tclxml-users

Re: [Tclxml-users] How to generate an XML document using TCL

[Philip E. <pe...@li...>]

Cameron Laird wrote:
> 	> 	The internal format has nice things like this:
> 	> 
> 	> 	(line has been wrapped)
> 	> 
> 	> 	<int_4s compression='9' format='base64' name='my_data'
> 	> 	        comment='this is my data'> ... </int_4s>
> 	> 
> 	> 	So, I guess XML is to prevent us from writing non-portable
> 	> 	but more readable formats.  But I, for one, think maybe
> 	> 	it's got a bit out of hand.
> 	> 			.
> 	> 			.
> 	> 			.
> 	> I, for a second, sure can't figure out some
> 	> of the marketing perpetrated on XML's behalf.
> 	> 
> 	> Back to technical matters:  Phil, I don't
> 	> understand of what the above is an example.
> 	> Why can't it be XML?
> 
> 	It is an example of a format that anybody involved in processing
> 	numerical data can intuitively understand.  The myth about XML is
> 	that it is immediately interpretable by some magical interpreter,
> 	and no magical interpreter will interpret the above example.
> 
> 	QOTW?
> 			.
> 			.
> 			.
> Sure.
> 
> The fragment above:  it *can* be well-formed XML, right?
> I still don't get your claim that your group invented a
> syntax which is not XML.  I understand that to mean there's
> some syntax which violates XML, but which your group finds
> better-than-XML.  What's an example of that?

Because there is no DTD.  It is XML-like, but XML is just
HTML-like, which is just like something else, etc.  I guess
it is nice to latch on to something and to say it can be
all things to all people, but other than Tcl, I have yet to
see any such thing.  The XML people here screamed bloody
murder about the "internal lightweight format" because
their visual interpreter could not color syntaxify it.

[Tclxml-users] Re: [tclxml] How to generate an XML document using TCL

[<Ste...@zv...>]

Please use the SourceForge mailing list in future:
tcl...@li...

"Rajapurohit, Sunil" wrote:
> I need to generate an XML document using a tcl script, how do i
> go about generating the same ?

When creating XML, I generally use TclDOM.  Create a DOM tree in memory,
and then use 'dom::DOMImplementation serialize $doc' to generate the
XML.  The TclDOM package will make sure that the generated XML is 
well-formed.

Alternatively, XML is just text so there's no reason why you can't
just create the string directly.  Eg:

	puts "<document>$content</document>"

The problem with this is that (a) you have to worrying about the
XML syntax nitty-gritty and (b) the content variable may contain
special characters which you have to deal with.

There are also some generation packages available, like the 'html' 
package in tcllib (this will be added to TclXML RSN, when my 
workload permits).

Hope that helps,
Steve Ball

-- 
Steve Ball            |   XSLT Standard Library   | Training & Seminars
Zveno Pty Ltd         |     Web Tcl Complete      |   XML XSL Schemas
http://www.zveno.com/ |      TclXML TclDOM        | Tcl, Web Development
Ste...@zv...  +---------------------------+---------------------
Ph. +61 2 6242 4099   |   Mobile (0413) 594 462   | Fax +61 2 6242 4099

Re: [Tclxml-users] How to generate an XML document using TCL

[ski <sk...@eD...>]

> > I need to generate an XML document using a tcl script, how do i
> > go about generating the same ?

as i read Sunil's post [and Steve's answer] i wondered out loud:
"why XML?" Sunil talks of inventory data, can i assume a RDBMS
holds this information?

Sunil suggests [reading between the lines] the end result is to
view this inventory data with a browser. so again, "why XML?"

i have yet to write one line of XML. i use PHP to extract the
proper data from any RDBMS and dispaly it in a browser. there
is no 'middle' step. there is only [almost] real time access
to the REAL data in the database. 

how does tcl and XML help in this scenario?

-ski

p.s. i am a huge fan of tcl... and do use it often in my PHP
	solutions. i just do not see the value of XML here.

Re: [Tclxml-users] How to generate an XML document using TCL

[Philip E. <pe...@li...>]

Without defending XML itself, it is trivially easy to convert XML
to HTML ;^)

That said, I would like to tell a little story.

