Error "cannot locate object' launching app with Web Start

Question

Hello,
I receive the error shown below when launching a Java application and cannot figure out where to begin with debugging. It was developed under Netbeans 5.0.
You can recreate the error by launching this application:
http://www.mikenaglich.net/ztest17.jnlp
Error text and JNLP file follow. I am really puzzled and would appreciate any help. Thanks.
Mike
Error Text
========
The XML page cannot be displayed
Cannot view XML input using style sheet. Please correct the error and then click the Refresh button, or try again later.
The system cannot locate the object specified. Error processing resource 'http://www.netbeans.org/jnlp/DTD/jnlp.dtd'.
App JNLP File
===========
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jnlp PUBLIC "-//Sun Microsystems, Inc.//DTD JNLP 1.5//EN" "http://www.netbeans.org/jnlp/DTD/jnlp.dtd">
<jnlp codebase="http://www.mikenaglich.net" href="ztest17.jnlp">
<information>
<title>ztest17</title>
<vendor>Mike Naglich</vendor>
<homepage href="www.mikenaglich.net"/>
<description> </description>
<icon href="default"/>
<offline-allowed/>
<shortcut online="true">
<desktop/>
</shortcut>
</information>
<resources>
<j2se href="http://java.sun.com/products/autodl/j2se" version="1.4+"/>
</resources>
<resources>
<jar download="eager" href="dist/ztest17.jar" main="false"/>
</resources>
<resources locale="" os="">
<jar download="eager" href="dist/lib/swing-layout-1.0.1.jar" main="false" version=""/>
</resources>
<application-desc main-class="ztest17.Main"/>
</jnlp>

Answer 1

I receive the error shown below when launching a Java
application and cannot figure out where to begin with
debugging. There are a number of problems, potential problems,
redundancies and illogicalities in that JNLP file.
...It was developed under Netbeans 5.0. Uh-Huh. I am coming to recognise those
(damnable) NetBeans JNLP files.
You can recreate the error I don't think I need to, your error output and JNLP
file are quite instructive..
...by launching this
application:
http://www.mikenaglich.net/ztest17.jnlp
Error text and JNLP file follow. I am really puzzled
and would appreciate any help. Thanks.
Error Text
========
The XML page cannot be displayed
Cannot view XML input using style sheet. Please
correct the error and then click the Refresh button,
or try again later.
The system cannot locate the object specified. Error
processing resource
'http://www.netbeans.org/jnlp/DTD/jnlp.dtd'.
1) Whenever you see a message from Java,
JavaWS, or an application saying words the the
effect of 'cannot find..', try checking the URL of the
resource in a browser. If a browser comes
up '404' (not found), then the Java tool or app.
will be unable to access it either.
That is the first and fundamental problem with that
JNLP. The DOCTYPE element is not strictly needed
in a JNLP, and I would recommend removing it entirely
rather than try and hunt down any NetBeans DTD.
With the way NB writes JNLP's, I would not trust
a DTD written or controlled by them, in any case.
App JNLP File
===========OK.. I recommend replacing the current JNLP
with the one below, here is a summary of the
changes I made..
- removed DOCTYPE line with reference to '404' DTD
- compacted resource elements, removing empty attributes
- changed ztest17.jar to main='true'
- removed redundant 'download="eager"' attributes as well
as main="false" and version="" from swing-layout.. jar element
- removed broken(?) <icon> element and empty <description>
- changed homepage href to relative
Some of them are guesses, but I'd give it a 90%+
chance of working, if written like this.
<?xml version="1.0" encoding="UTF-8"?>
<jnlp codebase="http://www.mikenaglich.net" href="ztest17.jnlp">
<information>
  <title>ztest17</title>
  <vendor>Mike Naglich</vendor>
  <homepage href="/"/>
  <offline-allowed/>
  <shortcut online="true">
    <desktop/>
  </shortcut>
</information>
<resources>
  <j2se href="http://java.sun.com/products/autodl/j2se" version="1.4+"/>
  <jar href="dist/ztest17.jar" main='true' />
  <jar href="dist/lib/swing-layout-1.0.1.jar" />
</resources>
<application-desc main-class="ztest17.Main"/>
</jnlp> Note that a glance inside the ztest17.jar supports
it contains a manifest file tat specifies the main class,
so it might be possible to remove main='true'
altogether - best not for the moment, though.