XML: Five Years and Counting - An AppDev Guide
Believe it or not, XML turned 5 last month. But if you think the W3C's XML work is winding down, you'd be wrong -- on many fronts. IDN takes the occasion to bring developers/sysadmins up to date on W3C's plans, and on the latest resources for XML and the XML Schema Definition (XSD).
Believe it or not, XML turned 5 last month
. Integration Developer News takes the occasion to bring developers/sysadmins up to date on the latest resources for XML and the XML Schema Definition (XSD).
And, even after 5 years, if you think the W3C's (World Wide Web Consortium's) work on XML is winding to a halt, you'd be mistaken on many fronts. In fact, the W3C's XML Activity is chartered through September 2003, with a flurry of test suites, working drafts and pending recommendations still in the works. For intance:
- The XML Core Working Group is stil working on defining an XML processing model.
- The XML Schema Working Group is working on gathering requirements for a next release of the XML Schema language.
- The XML Query Working Group continues work on the XML Query Language, a way to provide flexible query facilities to extract data from real and virtual XML documents on the Web. This includes publication of XQuery and also XPath.
[To get involved in any of these efforts, contact Liam Quin, XML Activity Lead at email@example.com
But there are many more groups working to make developers' experiences with XML and the XML Schema Definition Language (XSD) easier and more productive. Integration Developer News takes the occasion to bring developers/sysadmins up to date on the latest resources for XML and the XML Schema Definition (XSD).
Microsoft's MSDN provides a very thorough Developers' Guide to XSD, setting out steps and sample code for how developers can define the structure and data types for XML documents. This set of XSD resources at MSDN reviews highlights and tips for W3C's XML Schema Part 1: Structures Recommendation for the XML Schema Definition Language; and Part 2: Datatypes Recommendation (for defining data types used in XML schemas).
More XML/XSD Resources:
O'Reilly's XML.org presents a very thorough article that shows developers how to use XSD correctly to navigate "controlled vocabularies" -- or schema changes to "enumerated lists of element-attribute values." In his article, "Managing Enumerations in W3C XML Schemas," author Anthony Coates contends that when outside interests control schema definitions -- even well-intentioned standards groups (like ISO, W3C, etc.) developers must be on the defense against the need to rewrite, retest and reassign the schemas in your code. Coates provides real examples with real code samples that developers can use.
XML-Deviant Kendall Grant Clark says the topics of conversation on XML-DEV revolve around two camps of people: one which thinks aspect N of XML is a wart, the other which thinks N is an elegance. See which is which, and why even in a world of auto-generated XML, it still matters to core XML-based web services development at http://www.xml.com/pub/a/2003/03/19/deviant.html.
Developers are shown how to transform XML in steps using a preliminary XSLT to transform XSD into XML that is easier to transform into generated code. In an article from Visual Studio Magazine, Denver-based MVP Kathleen Dollard shows how using XSLT's DataSet and DataTable lets developers "hide some of the ugliness of restructuring data." Dollard also shows how XSD is used to create XML files containing metadata, and then to perform the code-generating transformation.
In this Top XML Tutorial by Kurt Cagle, learn how to navigate the main XSD Structures, including Conceptual Framework (to abstract the process of defining schemas; Schema Components (to create formal schemas from a strictly formalistic standpoint); XML Implementation (to implement XML representation of the formal grammar); and Constraints (which deal with ways that a given element or attribute can be constrained to work within a subset of its original domain).
XSD Validation using SAX (or the DOM API) is illustrated in this piece by PerfectXML.com's Managing Editor Darshan Singh. This through step-by-step (with code samples) approach takes developers through the whole process, from deriving stub implementation classes to declaring the methods that we'll use for XSD validation and for counting XML elements.
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