J2se version tag

Question

Please tell me if I have missinterpreted the functionality of the j2se version tag.
I have in my jnlp file something like this:
<resources>
<j2se version="1.4.1_02+" href="http://myServer/asp/jreinstaller.asp"/>
<jar href="mySignedJar.jar" main="false" download="eager"/>
</resources>
where the asp-file will generate a jnlp file that download and install a JRE 1.4.1_02 version...
I believe(d) that if the client machine already had jre 1.4.1_02 (or a higher version) installed - it would just fetch the wanted jar file, and if the client machine only had earlier versions of jre installed - it would download my 1.4.1_02 version before fetching the jar.
But when I test this, jws will start downloading the jre regardless of which jre(s) are already available at the client machine (whether its older or newer, i.e. 1.3.something or 1.4.2_01) . Only if the 1.4.1_02 version is already downloaded once - jws will skip attempting to download it again...
Please tell me if I'm using the j2se version tag incorrectly or if you have any other idea of why it does not behave as I thought it would.
/Matt

Answer 1

Actually, it is because the href tag is overloaded.
First: it says where to go look for a jre if non is available on the client.
Second: it uniquely identifies the jre. On any client there may be a 1.4.1 from Sun, and other ones from IBM, or Blackdown, or any other licensee.
Without an href, the jre specification is a "platform version".
<j2se version="1.4"/> means "anyones jre you find that implements the Java 1.4 specification"
In practice, Java Web Start (on windows) searches the registry for sun registered jre's, and so assigns them all the sun href (java.sun.com/products/autodl/j2se) . Also, when you ask for a "product version" Java Web Start contacts the default sun site.
It would have been beter to use a differant arg for "product version" than fo the download location such as:
<j2se version="1.4.1_02+" product="sun.com" hfre="http://jreserver.com" />
then you could ask for either a product or a platform version, either with or without an href, and attempt to download only if their was an href.
/Dietz