<XML:SCRIPT>

Peter Murray-Rust peter at ursus.demon.co.uk
Thu Jul 9 01:52:15 BST 1998


Eliot,
	There seems to be either some magic or some implied semantics in your
processing. The following questions are asked from (my) ignorance:

At 14:16 08/07/98 -0500, W. Eliot Kimber wrote:

[...]
>
><?XML version="1.0"?>
><!DOCTYPE MyDoc [
>  <!NOTATION JavaScript PUBLIC "+//IDN netscape.com//NOTATION Java
>Script//EN" >
>...
>]>
>...
>
>This serves to connect the local name "JavaScript" to the formal
>specification that can presumably be found at the other end of the public
>identifier for the notation. By definition, the external ID for a notation
>is supposed to get you the human-readable definition of the notation. You

What automatic mechanism is available for finding a document at the end of:
	"+//IDN netscape.com//NOTATION JavaScript//EN"
Is there a set of maintained FPI servers like DNS? Because if not, an FPI
isn't very useful to me.

[...]

>When this document is processed, a processor can see that there is a
>notation attribute (that is an, attribute whose data type is "NOTATION"; by
>convention we normally use the attribute name "notation" as well, but
>that's not required).  It knows by the rules of XML/SGML that the named
>notation governs the interpretation of the element.  It looks up the
>notation information and sees the external ID for JavaScript (it must key
>off the external ID because the notation name JavaScript is a local name
>and could be anything--you can't depend on authors using the string
>"JavaScript", even though most will).  

Agreed. Is there a generally agreed way of writing portable code to do this? 

>
>It sees that there is a dll function or plug in or module or COM object or
>JavaBean associated with that name and passes the element to it (presumably

How does it do this (algorithmically)? This is the key question to which I
have been trying to get an answer - (although I want Java classes rather
than *.COM or *.dll which are platform-dependent). 

>a pointer to the in-memory representation of the element, or possibly the
>string representation of the element, depending on the nature of the
>processor). The notation processor then does whatever it does and comes
>back, returning whatever the interface between the main processor and the
>notation processor requires or allows.
>
>This is essentially what you do to process objects with different MIME
>types. The only difference is that notation types are not pre-defined or
>necessarily registered anywhere because notations are a more general
>facility than MIME types. You can associate notations with individual

The advantage of MIME types is that there is a well-defined mechanism in
current software for associating MIME types with software. AFAIK there is
no generally agreed and implemented mechanism for associating FPIs with
software. If there is, I'd love to know. It must, of course, be:
	- free
	- documented
	- easily available
	- platform independent.

Perhaps a related question is "which of the current crop of XML tools
associates NOTATION and FPI with software?"

	P.


Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary
http://www.venus.co.uk/vhg

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