Extension libs in Tomcat .war

Question

Hi all. After researching ANT for a bit, and the ins-and-outs of .war files, I'm feeling a bit more adventerous with deploying web apps via JWS.
I've been studying the very good Sun/Oracle tutorials on deploying apps via Web Start, but I'm stuck on the JNLP API. I don't understand when or why I need to use the classes in the api such as DownloadService.
I came across having to use the jnlp library when the code I would expect to work fails without error.
(The console opens, appends nothing, closes)
I have all my code in a try block, so it's a bit strange that catch (Exception e) catches nothing. - Or at least keeps the console open :/
(For ease of tracking, questions will be numbered!)
+1) Are there any java logs or anything where I can verify what is going on?+
So, after some reseach, it most likely is because I am using extension libs in my war.
+2) Is it?+
I will add the jnlp file I create is made by a servlet (after taking some params etc from my JSPs).
A copy of the generated file I have saved and hosted on the remote server, which JaNeLa verifies as follows (where jdom.jar and jaxen-1.1.3.jar are simple pointer jnlps to the jars in my /web directory along with all my other files):
JaNeLA Report - version 10.03.10
Report for http://hemmels.dyndns.org/WebTriad/web/jnlp.jnlp
XML encoding not known, but declared as UTF-8
Optimize this application for off-line use by adding the <offline-allowed /> flag.
Downloads can be optimized by specifying a resource size for 'web/PokeTriad.jar'.
The resource download at web/PokeTriad.jar can be optimized by removing the (default) value of download='eager'.
Lazy downloads might not work as expected for web/PokeTriad.jar unless the download 'part' is specified.
Downloads can be optimized by specifying a resource size for 'http:/reference.itags.org/reference/link/?url=img/OntoramaLogo-smaller.jpg'.
Icon loading & use can be optimized by specifying the width and height for http:/reference.itags.org/reference/link/?url=img/OntoramaLogo-smaller.jpg
Report for http://hemmels.dyndns.org/WebTriad/web/jaxen.jnlp
XML encoding not known, but declared as UTF-8
Downloads can be optimized by specifying a resource size for 'lib/jaxen-1.1.3.jar'.
The resource download at lib/jaxen-1.1.3.jar can be optimized by removing the (default) value of main='false'.
Lazy downloads might not work as expected for lib/jaxen-1.1.3.jar unless the download 'part' is specified.
Report for http://hemmels.dyndns.org/WebTriad/web/jdom.jnlp
XML encoding not known, but declared as UTF-8
Downloads can be optimized by specifying a resource size for 'lib/jdom.jar'.
The resource download at lib/jdom.jar can be optimized by removing the (default) value of main='false'.
Lazy downloads might not work as expected for lib/jdom.jar unless the download 'part' is specified. I have added code for using a DownloadService to access these jars from the client (can't remember which page this was from):
try{
               DownloadService ds;
              try {
                  ds = (DownloadService)ServiceManager.lookup("javax.jnlp.DownloadService");
                  Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).info(
                            "DownloadService started!");
              } catch (UnavailableServiceException e) {
                  ds = null;
              if (ds != null) {
                  try {
                      // determine if a particular resource is cached
                      URL url = new URL("http://hemmels.dyndns.org/WebTriad/web/jdom.jar");
                      boolean cached = ds.isResourceCached(url, "1.0");
                      // remove the resource from the cache
                      if (cached) {
                          ds.removeResource(url, "1.0");
                      // reload the resource into the cache
                      DownloadServiceListener dsl = ds.getDefaultProgressWindow();
                      ds.loadResource(url, "1.0", dsl);
                  } catch (Exception e) {
                      e.printStackTrace();
              }3) Is this right? I need to use the jnlp api to access extension libs from Tomcat?
This confirms my suspicions with the problem stemming from libraries in my war file because now when running the app I get the following error:
29-Oct-2010 00:35:25 runtime.PokeClient <init>
INFO: DownloadService started!
29-Oct-2010 00:35:25 runtime.PokeClient <init>
SEVERE: jdom lib could not be cached!
com.sun.deploy.net.FailedDownloadException: Unable to load resource: (http://hemmels.dyndns.org/WebTriad/web/jdom.jar, 1.0)
     at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
     at com.sun.javaws.LaunchDownload$DownloadTask.call(Unknown Source)
     at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
     at java.util.concurrent.FutureTask.run(Unknown Source)
     at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
Caused by:
java.io.IOException: missing version response from server
     at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source)
     at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source)
     at com.sun.javaws.LaunchDownload$DownloadTask.call(Unknown Source)
     at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
     at java.util.concurrent.FutureTask.run(Unknown Source)
     at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)which is thrown when the code hits:
DownloadService ds;
              try {
                  ds = (DownloadService)ServiceManager.lookup("javax.jnlp.DownloadService");
                  Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).info(
                            "DownloadService started!");
              } catch (UnavailableServiceException e) {
                  ds = null;
              if (ds != null) {
                  try {
                      // determine if a particular resource is cached
                      URL url = new URL("http://hemmels.dyndns.org/WebTriad/web/jdom.jar");
                      boolean cached = ds.isResourceCached(url, "1.0");
                      // remove the resource from the cache
                      if (cached) {
                          ds.removeResource(url, "1.0");
                      // reload the resource into the cache
                      DownloadServiceListener dsl = ds.getDefaultProgressWindow();
                      ds.loadResource(url, "1.0", dsl);
                      Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).info(
                                 "jdom lib is now cached!");
                  } catch (Exception e) {
                      Logger.getLogger(Logger.GLOBAL_LOGGER_NAME).severe(
                                  "jdom lib could not be cached!");
                      e.printStackTrace();
              }So before I go any further into guessing (have been googling/lurking in this forum for this problem for a week and found nothing), +4) am I along the right lines (i.e. am I trying to do something incorrectly or worse, something you can't do), or do I need to implement the "javax.jnlp.DownloadService" properly?+
Other information would be that the jar file ("http://hemmels.dyndns.org/WebTriad/web/jdom.jar") is accessable from a browser.
Appreciate any replies and the time spent reading.
Edited by: 798437 on Oct 28, 2010 11:44 PM
Spelling.
Edited by: 798437 on Oct 28, 2010 11:45 PM
code blocks
EDIT: I understand the issue java.io.IOException: missing version response from server, is from versioned extensions or something, having googled this I found I need the following version.xml in the /web folder:
<jnlp-versions>
   <resource>
      <pattern>
         <name>jaxen-1.1.3.jar</name>
         <version-id>1.0</version-id>
         <locale>en_GB</locale>
         <locale>en</locale>
      </pattern>
      <file>jaxen-1.1.3.jar</file>
  </resource>
  <resource>
      <pattern>
         <name>jdom.jar</name>
         <version-id>1.0</version-id>
         <locale>en_GB</locale>
         <locale>en</locale>
      </pattern>
      <file>jdom.jar</file>
  </resource>
</jnlp-versions>+5) Do I need a JNLPDownloadServlet or something or this this something different, and again, am I down the wrong path?+
Edited by: 798437 on Oct 28, 2010 11:47 PM

Answer 1

All the above seems to be irrelvant.
My console was closing because the client's stream was empty, and I was trying to read from it.
This was causing an Exception in my client code I wasn't catching (shame on me).
Consider it a hard lesson learnt :)