RE: [xml-dev] xml:href, xml:rel and xml:type

["Len Bullard" <Len.Bullard@ses-i.com>]

As dull and tedious and odious as it would be, I suppose someone should
tell without names what the history of SGML/XML is and why it is applied
in all kinds of data storage and retrieval systems including hypermedia
and hypertext.

The point in short is, XML isn't a format.   It is a system,
specifically, a syntax system for creating formats used by other
systems, notably, hypertext systems (depending on what you spec,
hypertext is a superset of hypermedia; one can argue otherwise, but only
by stepping out a level of system abstraction).   It is these layers of
system abstractions and systems applied to create
functionally-delineated systems (Guns A Go Go) that confuse people who
haven't been through the whole nine yards of history in warping the web.

XML is a part/system of a hypermedia system.   HTML is part/system of a
hypertext system.  How many systems does it take to turn on a lightbulb?

BTW: the early SGML hypermedia systems were more like you are looking
for.  This is a case where we went from complex advanced systems to
simple basic systems in order to achieve scale.   A question of some
interest is to explore what aspects of scale were, in the minds of the
designers, unachievable with SGML prior to XML.   But the idea that SGML
cannot be used in large scale open hypermedia systems is false.   That
it hasn't been is historically true.   Separation of concerns is at the
top of the list why that is historically true and true when attempting
to implement all of the systems required by multiple people in multiple
locations working on different projects that share some requirements.
There are also some ego bruising politics but like most politics, they
now only matter to those who were first person shooters at the rodeo.

Forget the abstract notion of relationships for a moment.  How many ways
are there to link into and out of a 

file/entity/blob/database/map/image/video/real-time-3D/bag-o-bits?

Once you tackle that problem, you have an understanding where things
stood in circa 1988/89 when we began to discuss time as well.

len

-----Original Message-----
From: Rushforth, Peter [mailto:Peter.Rushforth@NRCan-RNCan.gc.ca] 
Sent: Monday, April 16, 2012 2:22 PM
To: liam@w3.org
Cc: xml-dev@lists.xml.org
Subject: RE: [xml-dev] xml:href, xml:rel and xml:type

Hi Liam,

> The goal was to put SGML on the Web. It was difficult to use 
> SGML on the Web at the time. 

XML on the web is difficult, so I would say XML has fallen short of this
goal in at least one respect:  it's not a hypermedia format.  You don't
have to get 100%
on the exam to be a success, so I'm not saying XML is a failure, but
there's room for improvement.  

> The goal was not to replace HTML.
Which has a different goal than XML, obviously.

> 
> Peter - the short answer is that painting the railway engine 
> green won't make more people travel by train. There's no 
> single magic bullet. 

Fair enough.  Making XML into a hypermedia format involves more than
links anyway.
But, if the base format does not have links, then only formats which
derive from 
a format in the (derivation) tree which defines links will have links.
So the only formats
to have links in XML are those which use xlink.  Does XForms use xlink?
I'm not
saying it should, but to leverage software libraries which do implement
links,
it might want to.

> There are barriers that could be lowered 
> a little, but there also has to be incentive, you have to 
> offer things that people already know they want.

I'm interpreting the paucity of support for xlink in XML clients to mean
that
there is an unfulfilled need at the XML level.  That's just my
interpretation
of course. 

> 
> For trains, it's a perception of a frequent and fast service 
> with no need to book a seat.
> 
> For computer formats it's making something easier than what 
> people currently do - not equally easy, but easier. 

Good point.  

Regarding xml:href, xml:rel and xml:type :

0) XML is not a hypermedia format - it needs links at a minimum to get
up to that bar -
1) The XML namespace and its prefix are hardwired onto xml, and so offer
an appealing point of entry for the sake of simplicity
2) Information models which don't specifically exclude such attributes
appear to allow them
3) They don't prevent use of any other XML construct, as far as I can
tell, including xlink.
4) "xml:type" has no equivalent in xlink - no typed links.  I think same
for "xml:hreflang".  These aspects support the "Web" (REST) (I think).

Obvious continuing need to crowd-source the benefits and potential
barriers. :-)


> > > If "mastery of the Web" _had_ been a goal, XML would have 
> been very 
> > > different, as Jeni Tennyson pointed out in her keynote at 
> XML Prague 
> > > this year.
> 
> I apologise to Jeni for the typo in "Tennison".
> 
> > Yes, I saw the video, but I forget this specific point.  
> Did she say 
> > how it would have been different?
> 
>   ``What might have been is an abstraction
>     Remaining a perpetual possibility
>     Only in a world of speculation.
>     What might have been and what has been
>     Point to one end, which is always present.''

:-)

Cheers,
Peter

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