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Subject Dr. Mark Adler on ZLIB patent issues
Date Mon, 10 Sep 2001 19:36:16 GMT

Hello all.
This is Kevin Kiley

As promised...

Below is a cut from the second conversation I had
with Dr. Mark Adler ( co-author of ZLIB ) this weekend 
regarding some of the possible legal 'patent' issues that 
have been raised ( Ryan, Dirk, others? ) as they might relate 
to using ZLIB inside of Apache to dynamically compress the 
presentation layer content ( E.g. IETF Content-Encoding ).

The 'summary' of what Mark had to say ( full text below )
is that he has no idea if using ZLIB as the main engine
for dynamic data compression will violate generic 'lurker' patents
or not. Even Jean-loup did not specifically address these
kinds of patents with regards to ZLIB.

Dirk told Ryan he has some specific patent 'numbers' that
he is concerned about but he won't be back online 
until Tuesday so still not sure which ones Dirk was
referring to or if they are relevant.

Our own research in this area turned up a number of 
these generic 'dynamic compression of content' style 
patents, one of which is...

US5652878 - Method and apparatus for compressing data.
Issued to IBM on July 29, 1997 ( Filing date: Oct 2, 1995 ).

We had lots of highly paid attorneys looking for these
things and rendering opinions but, unfortunately, it
wouldn't do any good for me to post our findings because
( as is the case with most IP legal work ) the opinions
are not 'transferrable' in a legal sense.

The 'gist' of it is that they are probably not worth
worrying about since they are simply 'method' patents
and the 'general use' clause always kicks in in these
cases if/when there is a challenge. There is also the
'public good' clause.

We've been compressing Apache presentation layer content
all over the world for over a year now and we have not
received any 'legal' complaints from anyone but the currently
distributed mod_gzip does NOT contain or use ZLIB at all
so whether that matters or not... I do not know. I imagine
it does NOT since the 'lurker' patents are mostly of the
generic 'method' type.

If the ASF really needs to be 'severe clear' on this
I'm afraid there is no substitute for having your own
IP attorneys give you their own green light ( in writing ).

Here is all that Dr. Mark Adler had to say about the
'generic' presentation layer data delivery patent(s)...

>> At 8:45 PM EST - Saturday 9/8/01, Kevin Kiley and
>> Dr. Mark Adler had the following conversation...


>> Kevin Kiley asked...
>>The Apache group doesn't appear to have any problem with
>>the compatibility of the ZLIB/LIBPNG license with their
>>own ( more restrictive ) ASF License but a few of the
>>'patents' of ( mild ) concern at Apache are those that are 
>>floating around out there which are as generic as they can 
>>be and basically ( supposedly ) cover the delivery of any 
>>compressed presentation layer data via any communications 
>>interface. ( In other words.. all of IETF Content-Encoding ).
>>Ring any bells with you?
> Mark Adler wrote...
>No.  But patents are sneaky things, and I haven't spent any time 
>looking for the lurkers out there.  Jean-loup spent quite a bit of 
>time reading patents to make sure that the zlib deflate 
>implementation did not violate any (and there were some that we had 
>to skirt, where for example the level 1 compression in zlib could be 
>faster were it not for a patent).  But he did not look for 
>compression delivery patents.


Kevin Kiley

PS: As with the previous message regarding ZLIB memory leaks,
Dr. Mark Adler's verbatim comments are reprinted here on this public 
forum with his full permission.

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