Monday  2002-07-01   Software

What ails native XML databases?

In the beginning, XML database vendors would tell a story:

As more and more data are stored in XML format, it is best to store and process XML in environment and platform specifically designed for XML using technology built for this express purpose ie XML database.

Problem was that almost nobody bought this story. There were few reasons to put data into XML databases because of

• stickiness of data ie most of data are stored in non-XML format,
• high cost of transforming existing and future data to XML,
• concerns over interoperability with existing data,
• and lack of capable, usable technology eg basic query language.

Kimbro Straken (of Apache Xindice nee dbXML fame) writes there will be room for embedded XML databases but native XML databases are doomed given that Oracle 9i and other RDBMS are for all intents and purposes native XML databases.
 
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Monday  2002-07-01   Software

XML schema languages, PSVI, Infoset

Out of many candidates for XML schema language W3C XML Schema is the only one to introduce PSVI or post-schema validation infoset. PSVI is returned by schema processor analogous to how Infoset is returned by parsers. Infoset is "an abstract data set ... that provides ... definitions to refer to the information in a well-formed XML document"; PSVI works for validated and well-formed XML document. PSVI provides not only information on validation of an XML document but also type information on elements and attributes as well as their default values. And yet even W3C working group does not have use cases!

PSVI inevitably raises many questions:

• Will majority of XML users use it? If so how?
• What is the cost of producing PSVI? Who pays for it?
• Doesn't it change XML as we know it to something different?

Especially PSVI's type system already generates strong objections and dissents like "One typesys to rule them, and in the darkness bind them."

PSVI will affect the future of XML profoundly, or will it?
 
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Monday  2002-07-01   Software

Against W3C XML standards

Simon St Laurent summarizes the most contentious issue facing XML digerati: "Rising Rebellion Against W3C XML Schema". Many developers are looking for alternative schema languages because they are afraid of massive complexity of Schema standard. Currently there is no clear winner.

Schema is already well-established and making far-reaching impacts on other standards eg SOAP, XPath 2.0, XSLT 2.0 and XML Query 1.0. Because XML Query is trying to be statically typed query language, it needs Schema; because Query is to embed XPath, XPath 1.0 is to accomodate Schema and become 2.0; because XSLT uses XPath, it too becomes 2.0. As XPath and XSLT get "upgraded" they will be incompatible with the original 1.0. Even though some part of the upgrade may benifit users, much of the changes are happening for the sake of XML Query 1.0.

Unfortunately XML Query 1.0 when it's delivered some time in the future will not have CRUD capabilities. (It cannot update nor delete.) Once native XML database vendors disappear, who will use this language?

Maybe this year (2002) we will get an answer to the question of schema language after two years of debate and also see MathML, SVG, SMIL and others finally become usable and useful after many years of promises. There are still six months left.
 
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Sunday  2002-06-30   Software

IETF's guideline on XML

"Guidelines for the Use of XML within IETF Protocols" is currently in draft stage but it is still useful for XML application developers.

The guideline can be summarized as "keep it simple, stupid" or KISS. Avoid processing instructions, entity declarations and references; be careful with namespaces; beware of whitespaces; think twice before using attributes or even worse their default values, and so on.

When will W3C provide a guideline on what processing XML means?

Sunday  2002-06-30   Software

eclectic - the XML-DEV weblog

Because XML digerati are rather loquacious, mere mortals are indebted to Leigh Dodds' "eclectic", the XML-DEV weblog for summary. Many links to XML issues that appear in short notes on 2002-07-01 come from "eclectic" and many articles by him and others from xml.com.