[e2e] a means to an end
David P. Reed
dpreed at reed.com
Tue Dec 2 10:08:35 PST 2008
Objects != information. No need to objectify information anymore than
need to objectify women. :-)
Regarding flooding - the alternatives not so black and white as you make
them out to be.
Search can scale rather dramatically, under the same conditions that
routing can scale: when things don't move.
The difference is that search doesn't require that the pre-condition of
static placement be satisfied... a good search strategy adapts its work
effort to conditions.
Instead of flood first, one could do depth-based search from a landmark
near the last appearance known, if given a network that is relatively
static, where things move slowly.
Algorithms are great things. They can be designed to adapt, while still
doing well in simple cases.
So "flooding" seems just a straw man argument made by those who don't
want to consider adaptive algorithms.
David Andersen wrote:
> Interesting discussion. I sense something fundamental here in the
> needles vs. haystack side of things: one can find hay easily without
> needing to embed location at all, b/c you can flood to find it and
> expect to find it soon. For scalability, though, needles need some
> well-defined rendezvous point.
> That rendezvous point eventually needs to map to a physical
> realization that stores, at minimum, a mapping that tells you where to
> get the data you're interested in. Or could store the data itself.
> This is, of course, assuming that the # of data objects in the
> universe is substantially larger than the # of globally, independently
> routable objects in the universe. Which is probably a reasonable
> assumption for the medium term.
> On Dec 1, 2008, at 11:53 AM, 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
>> eventually, or not, depending on context. It may be that you can
>> retrieve something similar from other, more widely available,
>> 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
>> Van's) embeds a location.
>> In message <49340902.2050400 at reed.com>, "David P. Reed" writes:
>>> 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
>>> 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 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
>>> 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
>>> 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"
>>>>> "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
>>>>> there must be a "place" where it "is" is an idea whose time should
>>>>> and the purveyors of that idea as a holy writ (the OSI layering)
>>>>> to play golf.
>>>> Hi Dave:
>>>> Much as I'd like to believe this particular theory (as it is nice,
>>>> 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
>>>> 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
>>>> 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.
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