Re: [RAM] Ramblings about "locator"

[jnc at mercury.lcs.mit.edu (Noel Chiappa)]

    > From: Brian E Carpenter <brian.e.carpenter at gmail.com>

    > My original RAMble (sorry) ended thus:

    >  Maybe the essential point is that a locator can at least in
    >  principle be mapped to topology and an identifier can't.

My human-name can be mapped to a telephone number. My human-name is not,
however, a telephone number. An "identifier" can certainly be mapped to a
network location with the aid of the appropriate database, just as a DNS
name can be mapped to a network location.

Maybe you're using the wrong word, and instead of "mapped" you really meant
something like 'directly related', or something like that, but the problem
is that that's a somewhat nebulous turn of phrase. Which is why I
previously suggested that nice gold-standard, easily-comprehendable tests
for 'does this name have location information embedded in it' are:

- Do you have to get a new one when you move to a new location?
- Given two location-based names, can you tell, by comparing *just the
	names*, whether they are 'close' to each other?

Maybe someone else can come up with a snappy word/phrase which clearly,
cleanly and concisely embodies that very close relationship...


    > A slightly different way to say it is that a locator is a handle for
    > a route.

No. My street address is not a handle (in any simple sense) for directions to
my house. Yes, with a lot of data (connectivity information), and a certain
amount of computing, it can be turned into directions, but the relationship is
not a simple one.

This was all quite clear a long time ago; see IEN-19, John Shoch,
"Inter-Network Naming, Addressing, and Routing", January 1978, now finally
available at:

    ftp://ftp.isi.edu/in-notes/ien/ien19.txt

Everyone here should be familiar with what it has to say.

	Noel

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