xml-dev - Re: Services-based automation (WAS RE: Realistic proposals to the W3C?)

["Thomas B. Passin" <tpassin@home.com>]

Jonathan Borden wrote -

>
> The XML model defines a node labelled directed graph. In
this model, arcs or
> edges have the type "element" "attribute" "CDATA section"
"comment" etc.
>
> The RDF model defines an edge labelled directed graph, for
example arcs may
> be labelled "color", "type.of.cheese" "type.of.sauce"
"topping". This may
> not seem a radical difference but understand that software
which makes
> inferences regarding the properties of a pizza, as
represented in an RDF
> graph, may be totally unconcerned about whether the
"type.of.cheese" is an
> attribute or an element and whether this property is
serialized before or
> after the "type.of.sauce" property.
>

A basic edge-labeled graph defines its structure mainly by
edges, keeping its values or data in the nodes.  The node
model for xml uses nodes to delineate the structure as well
as to hold data.  The edge-labeled model has a cleaner
separation of structure and data.  I happen to like working
with a edge-labeled model better, the DOM uses a node model.

Do the two models really represent anything different? Not
really.  But if connections - a form of structure - are the
most important thing to you, edge-labeled models might seem
more attractive or "natural".  In either case, we are
looking to the labels to give us clues as to the "meaning",
or at least to the "use".  In a csv file, this would be
equivalent to having a first row with the column headers.

What do those labels really "mean"?  The labels can't tell
us that by themselves.  They are only precise in a
well-defined domain where there are interfaces or schemas or
some other kind of agreement about how to ***use*** them.
That's Len's  "services".  In that domain, we can know to
look for label "ABC" and we can predict how to use it to get
the results we want.

We can trade precision for a wider range of use by
developing ontologies.  An ontology says what terms are
related to what other ones, at least in an
more-general/less-general sense.  This gives us a more compl
ex, structured set of labels.    But we're still in the same
area of "services".

Cheers,

Tom Passin