[e2e] a means to an end

David P. Reed dpreed at reed.com
Mon Dec 1 09:48:23 PST 2008

It may be that I just can't see the "rendezvous place" in Van's work.  
Nonetheless, I will claim it isn't essential.

Can you define "well defined place in the network", please?  (in 
particular, the words "defined" and "place" need definition here.)

"Nothing to do with physical geography" is an interesting constraint on 
your definition.

I would claim that the word "place" in your definition is nothing more 
than a synonym for "function that is effectively computable by a 
realized physical computational device".   In other words, a computed 
mapping from "the state of the entire system" to an element of an 
abstract set of values.   For example, an algorithmically computed 
mapping from the state of the entire system to a member of a set of 
items that have 2^32 possible states.

The algorithm here might involve many things, but is very rarely focused 
on what we consider physical location.  As you admit when you say 
"nothing to do with physical geography".

So define "well defined place in the network" as YOU define it.

Craig Partridge wrote:
> 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?).
> Thanks!
> Craig
> 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
>  >d
>>> 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

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