[Qt-interest] Qt Mysql Plugin and LGPL

[Kendall Bennett]

This is still terribly confusing. If Sun went to the trouble to have this FOSS exception clause in there, and they INCLUDE the LGPL as a license that is compatible with the FOSS exception, it seems to me it would be a whole lot simpler if the MySQL client libraries were simply licensed under the LGPL also.

So consider this. Given the FOSS exception, it allows the QSqlMysql module to be licensed under the LGPL, since it is compatible. So then a developer building a proprietary application is using Qt under the LGPL license. Does that mean the proprietary program is allowed to use the MySQL client libraries via the LGPL'ed QSqlMysql module using the Open Source MySQL client libraries? Or does the developer have to spring for a proprietary license for MySQL (and I won't touch on how confusing getting one of those is, or used to be).

I think it is clear that Qt licensed under a proprietary license is not compatible with the GPL licensed MySQL client libraries, so if you use a proprietary license for Qt, the only option would be a proprietary license for the MySQL client libraries. At least that is how I read it.

Things get even more murky when you consider projects like PHP. PHP is completely open source, so it can use the MySQL client libraries under the GPL license I think (or the FOSS exception anyway). Then if you write PHP code that uses the MySQL client libaries via the PHP scripting language, is the PHP program itself infected by the GPL MySQL client libraries, because the PHP MySQL API's are kind of like a library interface to the PHP scripts?

In the case of PHP programs it gets even more complicated because most PHP scripts run on a web server. So who is the user of a PHP script anyway? Is the user the sys admin who installed the script on the web server, or is the user someone who connects via an HTTP socket to the web server via a browser? Where do you draw the line?

For this reason I never use the MySQL client libraries in our non-Open Source code at all (except via PHP). Instead I use XML-RPC or some other transport layer to connect to the database, which insulates the client desktop programs from these licensing issues.

Personally I think these FOSS exceptions just complicate everything, and stuff should either be GPL, and not allow for proprietary development, or LGPL, and allowed (assuming you meet the requirements of the LGPL).

Regards,

Kendall Bennett, CEO
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________________________________
From: "Vincent L. Damewood" <lists at damewood.us>
Date: Fri, 10 Jul 2009 09:52:46 -0700
To: <qt-interest at trolltech.com>
Subject: Re: [Qt-interest] Qt Mysql Plugin and LGPL

On Thu, Jul 9, 2009 at 4:41 PM, Thiago
Macieira<thiago.macieira at trolltech.com> wrote:
> Benjamin Sonnemann wrote:
>>My concern is following:
>>libmysql.dll is GPL, so shouldnt QSqlMysql .dll be also GPL (if used at
>>all!)  and then entire Qt plus my app?
<snip>
> That's somewhat correct. MySQL and its libraries are GPL.
<snip>
> But MySQL AB's model (before it was bought up) was like Trolltech's: show
> the source or pay up. Both were small, independent, Scandinavian companies
> before being acquired. But, like I said, only a lawyer will clarify this.

Also, like Trolltech/Qt Software, MySQL has an exception allowing
developers to use other open-source licenses in works that use the
MySQL libraries.

http://www.mysql.com/about/legal/licensing/foss-exception/

And among the allowed licenses is the LGPL. This, at least, allows Qt
Software to release QsqlMysql as LGPL. For a program that uses
QsqlMysql, there isn't going to be any problem with any of the other
open-source licenses on the MySQL exception list. If you want to go
proprietary, the folks at the Free Software Foundation says no:

http://www.gnu.org/licenses/gpl-faq.html#IfLibraryIsGPL
http://www.gnu.org/licenses/gpl-faq.html#GPLWrapper

I hope this helps.

Vincent Damewood

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