check out the Topic Maps trail at http://www.topicmaps.com/
<http://www.topicmaps.com/> I believe they have defined roles of
associations the same way as you do in this message. The trail starts at
ils/resolved\step1.xml> they start discussing roles of associations at
step 7. You can find the ISO standard at
From: Eric Armstrong [mailto:email@example.com]
Sent: jeudi, 2. novembre 2000 00:54
Subject: Re: [unrev-II] Jack's Use Case: Context-sensitive
Thanks again for raising this critical question,
Jack. It got the juices flowing, and this morning
the answer arrived, as it always does, like a
tiny bolt of lightning in the quiet of morning.
There is a analagous concept in O-O design: the
concept of a *role*. In that context, the idea
of a role emerges when one realizes that a particular
noun in a system description does not represent a
new object, but rather the name of a variable -- a
particular way of characterizing an existing object.
Thinking in terms of "roles" led me to put your
question together with Doug's magnificent
tour de force: the concept of a adding
*view control* to a link.
In essence, the situation with Sally is that there
are multiple views. "Sally" can be representated as
an object with many views (if she is thought of as
a hierarchy or graph of characteristics) or as an
object with many interfaces (if she is thought of
as a classic O-O object).
The important point is that "referencing" the
object known as "Sally" always takes place in
some *context*, and in that context, one view
or another is appropriate. That "view" of her
characterisitcs constitutes the "role she plays".
[Intentional ambiguity alert: You "play a role"
when you are on stage, in the sense that it is one
view of who you are. You also "play a role" in
any given context, in the sense that you fulfill
some specific set of functions.]
The moral, then, is that any link to any object
in the system must be qualifiable with respect
to it's "role", in the same way that any link
to any part of hierarchy must be qualifiable
with respect to view.
For me, the moral is that any reference to a
globally unique user ID must also be qualifiable
with respect to a "role" or "view" of that
The reason: User IDs are used for attribution.
Every attribution should become a link to
information about that individual.
But the information displayed for that individual
should depend on the context. The "bio" paragraph
I use for technical articles is significantly
different from the one I use for exercise/nutrition
articles. In the same way, the view of "me"
presented by traversing a user ID link should be
different, depending on the context from which it
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