Plea for help: The detriment of using Microsoft products

[Jeffry Smith]

On Mon, 15 May 2000, Derek Martin wrote:
>   XML
> 	Admittedly, I don't know very much about XML.  A lot of the OSS
> 	office suites seem to be using it a lot for their data format.
> 	I gather it's a lot like HTML but more extensible.
> 
Actually, it would be more to say that HTML is a select subset of XML 
(eXtensible Markup Language), which is itself a subset of SGML
(Standard Generalized Markup Language).  SGML was developed as a Gov't 
standard for marking up documents (this is a header, this is a
chapter, this is a graphic, etc), that became an ISO standard.  It
specifically does NOT cover display, that is done via a viewer that
takes the SGML / XML, applies the Document Type Descriptor (a
meta-document that explains what the tags in the main document are),
then applies transform rules for your display / item to put it in the
correct format, before displaying.   This is a long-winded way of
saying that SGML was designed to separate:
1.  The body of information
2.  The structure of that info
3.  The presentation of that info.

By doing this, transforms become an easy "apply this new set of rules" to the 
document.  It allows the same document to:
1.  Be displayed on a computer screen, 1600x1200
2.  be displayed in a Heads-Up Display
3.  be printed.

All while looking "correct" for that display.  It also allows a system to
transform the document from one automated system to another, because the 
structure info includes more than just "text" (example:  if a tag is
<us-dollars>, than to transform to <uk-pounds> for display in UK, you
could write a program to take the <us-dollors>, multiply by
<us-uk-conversion-rate>, replace with <uk-pounds>.  Note, though, that
the transform does not take place via XML.  XML is a markup
language, XSL (Extensible Scripting Languguage) is a programming
language designed to manipulate XML, and XML can be manipulated by
other programming languages (perl::XML, Java XML parsers, etc).  

Very "Unixy" in design & feel (lots of small tools doing one thing
only, instead of one big thing).  It's not the Silver Bullet that some
make it out to be (every new thing in SW is a silver bullet, yes?),
but, because, if you have the DTDs, you know the structure, and the
clean separation of structure, info, presentation, and manipulation,
once you have a tool that reads DTDs and can apply transform rules, to
manipulate another document written to another DTD, you just plug in
the new DTD.

jeff
------------------------------------------------------------------------
Jeffry Smith      Technical Sales Consultant     Mission Critical Linux
smith at missioncriticallinux.com phone:978.446.9166,x271 fax:978.446.9470
------------------------------------------------------------------------
Thought for today:  There's no sense in being precise when you don't even know what you're talking
about.
		-- John von Neumann


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