Does JNLP Sync up the software from the code base only at the startup?

Question

Does JNLP Sync up the software from the code base only at the startup?
There appears a Source sync every time i startup the jnlp app from shortcut.
The users of JNLP application may enable the Internet mid of the application session and fail to get the updates.
If this case repeats for a period of time, there is a good chance of the app user being denied the code update.
Is this case holds true. Does JNLP syncs with the code base only at the startup.
Please explain..
Thanks In Advance

Answer 1

Are you using versions (only 'Easy solution 2' works without)?*
No I am not using versions
Are you thinking of a background update or an on-demand update?*
background
Have you got all-permissions?
yes
Have you tried writing a small DownloadServiceListener and calling*
DownloadService.loadResource(myURLtojnlp, null, myDownloadServiceListener)*
Does anything happen?*
No. But, no problems trying it.
Easy solution 1*
If using versions and if you want an on-demand update you can launch and wait*
Runtime.getRuntime.exec("javaws -wait myURLtojnlp");*
and then you exit (need all-permissions to call exec, can try showDocument() otherwise).*
You should just have some way to know if the jnlp has changed (you could open an URLConnection and see if LastModified is after application start time).*
I am not using versions.
Easy solution 2:*
If you're just afraid of losing update, you can call BasicService.isOffline at application start, if true you set a timer that checks every 5 minutes, if you go online you call*
Runtime.getRuntime.exec("javaws -import myURLtojnlp");*
and you'll have resources updated, so they'll be good for next start (need all-permissions to call exec).*
You can call it with -wait and ask the user if he wants to restart the application*
Harder solution (here comes the bunch of code with DownloadService):*
you open an url connection to codebase, retrieve jnlp, parse it, for each resource you see if it's cached, if not:*
Solution 1: you tell the user you found updates and ask him to restart (or automatically restart after he pressed ok, with exec or showDocument).*
Solution 2: you download the resource (so that you'll have it even if user doesn't restart the app).You'd better do this in a separate Thread or have an interactive DowloadServiceListener cause service waits for download to end.*
I ll try the timer execution. Have to see weather web start puts up a downloading progress window on top of the application. I belive the DownloadService listener will be silent. I ll implement it and get back to you.
Thanks for your kind guidence.
I think your scenario is very difficult to happen, but I guess you must have your good reasons to ask.*
This scenario happens to my users as they switch on the client when the start their machine and runs for the whole morning. They switch on the internet for other purposes and shuts it down in an hour. Minimal chance of connecting the internet before the startup.
I get update towards the server through a similar timer based mechanism. I ll implement the code updates in the same mechanism.
Thanks.