Altova Mailing List Archives

Re: Why the Infoset?

From: John Cowan <jcowan@-------------.--->
To: Sean McGrath <sean@--------.--->
Date: 8/3/2000 11:08:00 AM
Sean McGrath wrote:

> The W3C infoset work seems to be to bless two levels
> of abstraction:
>         a) XML entities are a stream of bytes
>        b) XML entities consist of elements,attributes,data ...
>        (all the stuff in the Infoset doc)

Actually, there are (a1) the byte level and (a2) the character level.
Both are important.

> (X) This is the space where what SGML called
> "markup sensitive" apps. live. Apps that care about the
> difference between "Hello world" and "&greeting;".
> Apps that care about default attribute values etc. etc.
> (Y) This is the space where high fidelity roundtripping apps
> live. Apps that care about the difference between:
>         <name first = "Sean" last = "Mc Grath"/>
> and:
>         <name
>                 last = 'Mc Grath'
>                 first = 'Sean'></name>

I think it's pretty arbitrary of you to call the Y level "high
fidelity", just as it's arbitrary for me to call the b level
"the Infoset".  But we both agree that a line must be drawn somewhere.

> There needs to be N infosets (N > 1) to cover
> the range of application types people build with
> XML.

We used to have that explicitly, with a "minimal infoset", a "maximal
infoset" and every possible infoset in between.  It was a mess to
describe.  Now we have:

	1) one standard infoset
	2) conformance means documentation of what you provide and what you don't
	3) any app can add its own info items and properties
		(right down to the a level if you want)
	4) the "core conformance" infoset is one possible subset


Schlingt dreifach einen Kreis um dies! || John Cowan <jcowan@r...>
Schliesst euer Aug vor heiliger Schau,  ||
Denn er genoss vom Honig-Tau,           ||
Und trank die Milch vom Paradies.            -- Coleridge (tr. Politzer)


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