Schema vs. Vocabulary

Sathyaish

Thingies:

- Report Definition Language (RDL)
- Resource Definition Framework (RDF)
- Web Service Definition Language (WSDL)
- C# Application Markup Language (CSAML)
- Extensible Application Markup Languaeg (XAML)
- Or, HTML itself?

Are these not specific vocabularies? OK, HTML may not have very rigid
rules, and it doesn't care a fuck about case-sensitivity and validity
(for most tags). It only cares about well-formedness. And it existed
before XML. And as said, is an implementation of SGML.

My Pondering Begins
----------------------

SCHEMA
Schemas are a manifestation of rules of occurance and sequence. A
validator can validate an XML artifact by comparing that it conforms to
the rules defined in a schema.

What are vocabularies, then? Aren't they the same?
VOCABULARY
As I understand, a vocabulary is a definition of an XML format to
embody information specific to a discipline or domain.

Questions:

1. How is the definition of the vocabulary made? Using an XML schema?
2. A schema can also describe something more generic than a vocabulary.
So, am I correct in understanding that a rule-definition mechanism for
"any" XML artifact whereas a vocabulary is a specification, expressed
using a schema, only for a narrower set of XML artifacts that pertain
to a peculiar discipline?

Essentially, how do the two relate to each other? That conclusion begs
the question, "what are the things mentioned above (WSDL etc.), then?"


PS:
Just to add another bit, RDL is still proprietory, and not yet an open
standard:
http://www.theopensourcery.com/wordp1/index.php?p=66

http://www.microsoft.com/sql/technol...g/rdlspec.mspx

http://www.codeproject.com/csharp/RdlProject.asp

So, what does that make RDL?

Apr 11 '06 #1

Joseph Kesselman

(Original message was crossposted to an MS newsgroup that I can't post
back to.)
Sathyaish wrote:

Are these not specific vocabularies?
Yes, modulo the fact that HTML is an SGML vocabulary rather than an XML
vocabulary. XHTML, which W3C hopes will eventually replace HTML, *is* an
XML vocabularly

And modulo the fact that "vocabulary" is not an official term in the XML
world.
SCHEMA
Is a language for writing a machine-readable description of XML data
structures. Put those together, either in one schema files or multiple
schema files, and they add up to a vocabulary.
1. How is the definition of the vocabulary made? Using an XML schema?
Plus whatever conventions are imposed by the language's author and the
applications which manipulate it. Schema can only provide a very basic
initial check -- a sort of "high-level parser" -- with semantics being
imposed by the applications, and semantic checks must occur at the
latter level.
2. A schema can also describe something more generic than a vocabulary.
I'm not sure what you mean here.
Essentially, how do the two relate to each other? That conclusion begs
the question, "what are the things mentioned above (WSDL etc.), then?"

Higher-level descriptions of the semantics associated with these
documents (though still below the application level).

--
Joe Kesselman / Beware the fury of a patient man. -- John Dryden

Apr 11 '06 #2

Johannes Koch

Sathyaish wrote:

Thingies:

- Report Definition Language (RDL)
- Resource Definition Framework (RDF)
- Web Service Definition Language (WSDL)
- C# Application Markup Language (CSAML)
- Extensible Application Markup Languaeg (XAML)
- Or, HTML itself?

Are these not specific vocabularies?

RDF is _not_ a vocabulary.

xpost and f'up2 comp.text.xml.
--
Johannes Koch
In te domine speravi; non confundar in aeternum.
(Te Deum, 4th cent.)

Apr 11 '06 #3

Peter Flynn

Sathyaish wrote:

Thingies:

- Report Definition Language (RDL)
- Resource Definition Framework (RDF)
- Web Service Definition Language (WSDL)
- C# Application Markup Language (CSAML)
- Extensible Application Markup Languaeg (XAML)
- Or, HTML itself?

Are these not specific vocabularies? OK, HTML may not have very rigid
rules, and it doesn't care a fuck about case-sensitivity and validity
(for most tags). It only cares about well-formedness.
This is a common misunderstanding. HTML is just as rigid as XHTML,
modulo the differences between SGML and XML. It was explicitly
designed NOT to require case-sensitivity. HTML can be perfectly
validated using any standard SGML validating parser: it's the
*browsers* that don't give a fuck about validity, because it was
decided at an early stage that trying to enforce the rules of
SGML on page authors would make it too difficult.
My Pondering Begins
----------------------

SCHEMA
Schemas are a manifestation of rules of occurance and sequence. A
validator can validate an XML artifact by comparing that it conforms to
the rules defined in a schema.

What are vocabularies, then? Aren't they the same?
VOCABULARY
As I understand, a vocabulary is a definition of an XML format to
embody information specific to a discipline or domain.

Vocabulary is a portmanteau word to avoid having to say "DTD or Schema"
every time. It's also useful when discussing an XML application with
people who don't grok markup.

///Peter
--
XML FAQ: http://xml.silmaril.ie/

Apr 11 '06 #4