Hi Kurt:
Good response. You've provided a useful Programming Language feature definition
correlation with XML features.
If going strictly from standards, a Markup Language is a language, but it is not a
"Programming" language? Standard XML now, clearly, is not a programming language. In
the future, as more functionality becomes standard, perhaps it will be.
Roy
-----Original Message-----
From: Kurt Cagle [mailto:[EMAIL PROTECTED]]
Sent: Saturday, January 08, 2000 2:09 PM
To: Roy Roebuck
Subject: Re: XML as Programming Language??? Surely Not!
Roy,
I would agree with you that XML, if taken solely to mean the W3C XML
Specification of 1998, is not a programming language. However, when you
start adding in all of the associated XML technologies, the distinction
becomes much, much fuzzier. Consider the definitions of a program
1) A program is a transformative entity, converting data from one
representation to another. This describes XSL-T
2) A programming language has the ability to perform logically analysis
based upon parameterized values. This also describes XSL-T.
3) A programming language has the ability to create conditional looping
structures. XSL-T again.
4) A language typically can link in with other language components. This
describes X-Link.
5) A language allows for the creation of local variables of information. XML
entities nicely fit that bill.
6) A language has one or more ways of addressing information contained
within its space. XPath.
7) A language usually has external links to both input and output streams.
This is the essence of XML/XSL.
Let's take a more stringent look at XML as OOPL.
1) Any OOPL provides the triad of Encapsulation, Inheritance and
Polymorphism. Once XML Schema gets ratified, all three of these aspects
will be in there (look at Archetypes, for example).
2) Most OOPLs also have the notion of data-typing, both at the primitive and
at the aggregate level. XML Schema again.
3) OOPLs contain abilities to call methods, raise events, and access
properties.
This is the one that needs to be examined most closely, because I think this
is where the "This is not a programming language usually comes down to".
The current implementation of XSL-T gives you the ability to "call" XSL
templates with parameterization. As these calls are usually done on
specific nodes of the XML structure, this is roughly analogous to the method
call stack. Events on the other hand are a function of the specific XML
server implementation, although most have some form of eventing.
Can XML exist is an independent language -- no, of course not .. in
uncompiled form. Can C++ exist as an independent language ... well, no, not
in an uncompiled form.
So tell me, how is XML not a language?
-- Kurt Cagle
----- Original Message -----
From: "Roy Roebuck" <[EMAIL PROTECTED]>
To: "XML EDI Listserver (E-mail)" <[EMAIL PROTECTED]>
Sent: Saturday, January 08, 2000 9:33 AM
Subject: XML as Programming Language??? Surely Not!
> The characterization of XML as a programming language is interesting, but
seems false. One could program the behaviors of the named structural
entities tagged using XML compliant text markup, by applying some
behavior-descriptive language (e.g., script [ECMAScript, VBScript,
JavaScript, etc.], procedural [C, Perl], object-oriented [C++, Java], or
hybrids [Python, PHP]), but XML itself doesn't provide any more than tree,
associative, change, or streaming structure. XML provides named entities
and structure, programming provides behavior. Even when UML applies XML to
exchange system models/knowledge with other UML-enabled tools/repositories,
the behavioral aspects of the models/knowledge are defined using the UML
tools, not XML.
>
>
> Ref. earlier threads:
>
> "....I agree mostly with Michael's point. I'll restate and expand: xml is
a programming language with a facility to define and structure data....."
>
> "...I disagree with you when you classify XML as a programming language.
It is at a higher level than that, in the way it frees you to model the
entities, the processes and even the language with which express your
processes...."
>
> "....How can XML as a programming language ever replaces a set of
standards or format like EDI?..."
>
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