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On Nov 8, 2009, at 12:42 PM, vincent wrote:
Le 8 nov. 2009 à 18:33, Ty Sarna a écrit :
Okay, it can be no more than a voyage back in time to the
aforementioned episode – so, is there any estimation as to the
percentage of Sun code in today's NetBSD ZFS port?
What does that have to do with anything? It could be 100% NetBSD
code and that wouldn't change anything as far as patents.
I am not sure about this. I think you can't patent a concept, but
you could patent an implementation. For example, in the electronics
field, you maybe can patent a type of high-quality oscillator, but
you cannot claim any property on a different implementation
achieving the same goal. If you can code from scratch a FS with the
same functionalities as ZFS, I don't figure out how you could be
liable to patent suing.
That's not the way patents work. What you've described is more like
copyright, where the particular expression of the concept is
protected. With patents, it's the concept itself -- but details matter.
Let's consider the case of the famous (and now-expired) RSA patent: http://www.google.com/patents/about?id=daEsAAAAEBAJ&dq=4,405,829
. Fundamentally -- and I believe this is true throughout the world,
though what can be patented differs in different jurisdictions -- a
patent consists of two parts, a description of the invention and
"claims". The description is just that: it describes how the
invention works. A patent is basically a deal between the government
and an inventor: the inventor describes the idea in sufficient detail
that others can replicate it, learn from it, etc.; in return, the
government grants a limited-term monopoly on the *idea*. Precisely
what is protected is described by the claims. You infringe a patent
if you build something that contains all elements of any one claim.
Thus, if you look at claim 1 of the RSA patent, to infringe you'd need
a system with a communications channel, an encoder that worked
according to that description, and a decoder that worked according to
its description. If you built a system that had no communications
channel, you wouldn't infringe claim 1. However, you might infringe
claim 37, which doesn't speak of a channel.
There's a lot more I won't go into, like the "doctine of
equivalents". The net, though, is to the extent that the patent is
valid in jurisdictions of interest, you can't evade it by changing
code; you probably have to change functionality.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
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