September 2004 Archives

Leaving Japan for a while

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Am going to Cambridge and attend to XMLOpen 2004, to learn English^W the latest XML technologies. After that, vacations :-) Am looking forward to my first visit to Europe. Will be in London, Brussels (currently a dinner with Gert is planned), and Heidelberg. I'll appear again on 1st Oct, in Ximian office, and will spend most of that month there.

new Microeconomics by Krugman/Wells

I found that the forthcoming Microeconomics book by Paul Krugman and Robin Wells contains a sample chapter on Technology, Information Goods and Network Externalities [pdf], refering to CTEA. Nothing should be new to Lessig readers though.

XPathDocument Changes

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As a sincere ex-law student the worst thing I dislike is false advertisement and unfair trade. And now am spending my time on persuading people saying that copyright is a natural right (sigh). I wonder if I should directly tell the fact that the origin of exclusive right had started just from British book companies.

I put my translation of Miguel's Longhorn Changes into Japanese. You can read it from here. There are no or few people who share the ideas for that matter with Miguel in Japan, so this translation should be informative for Japanese developers.

I had been saying that developers won't use XPathNavigator. I don't have any statistics, but it was obvious, like Avalon and XP. Actually, as a developer who had spent much time on debugging XSLT that is based on XPathNavigator rather than DOM, I don't believe that XPathNavigator is better for practical development, while don't deny that XPathNavigator is cool.

It is a while ago, but there were announcement on System.Xml.XPathDocument being reverted. No wonder, and no need to be afraid. XPathEditableNavigaor is said as still remaining. Only XPathDocument is eliminated. The voices saying that "XPathDocument rocked!!" are really ignorable. XPathEditableNavigator is much easier than XPathDocument because it doesn't have to support transaction (AcceptChanges() and RejectChanges()). XPathEditableNavigator can be implemented over XmlDocument.

(I have no idea how XPathEditableNavigator will be provided though.)

To my feelings, to be IRevertibleChangeTracking, XPathDocument must have been like XmlDocument that might contain sequential text nodes, otherwise it must had too-complex internal change states. It was too unnatural for XPathDocument which is so close to XmlDocument to be able to be much faster. There should be actually little performance difference between XPathDocument and XmlDocument (MS XPathDocument must be based on tree node model unlike our DTMXPathNavigator which is based on document table model).

Some guys say that XmlDocument is 10x or more slower than XPathDocument. It is totally not practical. To my knowledge, it only applies to some kind of reverse-axis queries such as preceding-sibling::*. It is because XmlNode does not have reference to PreviousSibling. If XmlNode is going to have such reference, then its performance should not be different from XPathDocument. Since now that Microsoft XML team publicly said that they will improve XmlDocument, they could make such changes.

Editable XPathNavigator from XPathDocument is still annoyance for such people like me who found that read-only document structure is faster than editable one (I was being forced to implement slower XPathNavigator just for such a silly change). But I won't care. Our internal use of XPathNavigator will be still faster DTMXPathNavigator.

There were another degrading discussion saying that XmlDocument's SelectNodes() will suck with XmlNamespaceManager. That is really not true. Now SelectNodes() should be able to accept IXmlNamespaceResolver like XPathDocument (XmlDocument will be improved, no?) and thus they could write like "theNode.SelectNodes(xpath_string, new XmlNodeReader (theNode))". Or even XmlNode could implement IXmlNamespaceResolver (there are already similar methods like GetPrefixOfNamespace()).