[Box Backup] Additional information for Volume Snapshot Service (Shadow Copy)

[Chris Wilson]

Hi Matthieu,

On Mon, 29 Jun 2009, Matthieu Patou wrote:

>>>>  It doesn't eliminate the issue for GPL, because Microsoft's license
>>>>  explicitly forbids linking any of their code against GPL code and
>>>>  distributing the resulting binaries. However, BSD code does not fall
>>>>  under that restriction.
>>>
>>>  I'm wondering how bacula do it with this limitation ?
>>>  Because they are compiling with this library and their code is GPL.
>>
>>  As I mentioned in another posting back in March 2009 [1], the Bacula
>>  project gets around the GPL "restriction" (actually: liberations) by
>>  adding a special clause that allows linking their GPL code with
>>  proprietary libraries.
>> 
> Achim my question was not in the sense of problems of GPL with 
> proprietary software but the opposite. Chris stated that the Microsoft's 
> license explicitly forbids linking any of their codes against GPL. First 
> I read the VSS licence and I didn't find this (but I am not a lawyer so 
> I might have misunderstood some parts), and if it's true then I am 
> wondering how Bacula manage to respect Microsoft license.

Microsoft's license says that you may not distribute any of their code 
linked to any applications that would cause their code to fall under the 
GPL (or any "Excluded License"). Because Bacula has an exception for these 
proprietary libraries, that means that it does not force them to fall 
under the GPL, so Microsoft's own license still applies, and that's OK 
under their license. They don't have a problem with linking their stuff to 
LGPL code either, for the same reason.

See the Silverlight SDK license at: 
http://msdn.microsoft.com/en-us/silverlight/bb743266.aspx . I think that 
essentially the same license applies to the VSS SDK.

Linking non-free code to GPL code is actually forbidden under the usual 
GPL for the same reason, that it would force that code to fall under the 
GPL, and if you can't distribute the entire code under the GPL then you 
can't distribute it at all. However, copyright owners are entitled to 
create a new license based on the GPL, as Bacula have apparently done, and 
to release their code under that license if they wish.

Cheers, Chris.
-- 
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