Re: How often does a Java Web Start application update itself?


"Andrew Thompson" <seemysites@xxxxxxxxxxx> wrote in message
news:u9d%e.3434$U51.2339@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Oliver Wong wrote:
>
>> When the application is first "installed", JWS will offer to create
>> desktop icons. So the documentation makes it sound like if the user
>> launches the application using these desktop icons, then the application
>> will be "launched offline", meaning no checks will be made for an updated
>> version.
>
> Nope. As I understand, and have experienced JWS.
> The app. is checked for a new version every time you
> start it and an internet connection is available,
> irrespective of what launches it (menu, desktop
> icon, link to JNLP file).
>
> If the *splash* image changes, it will not update
> for the user till the *next* time the app. is launched,
> but as far as I undersstand, the time stamps of the classes
> are checked before JWS decides whether to upload the local
> classes immediately, or update them first (so the end
> user always gets the lates version of the app.).
>
> If an internet connection is not available, and the app.
> is marked for 'offline' use, the local copy is launched.

On my development machine, I'll decide to make a release, so I export
the code to a JAR file, sign it, and then upload it to the webserver. Then,
while still connected to the Internet, when I run the application from the
desktop shortcut created by JWS, I'll see the old version start up. I had
assumed maybe it only checks once every 24 hours or something. I can "force"
it to get the latest version by re-using the JNLP file from the webserver.

>> What I want is:
>>
>> * Give the user the opportunity to run the application without being
>> connected to the Internet.
>
> specify offline allowed

Done.

>> * Let the user run the application using the desktop shortcuts for
>> their convenience.
>
> It is up to the end user* and how they have JWS configured
> as to whether they get a desktop icon.

Yes, I don't want to FORCE the creation of icons. I just meant that I
don't want, as a solution, to force the user to always re-download a JNLP
file from the webserver. This solution solves the "force the app to check
for updates" problem, but it violates the requirmeent of letting the user
run the app from a desktop shortcut.

>> * If the user *IS* connected to the Internet, to periodically check
>> for update versions.
>
> How about 'each start-up'?

Good enough. It's just that my tests have so far shown that JWS tests
"never", which is not sufficiently often for my requirements.

> Hmm... that seems to have 'the right stuff' to produce the
> behaviour you desire. How big is your application?
> I could check it for you from here, but my connection
> is a bit challenged at the moment.

My code (and thus the part that changes) fits in a 130Kb JAR file. It
also depends on a JFreeChart library which is a 1.1Mb jar file, but which
never changes. So the initial download is about 1.2Mb, and every subsequent
download should be 130Kb.

But in another thread Roedy said that JWS only checks if the JNLP file
itself changed, and not the JARs. Since I've never regenerated the JNLP,
perhaps that explains why I'm not seeing my app get updated? I'm don't have
access to my development machine right now, so I can't test this theory, but
I will try it tonight.

- Oliver


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