Using Network Installed JRE for JNLP

Question

Hello All;
First post here so I hope I pull this off correctly. I have been using these forums a bit to help me develop the JNLP deployment of an inhouse application. Basically I have a JAR file, and am using a servlet via tomcat to dynamically generate my JNLP file (since I have params passed to the jar) and push to the user's browser. I then have the jnlp mime type set via tomcat so that when the servlet flushes the stream, javaws starts up and processes the application. The problem I have is that I am telling the jnlp file to use java version 1.5+, however, there are some users here that have Java 1.4 installed locally. We have Java 1.5 installed on our server, and most of our applications use a "driver" that sets up the java home to that directory. Is there a way that I can tell JNLP to use that installation of the JRE? The reason I dont want to use the 'autoupdate' function is because not all users have the proper permissions to install applications on their system. Here is the code I use in my servlet:
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.csc.eri.config.ERIConfigFile;
import com.csc.eri.logger.ERILoggerFactory;
import com.csc.eri.logger.IERILogger;
* Servlet designed to handle all JNLP application requests
public class JnlpServlet  extends HttpServlet {
     private static final long serialVersionUID      = 1L;
     private static IERILogger logger                = ERILoggerFactory.create();
     String jnlpSpec;
     String jnlpCB;
     String title;
     String vendor;
     String homepage;
     String desc;
     String descShort;
     String descTool;
     String javaVersion;
     String javaLocation;
     String jarLocation;
     String mainClass;
     String cacheDays;
     String fileName;
     String[] jvmOpts;
     String[] extensionNames;
     String[] extensionLocations;
     String[] applicationOrder;
     boolean allowNewer;
     boolean showJnlp;
      * Initialize all variables
      * @throws IOException
     private void initVars() throws IOException {
          ERIConfigFile config = ERIConfigFile.getInstance();
          jnlpSpec                = config.getProperty("jnlp.spec");
          jnlpCB                    = config.getProperty("jnlp.codebase");
          title                    = config.getProperty("jnlp.title");
          vendor                    = config.getProperty("jnlp.vendor");
          homepage                = config.getProperty("jnlp.homepage");
          desc                    = config.getProperty("jnlp.description");
          allowNewer               = config.getProperty("jnlp.allow_newer_jvm")
                                                  .toLowerCase()
                                                  .equals("yes")?
                                                            true : false;
          showJnlp               = config.getProperty("jnlp.show_jnlp")
                                                  .toLowerCase()
                                                  .equals("yes")?
                                                            true : false;
          // Test variables so we dont launch on error
          try {          
               testVars();               
          } catch (NullPointerException npe) {
               throw new IOException(npe.getMessage());
      * Method to ensure that all data was properly loaded from the
      * configuration file.  We want to make sure that everything
      * is fine and display any messages to the screen before
      * the application is launched.
     private void testVars() {
          logger.info("Checking Configuration");
          ArrayList<String> errList      = new ArrayList<String>();
          ArrayList<String> warnList      = new ArrayList<String>();
          // Errors
          if (jnlpSpec      == null) errList.add("Missing Spec");
          if (jnlpCB           == null) errList.add("Missing Codebase");
          if (title          == null) errList.add("Missing Title");
          if (vendor          == null) errList.add("Missing Vendor");
          if (homepage     == null) errList.add("Missing Homepage");
          if (desc        == null) errList.add("Missing Description");
          if (javaVersion == null) errList.add("Missing Java Version");
          if (jarLocation == null) errList.add("Missing Jar Location");
          if (mainClass   == null) errList.add("Missing Main Class");
          if (cacheDays   == null) errList.add("Missing Cache Days");
          if (applicationOrder == null) errList.add("Missing Application Param Order");
          if (fileName    == null) errList.add("Missing File Name");
          // Warnings
          if (javaLocation == null) warnList.add("Missing Java Location");
      * Implementation of the doGet method.  Creates the jnlp xml stream
      * and outputs to the browser
     public void doGet(HttpServletRequest request, HttpServletResponse response)
          throws ServletException, IOException
          logger.info("Servlet Initialized");
          // Init variables
          initVars();
          // Generate output
          String outputString = generateOutputString(request);
          // This is the file name as cached by the browser
          String attachment = "inline; filename=\"" + fileName + "\"";     
          // Set our MIME type
          response.setContentType("application/x-java-jnlp-file");  
          // Add a header that states the max age or the cache
          response.addHeader("Cache-Control", "max-age=" + cacheDays);  
          // Attach the inline content
          response.addHeader("Content-disposition", attachment); 
          // Prepare our stream writer
          OutputStreamWriter out = new OutputStreamWriter(response.getOutputStream()); 
          // Push to the browser
          logger.info("Posting To Browser");
          out.write(outputString.toString()); 
          out.flush(); 
          out.close();
      * Posts information to the browser
     public void doPost(HttpServletRequest request,
              HttpServletResponse response)
          throws ServletException, IOException
          doGet(request, response);
      * Generate the servlet's output stream.  This method uses
      * all of the information gathered from the eri configuration
      * file
      * @param request     The request sent to the servlet, needed
      *                          to parse the arguments
      * @return               Return the string output
     private String generateOutputString(HttpServletRequest request) {
          // Create our output string
          StringBuffer outputString = new StringBuffer();
          outputString.append(JnlpFieldCreator.xmlHeaderBlock(          "1.0", "utf-8"));
          outputString.append(JnlpFieldCreator.jnlpSpecBlock(               jnlpSpec, jnlpCB));
          outputString.append(JnlpFieldCreator.informationBlock(          title,
                                                                                     vendor,
                                                                                     homepage,
                                                                                     desc,
                                                                                     descShort,
                                                                                     descTool));
          outputString.append(JnlpFieldCreator.securityBlock());
          outputString.append(JnlpFieldCreator.resourcesBlock(          javaVersion,
                                                                                     allowNewer,
                                                                                     javaLocation,
                                                                                     jarLocation,
                                                                                     jvmOpts,
                                                                                     extensionNames,
                                                                                     extensionLocations));
          outputString.append(JnlpFieldCreator.applicationDescBlock(     mainClass,
                                                                                         request,
                                                                                         applicationOrder));
          outputString.append(JnlpFieldCreator.jnlpEndBlock());
          return outputString.toString();
}

