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From Daniel John Debrunner <...@debrunners.com>
Subject Re: FAQ language
Date Mon, 11 Oct 2004 15:34:49 GMT
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Joseph Grace wrote:

> As a sidenote, this issue may be an example where what works for
> Cloudscape, does not necessarily work for Derby.  By that I mean that
> Cloudscape had the luxury of restricting which platforms it supported,
> and consequently could take shortcuts since it could exhaustively test
> for just the supported platforms.  Derby has no such luxury as
> platforms are shifting all the time, so we depend on the correctness of
> JVM's and of completeness of documentation to guarantee behavior (with
> some testing thrown in as well :-).  In any case, I think Cloudscape
> benefited from restricting platforms, whereas Derby must make do with a
> less controlled environment.  In that context of a less forgiving Derby
> platform environment, perhaps the "rws" optimization from the
> Cloudscape code is not appropriate for Derby.

Actually Cloudscape has never restricted support to a set of platforms.
It is always supported on any platform as long as an appropriate java
virtual machine was supported.

Usually to handle JVM bugs the Cloudscape team worked with the JVM
supplier and got the bug addressed. I can recall two cases where JVM
specific code was added to Cloudscape, one was for Microsoft's JView and
one for Symbian's JVM. The Microsoft case was something specific to
Jview for class loading, the Symbian was something to do with file i/o
where either the JVM spec was unclear or maybe we just wanted to get
running asap on that platform (like Derby does for MacOS).

To address the new JDK 142 file i/o optimization, Derby could switch
from asuming every 142 JVM supports it correctly, to only enabling it if
 we know the JVM supports it. Thus Sun & IBM VMs handle it correctly,
and as the community runs Derby on other VMs we could add to that list
and modify the code to enable support on that VM. If there was a simple
test program then it would be easy to ask community members to run it as
activity is seen on a new JVM.

Dan.

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