XML Schemas

An XML schema describes the “type” of an XML document, typically expressed in terms of constraints on the structure and content of XML documents of that type. These constraints or rules are defined above and beyond the basic syntax rules which qualify a document as being an XML document.

As an analogy in Object-Oriented Programming, think of an XML schema as a “class” and XML documents conforming to the schema as “instances” or “objects” of that class.

Several languages have been developed specifically to express XML schemas. “Validating Parsers” are used to validate the conformance of XML documents to XML schemas. The most common type are “DTD-Validating Parsers”, which support the Document Type Definition (DTD) language. DTD is a schema language of relatively limited capability, native to the XML specification.

Resources:

• DTD at Wikipedia
• RELAX NG at Wikipedia
• RELAX NG Home Page
• Schematron at Wikipedia
• ISO Schematron Home Page
• Designing a New Schema with XML Design Pattterns
• W3C XML Schema Requirements

Day 054 – This is Not Cool! :-(

_Captain’s Log, StarDate 2007.08.29-00.58_

I was just uploading some more photos to flickr when I realized that it has a 200-photo limit on its photostream for free accounts. That is not cool at all!! Just when I thought all this Web 2.0 stuff was working out well for me…

Halp! I don’t want to let google take over the world!

Day 053 – Kudos to Self!

_Captain’s Log, StarDate 2007.08.28-00.52_

All that hard work seems to be paying off. In a rather unusual turn of events, I was at a collague’s desk when the company’s MD happened to stop by for an informal chat. At the same time, our manager happened to be passing by and she mentioned to him that she’s been hearing only good words about our work Talk about being in the right place at the right time…

Day 052 – The Corridors of Power

_Captain’s Log, StarDate 2007.08.27-00.39_

Today I was showing a couple of people around office and we were walking through a long, rather narrow corridor when a group of people in business suits started walking in from the opposite direction. Amidst the crowd I noticed a vaguely familiar face. It took me a moment to realize that the same face was on the cover of a magazine I was reading earlier – our company’s Group President!

The best part was that I looked him in the eye and wished him a good afternoon, and he had the humility to wish me back – not with the typical nod, but with a smile and in as many words. I really admire that in leaders. One of my biggest fears is that arrogance will one day (far in the future) get the better of me. How do men weilding so much power remain so humble? On the other hand, if they were not humble, polite and well-mannered, they would probably not be weilding so much power anyway…

XQuery

XQuery is a query language semantically similar to SQL, designed to query collections of XML data. From W3C: “The mission of the XML Query project is to provide flexible query facilities to extract data from real and virtual documents on the World Wide Web, therefore finally providing the needed interaction between the Web world and the database world. Ultimately, collections of XML files will be accessed like databases”.

Of all the possibilities that XQuery potentially offers, one of the most interesting would be its use in solving the Web’s “offline problem” and giving users seamless access to their data with or without an Internet connection.

Resources:

• XQuery at Wikipedia
• W3C XQuery
• Tutorial at w3schools.com
• FLOWR (FOR, LET, WHERE, ORDER BY, RETURN) at Wikipedia

XQuery is a superset of XPath, which is an expression language for addressing parts of an XML document and possibly computing values based on its content.

XPath Resources:

• XPath at Wikipedia
• Tutorial at w3schools.com
• Tutorial with many examples
• Tiny XPath – Implementation in C++

Day 051- Another Lazy Sunday

_Captain’s Log, StarDate 2007.08.26-00.25_

I learnt how to use a steam iron today, at the cost of burning my finger a little bit. Well, atleast the ironed shirts look pretty good

I got some more work done in the afternoon and went to receive a couple of teammates at the airport in the evening. My efforts at managing my time better seem to be paying off, I’m getting a lot of unpleasant, long-pending tasks over with these days. I always argued with myself that the “work” has to end sometime. The end is still nowhere in sight, but I’m more hopeful than ever now. I can walk away from it whenever I want to, but ideally I would like to get it done. There’s a lot I’d like to get done, let’s see how much of it actually materializes. For me, life is one big exercise in management – fitting in an infinite number of tasks in finite time.

Day 050 – A Twist of Fate, and Another Dream Come True

_Captain’s Log, StarDate 2007.08.25-17.08_

We were planning to go Downtown for shopping, and to catch our last glimpses of Downtown Montreal in its full glory before the impending fall (autumn) sets in. By a strange twist of fate, I got late and missed my buddies at the Mall. Later, I found out that they went to watch a Hindi movie, which suited me perfectly fine because I’m not the kind to pay money to be locked up in a dark room with strangers eating popcorn watching scantily-clad women and formally-dressed men running around trees.

With the effort of dressing up and leaving the Hotel having already been taken, and with nothing better to do, I decided to check out a supposedly have-it-all store called Canadian Tire here. And thus ended up spending the best 5 hours of my life in a shopping mall, ever. The massive store stocks everything a man (often secretly) desires – camping equipment, outdoor clothing, sports equipment, automobile accessories/tools/spares, hardware, tools, powertools, nifty little tools and gadgets, electricals, electronics, gardening equipment, knives and weapons – you name it! I was overwhelmed by the range, the variety within each category, and how well-organized the whole thing was. I spent hours looking at stuff that I had till now only seen on TV, marvelled at its simplicity and beauty, and wondered why we don’t have the same thing available in India. I finally got to see and touch something that has been an enigma to me since childhood – duct tape. Yes, plain ol’ grey duct tape. I still haven’t been able to figure out why we don’t have duct tape in India. My personal favourite, though, was – brace yourself – flavouring for charcoal barbecue fires. You drop in some of it into the fire and supposedly some of the flavour wears off on the food you’re cooking. What kind of a jobless mind did it take to invent something like that?

Day 049 – Lakshmi Pooja

_Captain’s Log, StarDate 2007.08.24-17.31_

I changed my daily routine today to squeeze in some exercise time in the morning before leaving for work. Makes more sense.

I found out in office today that Varmahalakshmi Pooja is celebrated in south India today. Being the only one (or perhaps one of the few) carrying a photo of Laksmi Maa (that was for Diwali, BTW), I invited everyone over in the evening to my room for Pooja. Some folks prepared and brought sweets, while some others showed up with dripping hair straight out of the bath. In all, about 15-17 showed up. No one knew what to sing for the Aarati, so each person sang whatever little they knew. All in all, it went off rather well.

Day 048 – Caught in the Rain

_Captain’s Log, StarDate 2007.08.23-17.42_

We went out shopping for shoes and beer today and got caught in the rain on the way back, and ended up having tomato soup instead of beer before dinner. We didn’t find any shoes, either. But I did buy some clothes from a sale at Sears.

Day 047 – Some Serious Work

_Captain’s Log, StarDate 2007.08.22-17.46_

I’ve been doing some serious research into XML lately (as in “late into the night”), and will keep posting results here. I’m trying to take full advantage of this time to get as much work as I can get done to serve my evil plan of world domination