Answer 1

Also here is the jnlp file created, sorry i ran out of chars in my first post
<?xml version="1.0" encoding="utf-8"?>
<jnlp spec="1.0+" codebase="http://ad292673:8080/eri/app">
<information>
     <title>Electronic Release Version 4</title>
     <vendor>---</vendor>
     <homepage href="http://ad292673:8080/" />
     <description>Application for auditing and releasing drawings</description>
     <description kind="short">Electronic Release is used to help users
          audit and perform release actions on part drawings, tooling drawings, table
          of limits, and web drawings</description>
     <description kind="tooltip">ERI v4.0</description>
</information>
<security>
     <all-permissions/>
</security>
<resources>
     <j2se version="1.5*" href="http://java.sun.com/products/autodl/j2se"/>
     <jar href="./eri-view_ddmdemo.jar" main="true" part="mainClass" download="eager"/>
     <extension name="EclipseLibs" href="./jnlp/EclipseLibs.jnlp"/>
     <extension name="EriLibs" href="./jnlp/EriLibs.jnlp"/>
     <extension name="JdomLibs" href="./jnlp/JdomLibs.jnlp"/>
     <property name="eri.stage" value="devl" />
</resources>
<application-desc main-class="com.csc.eri.view.swt.Application">
     <argument>c087919</argument>
     <argument>ddm</argument>
     <argument>release</argument>
     <argument>-</argument>
     <argument>-</argument>
     <argument>09005b8b829bf8b6</argument>
</application-desc>
</jnlp>