On our project, we intended to adopt XML as our lightweight
data format, because it is supposed to be human readable.

Unfortunately, our imagined idea of what XML looks like was
naive; XML is not very readable!!

We wound up adopting a special "internal" lightweight format
that looks like we wished XML looked, and everybody who sees
it can read it almost from the get-go.

We also wrote conversion libraries that convert our internal
format to XML, but it comes out so ugly that nobody ever does
it.

The internal format has nice things like this:

(line has been wrapped)

<int_4s compression='9' format='base64' name='my_data'
        comment='this is my data'> ... </int_4s>

So, I guess XML is to prevent us from writing non-portable
but more readable formats.  But I, for one, think maybe
it's got a bit out of hand.

ski wrote:
> 
> Sunil suggests [reading between the lines] the end result is to
> view this inventory data with a browser. so again, "why XML?"

Re: [Tclxml-users] How to generate an XML document using TCL

[Cameron L. <cl...@st...>]

	From tcl...@li...  Thu Oct 25 19:45:53 2001
	From: Philip Ehrens <pe...@li...>
			.
			.
			.
	The internal format has nice things like this:

	(line has been wrapped)

	<int_4s compression='9' format='base64' name='my_data'
	        comment='this is my data'> ... </int_4s>

	So, I guess XML is to prevent us from writing non-portable
	but more readable formats.  But I, for one, think maybe
	it's got a bit out of hand.
			.
			.
			.
I, for a second, sure can't figure out some
of the marketing perpetrated on XML's behalf.

Back to technical matters:  Phil, I don't
understand of what the above is an example.
Why can't it be XML?

Re: [Tclxml-users] How to generate an XML document using TCL

[Steve C. <ste...@mq...>]

On Fri, 26 Oct 2001 10:33, Philip Ehrens wrote:
> Without defending XML itself, it is trivially easy to convert XML
> to HTML ;^)
>
> That said, I would like to tell a little story.
>
> On our project, we intended to adopt XML as our lightweight
> data format, because it is supposed to be human readable.
>
> Unfortunately, our imagined idea of what XML looks like was
> naive; XML is not very readable!!

Human readability isn't really one of XML's properties -- more like 
'potential human decodeability' in that it's possible to use XML in such a 
way that the meaning of the structure is transparent. Of course it's also 
possible to use it to make data formats just as opaque as MSWord's binary 
format. 

One of my main motivations for using XML as a serialisation format is that it 
removes the need to invent a new format and write a parser for it.  I'm bad 
at inventing new formats and when I've done it I've always found a little 
later that I need to extend it in some way that I didn't forsee. XML makes it 
much more likely that I'll be able to do that.  It also means that I don't 
need to write the parser (of course this argument doesn't hold if you're 
Steve Ball :-)

Steve

Re: [Tclxml-users] How to generate an XML document using TCL

[Peter F. <pet...@zv...>]

Steve Cassidy wrote:
> 
> 
> Human readability isn't really one of XML's properties -- more like
> 'potential human decodeability' in that it's possible to use XML in such a
> way that the meaning of the structure is transparent.

very true.

> Of course it's also
> possible to use it to make data formats just as opaque as MSWord's binary
> format.

sorry i have to disagree. I never seen xml from any source that was
anywhere near obscure as MSWord's proprietary binary format .. 
Having said that, its true that anyone can make XML content more obscure
than it needs to be by ignorance or lack of effort ...

This leads me to some other benefits of XML - in an emergency I can
_edit_ any arbitrary pieces of xml with just about any simple, ascii
capable editor (i.e just about everything) on any platform without
having to spend a cent.  I doubt that you can compare MSW binary fmts
and XML on any level. <PhilosophicalMode> For lots of reasons MSW
document formats will never be ubiquitous, but XML has the chance to be.
I think thats the key to improving our lot - ubiquitous technology
</PhilosophicalMode>. 

> 
> One of my main motivations for using XML as a serialisation format is that it
> removes the need to invent a new format and write a parser for it.  I'm bad
> at inventing new formats and when I've done it I've always found a little
> later that I need to extend it in some way that I didn't forsee. XML makes it
> much more likely that I'll be able to do that.  

a key feature - the promise of a ubiquitous array of standards based,
extensible, portable tools for a wide range of document and data
manipulation tasks. 

