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From Kathey Marsden <kmarsdende...@sbcglobal.net>
Subject Re: VOTE: Principles of sharing code
Date Wed, 02 Nov 2005 21:14:26 GMT
David W. Van Couvering wrote:

> This is correct, except I think limiting it to "classpath" may cause
> confusion in some environments.  See for example Bryan's struggles
> because he had a Derby jar file in $JAVA_HOME/lib/ext, which takes
> precedence over the classpath.
>
> You might say something more general like "ensuring that the higher
> revision level jar is first in the order that classes are loaded (e.g.
> by placing it first in the classpath) will make the functionality and
> bugfixes from the higher revision level available"
>
good point

> Also, it's possible that the higher revision functionality is still
> visible *if* it's from a package that doesn't exist in the older
> revision of the common code.

Since most users are not really up on what classes exist in the Derby
implementation,  I just punted with "may not be available" as in don't
bank on it.

> Also, you don't talk about upgrade scenarios, where the bugfix is
> there, but then someone upgrades and all of a sudden the bugfix is gone.  

Yes, that one is a bit scary and worthwhile making people aware that it
might happen, but assuming this change is approved, it mostly seems to
me I need to get folks focused on the immediate workaround  which is to
get the highest rev jar loaded first, and hopefully make headway on the
long term application isolation education issue which as Rick mentioned
is already an issue (albeit a less mysterious one) for multiple embedded
applications/components  running in the same JVM.    But first I better
educate myself on class loaders, which apparently won't be a small task.
 
http://mail-archives.apache.org/mod_mbox/www-women/200510.mbox/%3c200510281719.13686.bloritsch@d-haven.org%3e

Thanks for updating the  user impact on the Wiki page
http://wiki.apache.org/db-derby/SharedComponentVersioningGuidelines.  I
think the description of user impact, while less attractive is much more
accurate now and  I can  believe it.

Kathey




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