Default Open JDK

[Nick]

A vendor has pointed us to use OpenWebStart in conjunction with their product I am completely new to this. In their installation guide (largely taken from this site) they state;

"This guide describes how to install OpenWebStart with its default OpenJDK on client desktops"

In our testing I'm not seeing a default OpenJDK installed - is this still bundled in the v1.5.0 and, if so, where does it get installed to?
No JVMs are shown in JVM Manager after install. If I use "find local" it will detect an existing Java instance on the client device.

Thanks in advance.

[Stephan Classen]

yes and no,

There is a bundled JRE installed together with OpenWebStart (OWS). But this JRE cannot be used for running applications.
This is a precautionary measure as we regularly change this bundled JRE and we do not want to break any working application.

Instead OWS has a JVM Manager which can find local JREs or download JREs from the internet.
So for the default user they do not need to worry about JREs any more. Simply start the JNLP file and the JVM Manager will download an appropriate JRE.
The downloaded JREs are stored in %userhome%/.cache/icedtea-web/

[caw0001g1]

Is there any way to preinstall the JRE and prevent future downloads?

[Janak Mulani]

You can install a JRE locally and in itw-settings you can add that local JRE to OWS's list of JVMs.

You can control the download of JVMs by OWS using the Update Strategy of JVM Manager Configuration. Usethe strategy "Do not download any version" to prevent OWS from downloading any JVM. Note that in this case your local JVM should be matching the one JRE specified in you jnlps.

[KlausFriese]

Thanks for this post, I save the same question

I now did this: I added an OpenJDK 18.0.1.1 to the JVM:

ows1.png (65.35 KiB) Viewed 27802 times

Set update strategy to "Never":

ows2.png (41.54 KiB) Viewed 27802 times

Version in JNLP is 18.0.1.1:

<j2se initial-heap-size="256m" max-heap-size="768m" version="18.0.1.1"/>

Result: Warning in logfile:

[ITW-CORE][2022-08-18 10:26:28.059 MESZ][WARN ][net.sourceforge.jnlp.Parser] Warnung: Die angeforderte JRE „18.0.1.1“ stimmt nicht mit der vorhandenen JRE „1.8.0_332“ überein

And an Exception:

[ITW-CORE][2022-08-18 10:26:31.295 MESZ][DEBUG][net.sourceforge.jnlp.runtime.Boot]
Exiting Boot.mainWithReturnCode() exceptionally
java.lang.UnsupportedOperationException: The Security Manager is deprecated and will be removed in a future release
at java.base/java.lang.System.setSecurityManager(System.java:416)
at net.sourceforge.jnlp.runtime.JNLPRuntime.initialize(JNLPRuntime.java:266)
at net.sourceforge.jnlp.runtime.Boot.runMain(Boot.java:258)
at net.sourceforge.jnlp.runtime.Boot.mainWithReturnCode(Boot.java:132)
at net.sourceforge.jnlp.runtime.Boot.main(Boot.java:114)

Any tipps what we need to change? Does it work with OpenJDK 18.0.1.1?

[Janak Mulani]

OWS is not working when the Jnlp application is run with JDK 18.

OWS is using the class SecurityManager which seems to have been removed from JDK 18.

https://docs.oracle.com/en/java/javase/ ... nager.html

We will investigate this.

Thanks for pointing out this error.