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Re: [Xen-users] Re: Does it legal to analysize XEN source code and write a book about it ?

On Mon, 2007-09-17 at 09:40 +1200, AD. wrote:
> Tim Post wrote:
> > First, Xen is free software. While it is licensed under the GNU GPL
> > License,
> > it is free software. Please stop calling it open source. "Open Source"
> > is a 
> > misnomer. For a program to be free, its source is already considered to
> > be 
> > "Open", but that is just one requisite. To also be free, you must be
> > able to
> > copy it, share it, package it and sell it yourself.
> > 
> > Some programs are open source but not free, many of them Microsoft
> > programs.
> > They have a developer network where members get a new set of CD's every
> > quarter
> > with new goodies on them that have source code included. This is open
> > source, 
> > not free. You can't share those programs or their source code, if you
> > improve the 
> > code the only people you can share your imrpovements with is Microsoft.
> Tim, while I agree with everything else you posted, your definition of 
> "open source" doesn't match my understanding. Open source doesn't just 
> mean that you can look at the source code.
> That MS example you cited wouldn't be open source, as open source also 
> requires that you are able to "copy it, share it, package it and sell it 
> yourself".
> http://www.opensource.org/docs/definition.php
> The MS license you mention (there are others) is what they call "shared 
> source". As far as I'm aware, no MS license has been approved by the OSI 
> yet.

For software to be free, its source code must be available and released
under a license that does not restrict how you (as the user) use the
source code or the program. If a program is licensed under the GNU GPL2
(or later), it is considered to be free software. The availability of
source code is a prerequisite for this, but only one prerequisite.

The GPL ensures that anyone distributing a program _must_ give you the
same freedoms that they enjoy with the program and its source code. I
could take BSD licensed code, modify it then send you binaries and
refuse to give you the source code. As long as my program advertises
that it is BSD code, I'm fine. However, BSD code is 'open source'. So is
Minix and others.

"Open" doesn't always mean "free". Xen is free software, its license
guarantees that you will always have the same freedoms with the program
and its source code that XenSource has.

Whenever you call a GPL Licensed program "open source", you fail to
mention the most important aspects of the license and by extension the
program. Then, people forget them. That is unfortunate and really needs
to stop :) With something like Xen, its really important to not discount
those freedoms. 

I was around in the free software ecosystem when GPL2 came out, not a
lot of people remember all of the problems that the license cured. If we
forget those problems, they will return.

Don't forget, the headers in most GPL programs start with :

"This program is free software;"


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