The binary is here: WebStartEx.jar (July 19, 2003) The license is GPL 2.0.

To use it, you have to follow some steps:
- Your main class must be in an executable jar file.
- Create one or more jar files of your whole program (think wisely so that if a part of the project is to be updated, few jar files need to be updated) So you jar the jar files and the external resources if any (they might be created by the program itself)
- In each jar file, add an empty file called "webstartex.remove" or "webstartex.keep" depending on whether the content of the original jar file should be removed. Keeping the content is relevant only if the jar file is used by several Web Start applications.
- Sign the resulting jar files.

Let's consider the jar files are "MyAppAr1.jar" and "MyAppAr2.jar", with the unjared executable jar file being "MyApp.jar" residing in "MyAppAr1.jar". Then in the JNLP file, add the folowing:

<resources>
  <jar href="WebstartEx.jar" main="true" />
  <jar href="MyApp1Ar_cache.jar" download="lazy" />
  <jar href="MyApp1Ar.jar" />
  <jar href="MyApp2Ar.jar" />
</resources>
<application-desc main-class="chrriis.webstartex.WebstartEx" >
  <argument>MyApp.jar</argument>
  <argument>...parameter1 of MyApp if any...</argument>
  <argument>...parameter2 of MyApp if any...</argument>
  <argument>...etc...</argument>
</application-desc>

Note: the name of the cache must be defined as a lazy download (though nothing will get downloaded) and must be constructed using the name of the jar that contains the executable jar.

Note: you can change the name of the files "webstartex.remove" and "webstartex.keep", if you set the system properties "webstartex.remove" and "webstartex.keep" with the appropriate file names.