Excellent question. To be honest, I didn't know that we ended up with
different "subclassing" behavior when using a 1.5 JVM vs a 1.6 JVM.
In Sun-ish 1.6 VMs, we can automatically register a class transformer
on the fly (see InstrumentationFactory). I don't remember all the
subtleties of the configuration and the implications on what we can
do, but there are definitely differences in the pathways, as we can
directly mutate code blocks in 1.6 environments (but maybe we can't
add fields and methods?).
Has anybody spent any cycles on that approach?
I haven't investigated one way or the other. I believe that there's a
table somewhere in the docs that spells out the differences between
the various approaches.
-Patrick
On Dec 9, 2008, at 7:19 AM, Kevin Sutter wrote:
Hi Patrick,
On Tue, Dec 9, 2008 at 1:11 AM, Patrick Linskey <[EMAIL PROTECTED]>
wrote:
What is the impact of your proposal on people who are using Sun-ish
1.6
VMs, which have on-the-fly class redefinition support?
Put another way, to what extent have you considered the differences
in
flakiness between the 1.5-friendly subclassing approach and the 1.6-
needing
redefinition approach?
Excellent question. To be honest, I didn't know that we ended up with
different "subclassing" behavior when using a 1.5 JVM vs a 1.6 JVM. I
thought the reported problems were equally applied to both JVM
versions. Do
we know that the 1.6 redefinition capabilities avoid the reported
problems?
Has anybody spent any cycles on that approach?
Maybe something to think about is to turn off the subclassing
support for
the 1.5 JVM and leave the class redefinition support on for the 1.6
JVM? I
really don't know enough about these alternate approaches to make
that kind
of statement at this point.
Other thoughts?
Thanks,
Kevin
-Patrick
On Dec 4, 2008, at 4:25 PM, Kevin Sutter wrote:
Hi,
This is a tough decision, but one that I think we need to make.
If you
have
been following the dev mailing list, there have been several
discussions
[1]
and JIRA Issues [2] about the fallback enhancement by subclassing
that we
put in place back in the 1.0.0 timeframe. Although we succeeded
in making
the initial out-of-box experience easier for the newbie OpenJPA
developer,
we also masked the need for true enhancement for production
usage. So,
unless we deem that this subclassing enhancement is critical to
OpenJPA's
acceptance and usage, I propose to turn this option off by
default. The
ability to do this subclass enhancement will still be available
via the
openjpa.RuntimeUnenhancedClasses property, but the default will
now be
either "warn" or "unsupported" instead of "supported". I would
like to do
this for trunk for sure and possibly the 1.3.x branch as well.
Please
vote
accordingly. Thanks for your input. Write-in comments are also
welcome.
[ +1 | 0 | -1 ] Turn off subclass enhancement in trunk
[ +1 | 0 | -1 ] Turn off subclass enhancement in 1.3.x
I am not proposing to turn it off in the other branches since
those are
not
active development streams, but rather service streams. We
shouldn't
introduce a change like this into a customer's service stream.
That is,
for
a customer to get 1.0.4 with this option turned off would be a
surprise
since they would only be expecting fixes. Fine line in this case,
but you
get the picture.
Thanks,
Kevin
[1]
http://n2.nabble.com/Re%3A-Foreign-key-field-doesn%27t-get-populated-in-descendant-class-in-Join-Inheritance-td1574111.html#a1574493
[2] http://issues.apache.org/jira/browse/OPENJPA-651,
http://issues.apache.org/jira/browse/OPENJPA-650,
https://issues.apache.org/jira/browse/OPENJPA-293
--
Patrick Linskey
202 669 5907
--
Patrick Linskey
202 669 5907
