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Hi,

I'm a web developer and I require a generic PHP CALDAV library to be used on a proprietary project that I am working on.

I understand that DAViCal is release under GPL which means there are conditions on which it can be included in other pieces of software.

I wondered if it would be acceptable to the DAViCal community if I were to modify it to be a more generic PHP library, and then release that under GPL, but then use the generic library within the proprietary project for the company I work for.

I believe in open source software and have released many programs to the public:
http://code.google.com/p/limegreen/
http://code.google.com/p/randr/
http://code.google.com/p/jamesdlow/

However, I hope you can understand that some companies don't allow release of their whole projects, so I can't for this one. I want to only use parts of DAViCal if we can come to an agreement on terms that are acceptable to both parties, so please let me know if you think this may be possible and if you need more information.

Thanks,
James

On Tue, 2010-07-27 at 01:00 +0800, James David Low wrote:
> Hi,
>
> I'm a web developer and I require a generic PHP CALDAV library to be
> used on a proprietary project that I am working on.
>
> I understand that DAViCal is release under GPL which means there are
> conditions on which it can be included in other pieces of software.
>
> I wondered if it would be acceptable to the DAViCal community if I
> were to modify it to be a more generic PHP library, and then release
> that under GPL, but then use the generic library within the
> proprietary project for the company I work for.

I don't mind, although such a project could well end up as a fork,
ultimately - it would very much depend on how such libraries would be
interfaced.

There has been some significant encapsulation work done over the last
few versions, also, which I would be happy to see continued.


> I believe in open source software and have released many programs to
> the public:
> http://code.google.com/p/limegreen/
> http://code.google.com/p/randr/
> http://code.google.com/p/jamesdlow/
>
> However, I hope you can understand that some companies don't allow
> release of their whole projects, so I can't for this one.

The GPL only requires the code to be released to those customers who
have bought the right to run it, though of course they may not be
restricted from redistribution - a right which I like to see preserved,
since it enables them to easily arrange alternative coding support
should they run into problems with the author of the proprietary
application they are buying (e.g. their unplanned demise :-).


> I want to only use parts of DAViCal if we can come to an agreement on
> terms that are acceptable to both parties, so please let me know if
> you think this may be possible and if you need more information.

It may be possible, but I'd need more information. There are other ways
that could also be possible, such as dual licensing under commercial
terms, but that might be non-trivial to arrange.

Cheers,
Andrew McMillan
--
------------------------------------------------------------------------
http://andrew.mcmillan.net.nz/ Porirua, New Zealand
Twitter: _karora Phone: +64(272)DEBIAN
The truth is rarely pure, and never simple. -- Oscar Wilde
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Hi Andrew,

The project this will be used in is a free website offering some of its service over CalDav. My intention is this:
1) Modify DAViCal to be more generic and release that code under GPL.

2) Use the modified code as a library in a larger piece of proprietary software, linking via call backs.

Additional question, do you see any difference between linking via call backs and via inheritance in terms of licensing?

Thanks,
James


I got individual replies from Michael Rasmussen and Armin and sent them this reply, Armin's txt is quoted within mine.
> Hi Michael and Armin,
>
> Firstly let me thank you both for replying and letting me know your thoughts. Also please do CC anybody else you think should be involved in this discussion.
>
>> What would be legal: You can license software you wrote with any
>> license you want (as long as you have all the rights - meaning
>> specifically: your code isn't based on any GPL code).
>
>
> That would mean not using DAViCal?
>
>> And you can
>> define a license allowing the usage in proprietary licenses with
>> the condition that the software is also licensed as GPL.
>
>
> Well if I did use it, I would release the generic CALDAV library under GPL, but not the code that would use it. I think it comes down to how you see us able to use that generic library within a proprietary application. I see the issues as:
>
> 1) Is using a PHP file as a library analogous to a public facing proprietary program which runs on a Linux computer but interacts with a GPL library on that computer.
>
> 2) In order for it to use the library, it will have to pass some kind of call back to it. Is this an acceptable form of (1)
>
> Let me know what you think,
> James



In addition Armin replied this:
> If I understand you correctly:
> * You want to use and modify the CALDAV library. You modifications
> of CALDAV library clearly will always have to be licensed as GPL.
> * You are writing a completely separate software with a proprietary
> license, linking to the library. This does not violate GPL as long
> as you don't use any code directly in your software.
>
> If I understood you correctly, you don't need a specific license from
> Michael, you just have to publish your CALDAV library modifications
> as GPL.
>
> Armin


Thanks,
James
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