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Webstart if the application version downgraded

Suresh Reddy O
Greenhorn

Joined: Sep 12, 2010
Posts: 2
In my project i have a web start application. That is working as expected in upgrade scenario (i.e if i upgrade application version from 2.3 to 2.4, client getting 2.4), but in downgrade scenarios it is not working, (i.e if server has 2.4 version and users are using it and if we change version in server to 2.3, users are not getting 2.3 version application even if they relaunch the application).

How can i overcome this issue? Is there any solution for this? How we start find the application is updated or downgraded?

Thanks in advance.
Maneesh Godbole
Saloon Keeper

Joined: Jul 26, 2007
Posts: 10255
    
    8

Welcome to the Ranch.

Java is backward compatible. Why do you want to use an earlier version?


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Suresh Reddy O
Greenhorn

Joined: Sep 12, 2010
Posts: 2
I am not saying about java version, that is my application version. My java web start application sits in server, that server supports downgrade and upgrade facility. If user downgrade server software then server will have old version of java web start application but client machine have latest java web start application because he has accessed the application before downgrade the server, but server has old version at that point.

If user clears java cache in his machine the he can web start will download from the server, then his system will have old version application. But my requirement is if server is downgrade, then if user opens web start then he also should get the same old version of web start application.
Maneesh Godbole
Saloon Keeper

Joined: Jul 26, 2007
Posts: 10255
    
    8

My bad. I got confused between your application version and the JRE version.

Well the jnlp mechanism would compare the local version and the server version and then decide to download or not.
I dont know exactly how it does but it probably either the version specified in your manifest or the time stamp of your jar.

You can test this by
1) Recompile the old jar so it carries a newer time stamp
2) Modify the manifest to carry an incremental version number

In either case, if my thinking is correct, it would mean recompiling the jar. Maybe you want to carry these tests and share the results?
 
It is sorta covered in the JavaRanch Style Guide.
 
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