one answer to these questions is the following:
changes in the data structure demand less reprogramming if the data model is
in xml.
imagine you remove field 2 - without xml, you have to change your parser...
with xml
you dont have to change anything...
imagine you have a new field:
in xml you can ignore the new field or implement it whenever...
without you'll have to parse differently again...
as for style, in xml, the logic is the same as the data model. if you use
other xml
features like xlt etc, you'll have similar advantages...
add a little complexity to your program will definitely reduce maintenance
later...
imoho...
-----Original Message-----
From: Dave Cragg [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, April 18, 2001 11:06 AM
To: [EMAIL PROTECTED]
Subject: Re: XML everything
At 9:00 pm -0400 17/4/01, andu wrote:
>I looked at info on different messaging software the other day and came
>across "Jobber" which is "open source".
>What distinguishes it doesn't seem to be a new technology or philosophy
>but the fact that it's all XML: header information, the message itself
>and client-server control data.
>XML has great advantages at operating with data which is displayed but I
>never understood the usefulness of it when it comes to managing data
>"behind the scene".
>Why would one use "<username>andu</username>" instead of "username:
>andu" and stuff like that in a header? Same goes for webDav. The
>overhead of parsing and transmitting at least twice the length of data
>seems unacceptable to me.
>I'd like to hear what other people think on this subject.
>
I guess the appeal of XML is its generality. You can use it to
describe anything from publishable documents to conventional
database-like data.
But I think you're right about the overheads. If your data is
limited to unique fields (user name, id, etc.), and you know when and
how it is going to be used, then why bother with XML. On the other
hand, if you're not sure when you start out how the data might
eventually be used, it might be safer to follow the crowd.
I'm facing this problem right now. Here's a description. (Excuse the
ramble.)
I've been revising a language teaching program which consists of a
large number of lessons, each one a Metacard stack. The plan is to
convert the "content" of the lessons into XML. This makes sense, as
the lessons can be easily repurposed. From the same XML source, the
lessons can be played interactively in Metacard, published in hard
copy, and even played interactively with other tools (e.g. Flash).
But none of the "final formats" uses XML directly. In the Metacard
lessons, the XML is parsed when the lesson opens and is put into
Metacard properties, variables, etc. From that point, the xml is
never referenced again. For the printed copy, the XML tags are
replaced with rtf formatting code (using Metacard of course) and
output as a formatted Word document that is then printed to PDF.
Using XML for the lesson content probably makes good sense. But the
program also has to output various student data such as test results,
lesson progress, etc. Currently, this is done in typical key/value
style. E.g.:
[GENERAL]
userid=xxxx123
lastname=Cragg
firstname=Dave
[TEST_RESULTS]
recenttestdate=2001,4,1
recenttestscore=0
etc.
Should I change this to use XML? Right now, I can't see any good
reason to, so I probably won't. But I think I'm likely to face the
question, "Why aren't you using XML for this?" My answer right now
is a shrug of the shoulders. So what do you think? Should I change it
to XML or not?
Cheers
Dave Cragg
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