Local alternative to JNLP file?

Question

Try as I might, I can't get a JNLP file to run locally (via a double-click). It seems to be an issue of locating a jar file, even when I specify it relative to the jnlp file. I get the following error:

The field <jar>href has an invalid value: helloworld.jar

This happens even when the JNLP file is in the same folder as helloworld.jar. I've done searches and this is a consistent problem especially for people who want to package an application on a CD and use JNLP. The only Sun-provided "solution" is the ability to specify the codebase via command line, but that doesn't really help much. I don't understand why they don't assume or allow the codebase to be "." or "file://." - I tried these sorts of things in the codebase parameter of the jnlp tag (inside the file) and nothing worked.

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It is extremely convenient for me to use a JNLP file because I don't need to worry about platform detection, native libraries, or even the main JOGL jar files; I simply include this line and everything is done for me:

<extension name="JOGL" href="http://download.java.net/media/jogl/builds/archive/jsr-231-2.0-beta10/webstart/jogl-all-awt.jnlp" />

I'm hoping to find something that can do the same sort of thing. If not, I can manually (or with Ant) grab the JOGL jar files, it's not a big deal; just one of those things that JNLP does for me and I'm really going to miss.

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What is the best alternative to JNLP files, for me to use locally (i.e. double-click to run)? Is there anything so elegant or do I just need to write a shell script for Linux, a batch file for Windows, and have Ant detect and download the appropriate JOGL jars?

Answer 1

Use a manifest for your jar. There you can define the main class to start and the required libraries. See the Main-class and Class-path arguments in the manifest specification.

Answer 2

As dhiller suggests, adding a manifest to your JAR lets users run from a physical copy without network access. In addition, instead of providing a .jnlp that points to a local JAR, include a .jnlp that links to your website. That will allow users to run the latest and greatest version of your program and easily install a shortcut for future reference.

Answer 3

The JNLP system was improved with Java 6 update 10 (a while back) but it is still quite hard to debug (enabling full tracing in the Java Console, and stepping through the javaws source code.

In your situation I would go the extra mile and get it to work. Perhaps you would provide a full JNLP-file showing the problem?

Answer 4

JNLP is designed for network launching (specifically http(s)) and without a network the Java implementation must get really confused. Even mature projects like eclipse stick with the .sh,.bat option.

Answer 5

I've used a .jnlp file like this to launch Java Web Start software locally

1. specify the code base like so: <jnlp spec="1.0+" codebase="file://localhost/X:/path/to/jnlp/" href="software.jnlp">

2. list resources with relative paths: <resources> <jar href="lib/software.jar" main="true" /> <jar href="lib/softwareLibrary.jar" main="true" /> ... </resources>

3. and finally tell Web Start where it can find the software entry point inside the jar marked with main="true": <application-desc main-class="com.example.Main" />

The only thing you need to change when deploying remotely is the codebase parameter.