Which
is why the Microsoft solution of attaching event handlers via the style sheet
and the namespace works so well. It completes the declaration of the
control type by the event it receives and declares the handler (function) to
fire on receiving the event. In other words, it recognizes that:
1. Link rendering is style rendering in
terms of the objects/conrols the container renders. Any rendered object
that receives events is by definition, a control. An association, on the
other hand, such as “an author is a person” is just an
assertion. It need not be rendered; it just has to be stored.
2. Associating a semantic to an event
received is a late binding processs
Hypertext pioneers recognized long before
HTML that links receiving events are post-rendering controls. This
is the issue that has been bedeviling URI/URLs since they were first
adopted. It doesn’t break anything but it confuses some and makes
it necessary to either attach semantics by a late-bound processing approach or
to fix them in a specification, and of course, ‘slightly different
meanings’ foul up interoperability.
BTW: Linkbases don’t take off
per se because it is easier to do that in a database. Declaring one in
XML is no challenge at all. We’ve been doing from/to links in
VRML ROUTEs and now X3D ROUTEs from day one. Of course, those
standards have an accompanying object model in the standard that ensures differences
of meaning for these don’t occur. They aren’t renderable
controls; they route real time event types.
The semantic problem is an object model
problem. In fact, the linking problems go away if one approaches them
from an object model. That is old news everywhere.
len
From: Nicholas.Ardlie@g...
[mailto:Nicholas.Ardlie@g...]
That’s
right. The process is the harder problem and can’t (shouldn’t?) be
addressed by a linking spec alone.
I’m not
sure how I feel about whether XLink associations are over-specified or
incompletely specified.
Maybe the mix
is about right, but from the ‘Camp 2’ point of view the links, in
any form, end up a black box. (which comes back to process I guess).
Eric’s
comment re: XTM seemed about right to me when he wrote:-
<quote>
Using XLink to
simulate extended links with a bunch of simple links looks to me like saying:
"OK; we'll take the syntax so that we can say we are compliant but we'll
attach a slightly different meaning".
If I am right,
XTM can hardly pretend to be using XLink :) ...
OTH, if I am
wrong, the XLink recommendation should better have defined simple links only
and explained how extended links can be built from simple links.
</quote>
But it’s
hard to think of how to use xlink associations without attaching that
“slightly different meaning”.
Nick.
-----Original Message-----
From: Len Bullard
[mailto:cbullard@h...]
Sent: Monday, 25 September 2006
7:57 PM
To: Ardlie Nicholas;
xml-dev@l...
Subject: RE: Xlink Isn't
Dead
Yes it
does. Are you saying that associating semantics with the XLink
markup are:
O incompletely
associated/specified (not enough data)?
O over
specified (too much data that you have to ignore)?
O not
precise enough about the semantic/process associated (the problem is not the
markup specification but the process specification)?
You are
right that the whole point of indirect association is to specify a
process. Typically when a markup language becomes controversial, it is
not because of the markup (trivial to model that) but because of the
specification for the object that consumes it. That is one reason for
perma threads in XML: debating syntax and data declaration instead of object
methods where the real problems of specification are harder and Not XML anyway.
len
From: Nicholas.Ardlie@g...
[mailto:Nicholas.Ardlie@g...]
GML (Geography Markup Language) also relies on XLink for semantic
association and represents a growing community, riding a gradual uptake of OGC
WFS services.
With metadata standards rapidly maturing in this domain, the GML
community is coming to a point where enterprise support for GML will require
custom XLink models/processors.
Previous experiences with XLink have left me thinking that the
effort/reward ratio is far too low.
I’m interested by the direction of this thread though.
Nick Ardlie
http://www.paleboundary.com/
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