Question

I have recently put together a JWS application which gets it’s argument from a dynamically created JNLP file (details can be found here). It’s all good except the application ignores the argument (starts without loading the specified number) on my system (linux x86_64). It seems however that the JWS application exactly as intended on the win_64 machine of a colleague of mine. This is rather interesting as I couldn’t replicate his success on another similar win_64.

To make things more exciting, the same JWS application works just fine (in other words, doesn’t ignore the argument) when I download the JNLP file and run it by javaws on the terminal.

I have compared the java.policy and javaws.policy files and there are no differences. The JNLP file clearly gives all-permissions, and the jar files are signed all fine (which can’t be the source of the problem otherwise the application wouldn’t start, right?).

Question 1: So what could this problem depend on?

EDIT: I just managed to get proper response from a new (in this particular sense) win32 machine, without any obvious java update. Question 2 : Is there a log file for javaws on which I can check what happens, or alternatively, can I verbose the launch to a console so I can create my own custom logs?

Edit 2: By the way, I have forgotten to mention that I have also posted this question at the Oracle forums, which I should have perhaps mentioned initially as it was politely pointed out there. Anyways, there is more information on the JNLP file there on the thread, in case it might be relevant.

Edit 3: I came to think that the problem could be originating from the properties of the <jnlp> tag, upon generating the JNLP file. Originally the jnlp tag looked like this like this:

<jnlp spec="1.0+" codebase="http://mydomain/myapp/" 
    href="my.jnlp">

The problem with this is the fact that there is no my.jnlp in the the directory declared in the codebase, instead the JNLP code is created on the fly by a Perl script in the cgi-bin directory and returned as an output stream (I think). So I edited the script to generate the JNLP with the following tag:

<jnlp spec="1.0+" codebase="http://mydomain/myapp/" 
    href="http://mydomain/cgi-bin/my.jnlp">

The result of this experiment: not even the GUI started this time…
I have found a relevant thread on Oracle forums, where it was advised to define the href property in the following fashion:

href="script.jsp?<%=request.getQueryString()%>">

which unfortunately doesn’t solve my problem.

Question 3: Could this modification be applicable to my situation as well? In that case how? If not any insights on what might be causing the problem would be seriously appreciated as I am really at a stalemate on my work right now

Answer 1

After two weeks of wrestling with the JNLP file syntax and my CGI script, I think I finally found the crux of the problem. I am noting this down here (at the risk of looking pretentious enough to answer my own question) in case somebody else runs into the same problem.

The href property of the <jnlp> tag, in my case was apparently unnecessary and when removed the application started working as intended on both linux and win systems. I am not 100% sure if this is the exact reason but my understanding is that as the jnlp syntax is generated from a script and directly returned to the user instead of a jnlp file somewhere in the filesystem, the href property was pointing to a wrong place and perhaps caused some sort of a clash that is handled differently in different OS.