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From "Geir Magnusson Jr." <ge...@apache.org>
Subject Re: The Classpath VM interface. (Please read)
Date Tue, 07 Jun 2005 12:20:28 GMT

On Jun 6, 2005, at 11:38 PM, Sven de Marothy wrote:

> On Tue, 2005-06-07 at 12:36 +1000, Peter Donald wrote:
>> [A] Suns rt.jar and derivatives (such as IBMs) class libraries
>> [B] GNU Classpaths class libraries
> [..]
>> In an ideal world Harmony VM would be able to use either [A] or [B]
>> with a small adapter layer. Much like MMTk can be used in multiple  
>> VMs
>> with a small adapter layer.
> If you have downloaded Harmony, which intends to be a full JDK  
> including
> a VM and class library, why would you want to be able to use that  
> with the
> class library from a different JDK?

Because users aren't just end users writing code.  We expect  
participants here (and consumers of the output) to be people who need  
to use Apache Harmony as a core for their VM distribution to avoid  
having to re-do all the work that we do, upon which they will add  
whatever features they want.  This could be a new class library  
tailored for some specific purpose, an augmented or modified class  
library, etc.

> Disregarding the illegality of distributing such a combo, there is  
> no good
> practical reason for wanting that either.

There are quite a few good practical reasons, and remember, the above- 
mentioned people would simple get their own TCK license and certify  
their disto if they wanted to distribute.  We provide under the  
Apache License (and compatible) - what people do with the software  
downstream isn't our business, nor something we willingly restrict.

(That said, we encourage compatibility as good for the whole Java  

>> It seems unlikely that either [A] or [B] is going to invest the  
>> time in
>> trying to develop a common VM interface because they are not  
>> interested in
>> facilitating reuse of the alternative.
> Java specifications are created by the JCP and not Sun. This issue
> should be raised there before jumping to conclusions like that.

Well, that's an interesting idea - why don't we try to develop a VM/ 
classlib interface and bring to the JCP?  :)

Sven, ever want to be a spec lead?

> And as a Classpath developer (but speaking for myself), I feel that we
> would be quite happy to use a common VM interface, if there was a  
> such a
> specification. Unless of course if it was so extremely bad, that  
> all the
> Classpath-using VMs refused to use it. Which I think is unlikely.
>> So it is probably going to be up to a third party like Harmony to
>> investigate a common VM layer.
> Harmony is not a third party. We're all in this together. However,
> Harmony can help solve this. Apache has a good standing in the JCP,  
> and
> thus better chances than most for getting this specified.

I'd rather us get it worked out here, and then bring to the JCP.

>> I am not sure it is going to be possible either technically or  
>> politically but it
>> is an interesting idea and worth trying.
> The politics are easier when you work from an open mind.
> /Sven

Geir Magnusson Jr                                  +1-203-665-6437

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