[bt-spec] addresses and identification

[Mark Little <mark_little@hp.com>]

I'm going to try to address the differences between the two schemes being
proposed for URIs and their usage (and no pun intended).

HP would have Identifier+endpoint as a URI as the way in which to uniquely
identify and contact some entity (how the entity is found is down to how the
information within the URI is interpreted. Multiple additional (and
optional) URIs are also used to locate the "same" entity.

Choreology would have Identifier to identify (a URI) and address as a
separate piece of data.

Now it would appear at first sight like the same amount of information is
being used, but just represented in a different manner. For example (and
let's forget about the format of the address for now as it shouldn't have an
affect on the principle point in this discussion):

HP scheme) http://myaddress.com?1234 http://myotheraddress.com?1234

Choreology scheme) 1234 http://myaddress.com http://myotheraddress.com

However, there is a subtle difference between the two forms which I think
you have been overlooking and which we obviously haven't described well
enough: your scheme assumes that the entity is identified in the same way at
all addresses - this need not be the case.

Take the example of someone (Fred) who can be contacted in multiple ways: 2
phone numbers and 1 mailing address. This individual has a wife and two
mistresses and for reasons known only to him, he has given a different name
for himself to each. So:

his wife knows him as: phone://123456?Fred

mistress one as: phone://09785?John

and mistress two as: snailmail://pobox75?William

All the necessary information is present in each identity to uniquely
contact the individual if we use the HP proposal. In the Choreology scheme
this simply wouldn't be possible unless we decide to have a matrix of
identifiers and their associated addresses - starts to look extremely
complicated. (If you've ever tried to get mail addresses from yahoo,
freeserve, aol etc. you'll know that it can be an iterative process to get
an address you want from one and then you find it's already taken at some
other site - so you end up having different identities and contact point
information even though people who know about all of your addresses still
know they refer to you.)

The alternative is that we agree on some compound format for a URI (address
and location) and work purely in terms of these. Then if the same name is
used at different locations, or different names are used at different
locations, it just falls out of the mix naturally.

Mark.

----------------------------------------------
Dr. Mark Little, Distinguished Engineer,
Transactions Architect, HP Arjuna Labs
Email: mark_little@hp.com
Phone: +44 191 2606216
Fax  : +44 191 2606250