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From "Andrew John Hughes" <gnu_and...@member.fsf.org>
Subject Re: harmony class libs and GNU Classpath
Date Fri, 12 Sep 2008 17:25:56 GMT
2008/9/12 Sean Qiu <sean.xx.qiu@gmail.com>:
> 2008/9/12 Anders Kristensen <andersk@cisco.com>:
>> Hi,
>> I'm new to the Harmony project and was wondering about the relationship
>> between Harmony and the GNU Classpath project, e.g.:
>>  - How much (if anything) of the Harmony class libraries come from the GNU
>> Classpath project?
> None,  Harmony is delivered with Apache License V2 [1], while GNU
> Classpath is delivered with GPL.
> These two licenses are incompatible, so they can't adopt each other's
> code at all.

Wrong.  GNU Classpath is licensed under the more liberal GPLv2 +
Classpath exception.

'As a special exception, the copyright holders of this library give
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version.'

IANAL, so I will not comment any more on their respective
compatibility, suffice to say that
I think it would have been possible, given time and effort from those involved.

There was much talk about collaboration between the two projects when
Harmony started,
but problems arose.  See the mailing list archives for the details,
but from my perspective
I don't believe the new Harmony project did much to engender a good
relationship with the
existing GNU Classpath project.

>>  - Do the two efforts continue in parallel or is one emerging as being more
>> likely to flourish and attract future development?
> I don't familiar with GNU Classpath, but I know Harmony gradually
> becomes mature.
> Harmony has clear high level roadmap and detailed close goals [2].
> Harmony has a active community which comprises of active committers
> and contributors [3].

OpenJDK is likely to attract the most future development.  Most former
GNU Classpath
hackers now work on this, under the IcedTea banner.  Some GNU
Classpath development
continues; there should be a 0.98 release soon, which will form part
of GCJ 4.4 as well.

I definitely think there still should be an independent (i.e. non Sun)
implementation of the JDK,
if just to prove it's possible.  It's possible to take a view of
OpenJDK as being an attempt by Sun
to slow such a development; while their RI has been released under the
GPLv2 + Classpath exception (thus
solving the problem of a Free complete JDK), the TCK and the standards
process remains closed.

>>  - If they're both active, which one is more complete?
> You can get the api diff from here[4], though the data may be out-of-data.
> Harmony has been improved quite a lot during this period.

The GNU Classpath data here is also outdated.  Please refer to the comparisons
on the front page of our website:
http://www.gnu.org/software/classpath which are
live and updated multiple times daily.

> What's more, Harmony has a virtual machine implementation as well
> which is called DRLVM [5].
> And Harmony classlib could be integrated with IBM VM or  Jrockit VM.

GNU Classpath arose in the late 1990s through a merging of existing
class library
efforts in VMs such as GCJ and Kaffe, to become solely a class library project
used by multiple VMs.  One of the advantages of GNU Classpath over the other two
is a more proven VM interface as a result.  It supports GCJ (AOT compilation),
JikesRVM (Java-based), JamVM, Kaffe, CACAO and IKVM.net (.NET-based)
among others
and has a clear well-specified Java-based interface.  All those
mentioned are Free software.
Note that the latter two now use OpenJDK (CACAO as well as GNU
Classpath, IKVM.net instead of).

For Harmony, your list only includes two Free VMs: DRLVM (which it was
developed for)
and JikesRVM, support for which is still nascent.  Both IBM's and
JRockIt are proprietary.

> Correct me if I am wrong :)

I think I did, where you were ;)

>> Thanks,
>> Anders
> [1] http://harmony.apache.org/license.html
> [2] http://harmony.apache.org/roadmap.html
> [3] http://harmony.apache.org/contributors.html
> [4] http://www.kaffe.org/~stuart/japi/htmlout/
> [5] http://harmony.apache.org/subcomponents/drlvm/index.html
> --
> Best Regards
> Sean, Xiao Xia Qiu
> China Software Development Lab, IBM

Andrew :-)

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