DTD vs. XML Schema

AShocka writes "The W3C XML Schema Working Group has released the first public Working Draft of Requirements for XML Schema 1.1. Schemas are technology for specifying and constraining the structure of XML documents. The draft adds functionality and clarifies the XML Schema Recommendation Part 1 and Part 2. The XML Schema Valid FAQ highlights development issues and resources using XML Schema. This article at webmasterbase.com addresses the XML DTDs Vs XML Schema issue. Also see the W3C Conversion Tool from DTD to XML Schema and other XML Schema/DTD Editors."

Comments

Re:Who needs XML when you got PXML?

[Anonymous Coward]

Better yet, use S-Expressions.
There are tons of parsers available.
markup is simple:
(this_is_the_tag
this is all data
(except_this_is_a_nested_tag with still more data))

Even better still, there are customizable parsers available that can treat these S-Expression as data OR interpret them as program OR a combination of both. One such parser is called "Lisp". Once again, several implementations are available.
Note that things like S-Expressions and Lisp have only been around for 40 years so you might want to give these technologies some time to mature.

Re:All this hype about XML

[sporty]

I year ago we had the XML craze we converted all our internal protocols to XML. I discovered that XML was just a lot of hype about nothing. There is nothing self-describing about it. Or maybe there is, just like the section names in an INI file describe the keys in them...

Great thing about XML, is if you need to convert your communications, you can write XSLT against it to convert it while you convert your XML source.. easily. For instance, one vendor I worked with decided that the old protocol didn't work well anymore, and a ne one would be better. Forget the reasons for the change, good or bad.

I plopped an XSLT processor in front of it. Took minutes to implement. In the mean time, I was able to properly rewrite the XML producing code. So I had some flexibility in terms of patching the protocol quickly, while taking the weeks I needed to fix things right.

As for self describing, what is more self describing than HTML? You see a bold and italics tag around an element, you can easily figure out what style the text would be in. Yes, I know about CSS, but the point is, XML IS descriptive, so long as you use good names. Naming elements a, b and c is just developer fault.

If you use XML to develop a lower level protocol you end up with bloated 10k messages.

If in today's age of gigabit ethernet and cheap parts, you really really need to squeeze that extra bit through, compress the line. Seriously. Simplest case, is using ssh. Hell, it auth's AND encrypts. If you are worried about anonymous access, there are other tools.

The hell I won't

[ttfkam]

Trimming bloat like namespaces and comments? Are you nuts?

How do you embed MathML in another document (like XHTML)? Currently it's with namespaces. How do you propose to do that without namespaces? Just the prefixes? What happens when two different markups use the same prefix? Wups! You're screwed!

No comments? This is supposed to make a better alternative to XML? It won't help readability, and it certainly isn't a major bottleneck during parsing.

Don't want the "bloat" of namespaces and comments? Wait for it... Wait for it... Don't use namespaces and comments in your documents! Wow! What a concept!

Maybe no Unicode in PXML hunh? So much for interoperability for any kind of data. You don't ever want your pet project used in East Asia (or Russia or Greece or most other places in the world) do you? Unicode too bloated? Why not just use ISO-8859-15 (basically ASCII w/ a Euro character -- which incidentally a Euro character isn't available in ASCII)? Oh wait! That's right. You don't want to allow processing instructions, which in XML tell you what encoding is used.

What happens if you want to change some of the basic syntax of PXML? Because you've nuked processing instructions, you can't specify a markup version like you can in XML.

Yes, yes. We've all seen your little pet project. I hope it was just a class assignment.