RE: [xml-dev] Parser&DTD....

["Jimmy Cerra" <jc2astro@hotmail.com>]

> I don't know much about a xml parser and what it is doing and how I can
> write a parser for myself

Trust me...  It's not as easy as it sounds (I'm writing one right now).
However, the challenge is both extremely instructional and rewarding, so go
ahead and try if you want to. :-)

Also, you'll need to get two books (at least, they have been very valuable
for me):

1) Goldfarb, C. F., Prescod, P.  (2002). "Charles F. Goldfarb's XML
Handbook" (4th Ed.).  Upper Saddle River, NJ: Prentice Hall PTR.

2) Garshol, L. M.  (2002). "Definitive XML Application Development".  Upper
Saddle River, NJ: Prentice Hall PTR.

> I mean we call it valid in relation to its DTD but when it is invalid.

First, an XML document must be well-formed - in other words it must follow
the grammar of XML precisely.  Every XML processor (parser) is required to
make sure that the document is well-formed; if not then it must return an
error and stop parsing.

Second, an XML document may be valid (aka type-valid) if it conforms to the
DTD - in other words it may follow the spelling and context of the
particular language.  (Note: XML is not a language; it is a way of defining
languages.)  Not every XML processor (parser) is required to check to see if
the document is valid.  Generally, validating processors (parsers) are much
more complicated than non-validating processors.

> what is a Style Sheet,and CSS?

Generally, you want to separate content (words and text) and presentation
(how it looks or presented to the user).  Style Sheets allow you to do this:

First, you write an XML (or HTML) document with only semantic content (or
raw data) marked up by tags describing what that content is (like <author>
or <date> or <paragraph>).

Then, you write a Style Sheet that describes how to format the content.  The
Style Sheet can define the fonts, colors, positions or other "fluff" of the
content.  There can be multiple Style Sheets per document (so it looks like
a newspaper in one instance or a book in another).  CSS is one (popular,
non-XML) language for describing these styles (also know as rules).

Style Sheets can also transform the document from one language (such as
XHTML) to another (such as PDF, LaTeX or plain ASCII) and add content (such
as determining a table of contents by counting the number of headings in the
document).  This type of Style Sheet uses a language called XSLT.  (Note: I
refer to these as XSLT sheets, following Håkon Lie's advice at
http://people.opera.com/howcome/1999/foch.html#footnote1 .)

> Thank You Very Much!

I read somewhere that is considered bad etiquette to thank someone before
that have done anything for you.  However, I often have bad etiquette, so...

You're Welcome. :-)

> Be Successful!

Thank you; you too.

--
Jimmy Cerra
jfcst24@stargate.pitt.edu


============================================
"my mind is slipping away...
                   ...day by glorious day"
Robin Gorkin
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