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From Mike Matrigali <mikem_...@sbcglobal.net>
Subject Re: Potentially removing compatibility requirements for shared code
Date Fri, 18 Nov 2005 22:03:37 GMT
Due to the embedded nature of derby, and if it were to become popular I
believe that it may be common for users to wish to run multiple 
instances of Derby in the same VM (actually I don't think users will
know anything about it as they will be running some other piece of
software that has chosen Derby so that they could seamlessly run
a database without letting the user know anything about it).  I
know with Cloudscape there were cases of at least 4 instances of
Cloudscape in a given JVM, all layered within products that did
not anything about the other pieces of software.

Now we can pile hurdles in front of the users or the applications
embedding Derby and that will work for some number.  But any hurdle
will mean less adoption of Derby.

I understand that the compatibility stuff is a pain, but if Derby
can solve it then it make it stand out.  Just as the soft/hard
upgrade stuff is a pain to developers but will enable it's use in
some applications that otherwise could not adopt Derby.

David Van Couvering wrote:
> Hi, all.  I've been reading Kathey's email about her work on a
> classloader that can isolate Derby instances (and the trouble she's been
> having with system properties), and I'd like to pose something to the list.
> I am thinking (and I think Kathey's thinking along the same lines)
> perhaps there is a way to either transparently or with very little work
> from the user (e.g. a property on the connection URL) make it possible
> to isolate loading of Derby classes using some kind of specialized
> classloader.
> *If* I can figure something out, this could remove the requirement to
> support backward and forward compatibility, which is a serious albatross
> right now around shared code.
> Is this work that you think is valuable, or am I chasing a red herring
> (lots of bird analogies in this email).
> Thanks,
> David

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