[e2e] a means to an end

Craig Partridge craig at aland.bbn.com
Mon Dec 1 09:32:07 PST 2008

Hi Dave:

I asked Van this explicitly when I interviewed him for ACM Queue in late
October and the answer is that there's an rendezvous point embedded in the
name.  Interview should pop out on-line early next year and you can see if
you agree with my interpretation of what he said.

Re: location -- "location" in my notes means well defined place in the
network -- has nothing to do with physical geography (who cares where
on earth a networked place is?).



In message <49341D2F.50804 at reed.com>, "David P. Reed" writes:

>I've studied Van's and there is no "location" embedded in his system.  
>Unless of course you redefine the word location to mean something quite 
>different than "geographic place".
>Craig Partridge wrote:
>> Hi Dave:
>> So fine, call it datum or message -- the point is that some things that
>> are desired have a single current instance.  That instance may get replicate
>> eventually, or not, depending on context.  It may be that you can
>> retrieve something similar from other, more widely available,
>> sources/instances/etc.
>> But you haven't responded to the point I made which is that when you
>> want something that is rare, what I've discovered is all systems to
>> date embed location.  If I'm understanding your note, you think I'm
>> saying there's a reference copy/instance that we all must go back to
>> ala the Grail (nope, that's not what I'm saying) or that I'm otherwise
>> intentionally making things rare.  Instead I'm saying, when something is
>> rare (1 instance/instantiation/whatever in the world -- and, by the way,
>> I care about such cases as I used to be a medievalist and occasionally
>> was probably the first person to see a document since it was written 700
>> years ago), I've found that every information retrieval system (including
>> Van's) embeds a location.
>> Thanks!
>> Craig
>> In message <49340902.2050400 at reed.com>, "David P. Reed" writes:
>>> Interesting.
>>> Your presumption that information is a matter of copies, and that "sole 
>>> copy" is a well-defined term, suggests a fundamental difference in our 
>>> understanding of the word "information".
>>> Had you used the word "datum" or "message" (two human constructed 
>>> concepts), I might agree.  But "information" is not a synonym for either 
>>> term.  Both are *representations* or *instantiations* of information.
>>> A piece of paper with a number printed on it may be the "sole instance" 
>>> of a printed piece of paper with that particular representation of 
>>> information.   But if that number represents (say) "the total net value 
>>> of my bank account on Dec. 1 2008", it is not at all the only "copy" of 
>>> information.
>>> Information typically exists independent of form or representation.   It 
>>> is a constructed, calculated, computed thing.  It doesn't exist 
>>> independently, nor does it exist in sole form.
>>> Yes, I could agree with you that if information were forced to exist in 
>>> "single copy" form, it would require some complex and amazing procedure 
>>> to copy that piece of information into another place.  But, once copied, 
>>> it would be smeared across half the universe.  (or alternatively you 
>>> could decide, since "place" is really not a very easy-to-define term, 
>>> that the information is still in one place, but the universe has now 
>>> collapsed significantly, because all the places "containing" (whatever 
>>> that means) the information would be "the same place").
>>> But independent of that: why is any information system designed to have 
>>> data in a "sole copy"?   Van asks this question, and he is wise to ask 
>>> this question.  Most computer systems work by having vast numbers of 
>>> copies of data. We constantly see most information representations used 
>>> in computation in the form of cached data.
>>> It seems to me that it is a pure fetish, perhaps conditioned by 
>>> training, to posit that most information is represented by single 
>>> copies.  That way lies "brittle" failure-prone engineering.
>>> Let a thousand representations bloom.  Many of them will be copies of a 
>>> datum.  Others will be computable recovery algorithms - some of which 
>>> invent an abstraction called "location".   But even that abstraction 
>>> called location is not a "place" in the sense of a 4 dimensional spatial 
>>> metric based coordinate system.   I address a piece of paper by its 
>>> title, not its current location in the file folder on someone's desk.
>>> Craig Partridge wrote:
>>>>> Our dear friend, Van Jacobsen, has decided that layering "where" under 
>>>>> "what" with regard to data is neither necessary, nor a good idea.
>>>>> I agree: confusing the container with the information it happens to hold 
>>>>> is a layer violation.  Information is not bound to place, nor is there a 
>>>>> primary instance.  Information is place-free, and perhaps the idea that 
>>>>> there must be a "place" where it "is" is an idea whose time should pass, 
>>>>> and the purveyors of that idea as a holy writ (the OSI layering) retired 
>>>>> to play golf.
>>>> Hi Dave:
>>>> Much as I'd like to believe this particular theory (as it is nice, clean
>>>> and pretty), practical considerations suggest we're not there.
>>>> I've talked with some of the folks working on information and seeking
>>>> to make information place-free, and the answer, so far, that I've gotten
>>>> is that you get part-way there.  If the information is popular or
>>>> "nearby" then there are mechanisms that can be viewed as place-free (and
>>>> a good thing -- it means that the more popular a piece of information is,
>>>> the easier to get easily and perhaps from somewhere locally).
>>>> But if you ask about retrieving an uncommon piece of information then
>>>> you discover "location" crawls out from under the covers.  That is,
>>>> if you ask the question "where do I find the sole copy of item X", you
>>>> learn that somewhere hidden in the name of X is a location -- perhaps
>>>> of X or perhaps of a rendezvous server that knows where X is -- but
>>>> there's the location of something buried in there.
>>>> Thanks!
>>>> Craig

More information about the end2end-interest mailing list