dts/*</url-pattern>
        </servlet-mapping>
        <servlet-mapping>
            <servlet-name>dts</servlet-name>
            <url-pattern>*</url-pattern>
        </servlet-mapping>
    
    </web-app>
    

Starting and Stoping the DTS

Start the DTS with this command:

$CATALINA_HOME/bin/startup.sh &

Stop the DTS with this Command:

$CATALINA_HOME/bin/shutdown.sh &

We hope we hope you find this software useful, and we welcome your questions and comments.

To Contact Us:

Technical Support: support@opendap.org