And dont get me started on the raft of applications and/or application
instances that have expensive database backends (purchase cost / system
resource or admin labour wise) when all they need is a decent filesystem
and structured content ....

> It also means that I don't
> need to write the parser (of course this argument doesn't hold if you're
> Steve Ball :-)

All hail Steve "lets write our CMS in xslt" Ball - he is a guru  8-). 
I know he will gladly accept offerings at the TCLXML alter to ease his
pain ;-) 

And I'd me amiss not to take this opportunity to remind everyone that as
a Steve and I are very busy these days earning a quid with our company,
so any help in writing parsers and assorted peripheral stuff is most
welcome ...



Peter Farmer            |  Custom XML software   | Internet Engineering 
Zveno Pty Ltd           | Website XML Solutions  | Training & Seminars
http://www.zveno.com/   |   Open Source Tools    |   - XML XSL Tcl
Pet...@zv...  +------------------------+---------------------
Ph. +61 8 92036380      | Mobile +61 417 906 851 | Fax +61 8 92036380

Re: [Tclxml-users] How to generate an XML document using TCL

[ski <sk...@eD...>]

> And dont get me started on the raft of applications and/or application
> instances that have expensive database backends (purchase cost / system
> resource or admin labour wise) when all they need is a decent filesystem
> and structured content ....

peter, if a small amount of time could be invested, and you
think it of any value, please "do start" on a simple example
of where you have used XML for an application.

help me [and others?] understand its "calling" so to speak.
my reseach has indicated that it can have value, but not in
Sunil's scenario [and yes, i agree not enough info was given].

thanks

-ski

Re: [Tclxml-users] How to generate an XML document using TCL

[Philip E. <pe...@li...>]

Steve Cassidy wrote:
> 
> One of my main motivations for using XML as a serialisation format is that it 
> removes the need to invent a new format and write a parser for it.  I'm bad 
> at inventing new formats and when I've done it I've always found a little 
> later that I need to extend it in some way that I didn't forsee. XML makes it 
> much more likely that I'll be able to do that.  It also means that I don't 
> need to write the parser (of course this argument doesn't hold if you're 
> Steve Ball :-)


Ah, but parsers are easy... interpreters are the hard part.

Re: [Tclxml-users] How to generate an XML document using TCL

[<Ste...@zv...>]

ski wrote:
> 
> > > I need to generate an XML document using a tcl script, how do i
> > > go about generating the same ?
> 
> as i read Sunil's post [and Steve's answer] i wondered out loud:
> "why XML?" Sunil talks of inventory data, can i assume a RDBMS
> holds this information?
> 
> Sunil suggests [reading between the lines] the end result is to
> view this inventory data with a browser. so again, "why XML?"
> 
> i have yet to write one line of XML. i use PHP to extract the
> proper data from any RDBMS and dispaly it in a browser. there
> is no 'middle' step. there is only [almost] real time access
> to the REAL data in the database.
> 
> how does tcl and XML help in this scenario?

I don't think Sunil gives enough information about the application
to answer this question (at least in a meaningful way - we can always
debate the issues regardless ;-)

The typical answer in this scenario is that the application is
using XML as a data exchange language.  XML is not necessarily the
best way to *store* data (an RDBMS may be a better solution, 
my favourite DBMS would be MetaKit) but it is an excellent language
for *transmitting* data.  The benefits of using XML for data exchange
are many, but include platform- and language-independence,
structuring of data, etc, etc.

The fact that Sunil wants to display the data in a browser does
not preclude XML - you can do client-side transformations using XSL.

Cheers,
Steve Ball

-- 
Steve Ball            |   XSLT Standard Library   | Training & Seminars
Zveno Pty Ltd         |     Web Tcl Complete      |   XML XSL Schemas
http://www.zveno.com/ |      TclXML TclDOM        | Tcl, Web Development
Ste...@zv...  +---------------------------+---------------------
Ph. +61 2 6242 4099   |   Mobile (0413) 594 462   | Fax +61 2 6242 4099