exist-development

[Exist-development] Licensing for XQuery grammar (ljo branch)

[<fi...@us...>]

I'm concerned about some files which were recently committed to the ljo 
branch:
http://exist.svn.sourceforge.net/exist/?rev=10949&view=rev

The files were released under the Apache 2.0 license, which is not compatible 
with the LGPL v2 (or 2.1). The rest of the code is licensed under LGPL v2 (or 
later).

I am not a lawyer, so this is not a legal analysis, but my impression is that 
changing the license for eXist to LGPL v3 (or later) is an option because v3 
is compatible with Apache 2.0. Or, a more difficult approach would be to 
release eXist-ljo under LGPLv2.1 or later, and eXist+ljo under LGPL v3 or 
later. Another option may be to ask the copyright holder(s) on the xqgrammar 
software (Nikolay Ognyanov, et al.?) to release their code under a dual 
license including LGPL 2.1.

And I guess yet another option would be to find or write another compatible 
xqgrammar.

Does this make sense?
Luigi

Re: [Exist-development] Licensing for XQuery grammar (ljo branch)

[Wolfgang M. <wol...@ex...>]

> I'm concerned about some files which were recently committed to the ljo
> branch:
> http://exist.svn.sourceforge.net/exist/?rev=10949&view=rev

This is an experimental branch and personally I'm not yet sure what
benefits and risks it would have to replace our own grammar. It is a
major change which has to be considered carefully. The main problem we
faced during the past year was to migrate our own lexer/grammar from
ANTLR 2 to 3. Among other things, ANTLR 3 would allow us to provide
better error messages (e.g. to finally fix the annoying "expected xyz
found null" messages). Obviously Nikolay managed to use ANTLR 3 to
cover all of XQuery. That's an advantage. But instead of reusing his
grammar, we could also try to learn from what he did.

Anyway, the grammar alone doesn't help us much: we would need to
extend it to generate an abstract syntax tree as input for our own
tree parser (which then generates the executable XQuery expression
tree). We cannot just reuse the code: we need to extend and annotate
it. This makes the license issue more problematic.

Well, I guess we should just get into contact with Nikolay (if this
hasn't happened already) and ask him about his opinion.

Wolfgang

Re: [Exist-development] Licensing for XQuery grammar (ljo branch)

[Leif-Jöran O. <lj...@ex...>]

Den 2010-01-06 21:17, Wolfgang Meier skrev:
>> I'm concerned about some files which were recently committed to the ljo
>> branch:
>> http://exist.svn.sourceforge.net/exist/?rev=10949&view=rev
>
> This is an experimental branch and personally I'm not yet sure what
> benefits and risks it would have to replace our own grammar. It is a
> major change which has to be considered carefully.

Yes I have been turning this question back and forwards, outside and in 
for the last two days since Dmitriy added the xpath grammar part and 
wanted us to use the full xquery version.

> The main problem we
> faced during the past year was to migrate our own lexer/grammar from
> ANTLR 2 to 3.   Among other things, ANTLR 3 would allow us to provide
> better error messages (e.g. to finally fix the annoying "expected xyz
> found null" messages). Obviously Nikolay managed to use ANTLR 3 to
> cover all of XQuery. That's an advantage. But instead of reusing his
> grammar, we could also try to learn from what he did.

I have been leaning more and more towards this today while working up 
some steam for getting on with the tree parser for this xqgrammar 
lexer/parser. The antlr3 inmaturity has bitten us hardest in the tree 
parser and that is still where most of our needed action is located. The 
general idea and direction of our own rewrite and Nikolaj's is not that 
different.

> Anyway, the grammar alone doesn't help us much: we would need to
> extend it to generate an abstract syntax tree as input for our own
> tree parser (which then generates the executable XQuery expression
> tree).

> We cannot just reuse the code: we need to extend and annotate
> it. This makes the license issue more problematic.

I totally agree. This will get quite messy with our needed extensions.

> Well, I guess we should just get into contact with Nikolay (if this
> hasn't happened already) and ask him about his opinion.

Agreed.

Leif-Jöran

Re: [Exist-development] Licensing for XQuery grammar (ljo branch)

[Leif-Jöran O. <lj...@ex...>]

Hi Luigi,
I agree with your analysis. This has to be discussed. I numbered the 
options below for simpler reference.

Den 2010-01-06 20:32, fi...@us... skrev:
> I'm concerned about some files which were recently committed to the ljo
> branch:
> http://exist.svn.sourceforge.net/exist/?rev=10949&view=rev
>
> The files were released under the Apache 2.0 license, which is not compatible
> with the LGPL v2 (or 2.1). The rest of the code is licensed under LGPL v2 (or
> later).
>
> I am not a lawyer, so this is not a legal analysis, but my impression is that

1> changing the license for eXist to LGPL v3 (or later) is an option 
because v3
> is compatible with Apache 2.0.

2> Or, a more difficult approach would be to
> release eXist-ljo under LGPLv2.1 or later, and eXist+ljo under LGPL v3 or
> later.

3> Another option may be to ask the copyright holder(s) on the xqgrammar
> software (Nikolay Ognyanov, et al.?) to release their code under a dual
> license including LGPL 2.1.

We could always start with investigating 3 if noone objects.

> And I guess yet another option would be to find or write another compatible
> xqgrammar.

Yes, I was on my way in the original antlr3 branch.

Cheers,
Leif-Jöran

Re: [Exist-development] Licensing for XQuery grammar (ljo branch)

[Dmitriy S. <sha...@gm...>]

On Wed, 2010-01-06 at 21:42 +0100, Leif-Jöran Olsson wrote:
> 3> Another option may be to ask the copyright holder(s) on the
> xqgrammar
> > software (Nikolay Ognyanov, et al.?) to release their code under a
> dual
> > license including LGPL 2.1.
> 
> We could always start with investigating 3 if noone objects.

I'm in contact with Nikolay Ognyanov & we did exchange some ideas. I do
believe that license will not be big issue (other world will be
resolved). All we need is tree parse to prove that it's right way.

By the way, I vote for LGPL v3, because we do have Apache License
Version 2.0 staff (example: commons-*.jar & so on).
 
-- 
Cheers,

Dmitriy Shabanov