David,
Thank you for the enlightening comments. However ....
David Brown writes:
> ...
> An object based repository, like GemStone/J, if it has multi-user,
> distributed, disk-based garbage collection, can manage this problem
> automatically. The product record will remain as long and only as
> long as there is a reference to it. This is a big requirement for
> reusable object models.
Imho, yes and no. Automatic GC alone is not enough to support all the
"drag this item into the trash" or "keep this object no matter what"
semantics that a good object-oriented user interface may require. As a
minimum, I want the GC algorithm to be accessible so that I can tell
the user whether a particular operation will blow away their precious
object or just unlink it from somewhere.
Think of the Unix filesystem semantics. OODBMSs with automatic GC
behave like hard links ... the last call to unlink() blows away the
file. That is _not_ the API made available to non-root users; rather,
they are given a simpler model where they can believe that "del
<file>" always blows away the file and symlinks are an "unreliable"
link to a file. And, at the API level, yes, there _is_ access to the
"GC algorithm" because stat() tells me the number of links to a file.
Hope this isn't too off-topic, but it does relate to object modeling
for long-term persistent storage.
Regards,
Ihab
--
Ihab A Awad <[EMAIL PROTECTED]>
Computational Biology Centers, Academic Health Center,
University of Minnesota. http://www.cbc.umn.edu/~ihab/
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