You can also get the pdf file of the topic maps standard at:
http://www.y12.doe.gov/sgml/sc34/document/0129.pdf which is bound to open
with Netscape and that has all the information about roles and associations
but probably in less readable form.
Gil
-----Original Message-----
From: Eric Armstrong [mailto:eric.armstrong@eng.sun.com]
Sent: vendredi, 3. novembre 2000 01:56
To: unrev-II@egroups.com
Subject: Re: [unrev-II] Jack's Use Case: Context-sensitive representation
Apparently this site can only be viewed in Explorer?
It sure isn't displaying well in Netscape 4.7.
"Regev, Gil" wrote:
>
> Eric,
>
> check out the Topic Maps trail at 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
>
http://www.topicmaps.com/machinery/intermediary.asp?file=../content/trails/r
esolved\step1.xml they
> start discussing roles of associations at step 7. You can find the ISO
> standard at http://www.y12.doe.gov/sgml/sc34/document/0129.pdf
>
> Gil
>
>
> -----Original Message-----
> From: Eric Armstrong [mailto:eric.armstrong@eng.sun.com]
> Sent: jeudi, 2. novembre 2000 00:54
> To: unrev-II@egroups.com
> Subject: Re: [unrev-II] Jack's Use Case: Context-sensitive
> representation
>
> 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
> user.
>
> 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
> came.
>
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