Jon Bosak wrote:
> ...what we seem to be left with is a clear reason to define
> a contextual link mechanism for general Internet use in our first link
> specification document and a possible case to be made for defining an
> independent link mechanism for intranets that we may want to put in a
> first link specification document or may want to defer for a later
> Is that right?
We need independent links for link management in a multihub hypermedia
system where a hub language is any handled type that is hyperlink
capable (multimedia). E.g, an Illustrated Parts Breakdown and the
graphic sequence (called a Figure, but multiple sheets) contain
bi-directional content relationships which are more easily managed
with independent links. We do it now with clinks. Hard to maintain.
IMO&D, independent links are address records; clinks are controls
with local address records. Confusion starts there.
Self-awareness is not a good metaphor. Some contributions form
the object-oriented community would help here (Derek? Gavin?)
HyTime, TEI, FPI, URN, I don't care: ease of management of n-way links
what is needed. What would really help this discussion more than
abstractions on linking would be set of IDLs for an XML handler.
Define the XML handler public services.
For object oriented programmers to build what we
say we want, we have to tell them how much the XML spec
defines the behavior of the system that handles it?
What services do we want from that .dll? What is
the XML handler interface to the framework?
Location resolution is a framework feature. It's a protocol issue.
Protocol implementation is a system implementation. Engineers
know this and so demand that a proposal for a protocol always
be backed up with the code that runs it. Fact of life these days.
o Will XML hyperlinks be designed ad hoc? I have mine, you have yours,
etc. That is the current situation with respect to SGML hypertext
systems. We all have hyperlinks.
o Are we to define minimum interoperability of hyperlink types?
o Are we defining types of hyperlinks
which are extensible semantically (attribute, GI, whatever)
o Are we to develop a set of element types which are
XML hyperlinks? (i hope not but it's the easiest punt)
Given: If XML wants to define hyperlinks, XML has to provide an
implementation of the protocols required to support the
hyperlinks or ensure the hyperlinks fit within the constraints
of existing protocols.
OTH, hyperlinks are not locators. Do we have to design a protocol?
Do we need a stateless or a stateful protocol? Both?
WWW Today: URL with sub-file target parameters (e.g, #targetname, string
du jour) or URL as address type for semantic, e.g, object, img,
thingieDuJour). For comparison, here is a VRML anchor:
eventIn MFNode addChildren #tree operations
eventIn MFNode removeChildren
exposedField MFNode children
exposedField SFString children [ ] #geometry, materials, lights, etc.
exposedField SFString description "" #displayed text
exposedField MFString parameter  #value-pairs, eg, frame targets
exposedField MFString url  #get this, target, move-to-viewpoint
field bboxCenter 0 0 0 #local space origin
field bboxSize -1 -1 -1 #max size local space
We use a similar mechanism in IDE/AS where the link has goodies such as
targetname (file), system handler (who gets this), system arguments
(commands and command parameters (byte offsets, pixel positions,
named objects) all used in the DDE dance).
In some cases, (e.g., graphics) all documents of that content
type are being handled by a single system (e.g., ImageMaster).
Look's like a helper app but not really. It is actually a peer
in the sense that it also handles a hub-capable data type
where a hub-capable type has hyperlinks.
Hub: any notation that is hyperlink capable.
How does XML represent hyperlinking services to the
other notation handlers? Other hubs?
Could we just say, object handlers?
o Is this an XML-definable content relationship?
o Is this a Java or Active-X interface?
Services of objects are defined by the framework.
Are we offering an abstraction of that?
One way to look at this is to ask, for n-way links
what is as the minimal service set available to all
hubs in the system?
o What are the services of the objects of the framework
in which XML handlers operate?
o What are the services of the XML handler?
o What are the requirements of the XML user that must
be implemented in the XML handler services?
Requirement: easier management of linked relations
(e.g, independent links)
Requirement: declare relations among content types
without needing to know the handler type at the
hyperlink or at least, where that is prioritized
and/or negotiated (e.g, location ladders)
Uni-directional links are hard to build and maintain
for some content types. For example,
the relationships between an IPB and the figure
sequence to illustrate it are bi-directional.
We end up coding every link twice in a domain whose
range is bounded by topic, task, part, script, etc.
On a good day, twice the maintenance, twice the
The relationships to the procedures which use the
IPB/graphic are indexed to the key numbers of the
IPB/graphic where the key number names the
relationship by local unique id (number list),
not logical name.
From any content node in this system, there
may be collections of nodes which support this with
topics (description, task-direction, policy, e-mail,
task recording (e.g, collaborative)).
o An XML hyperlink designer might want a way to validate a
referenced content type.
o An XML hyperlink designer might want to say, in this IPB, this
table always has a set of view types (graphic primitives in CGM,
camera positions in VRML, bitmaps in whatever), or in this
procedure, a collection is returned by a query whose parameters
are output conditions of the last procedure
o An XML hyperlink author might want to say, here is a list of
URLs, (priority, aggregate, etc.)
XML has to be able to support all of that because
XML users need all of that. XML has to support
not just the Web, but what the Web is becoming:
a business for authoring to the street in
one straight no-nonsense publishing path.
When books emerged, it was not from academic
struggle or desire. It was when certain merchants found
it necessary to smuggle records in carts of linen
across borders. Then the academics and the merchants
had all the books they could have ever wanted.
dec 25, 1996