Remedial XML: For further reading

Well, congratulations, students, you've graduated from our remedial XML course. Before you go, I'd like to provide you with a list of useful resources so that you can continue your studies. Be sure to check back with us here at Builder.com for more material. Now, please remember to collect your volleyballs as you leave.

Get it from the source
As we all know by now, the XML technology standards are managed by the W3C, which should be your first stop when looking for XML information. Sure, finding something particular can be challenging, and the specification documents themselves are surefire cures for insomnia. However, there's no better place to look for answers to implementation or usage questions than the W3C's recommendations and working documents. If you look hard enough, you’ll turn up links to development resources here as well.
After much experimentation, I've found that drilling down on topics in the "W3C from A to Z" listing is more productive than searching the site for a particular keyword. Remember that anything you find here that's labeled "non-normative" is for informational purposes only, and anything that does not have a status of "recommendation" is a work-in-progress and subject to drastic change.
O'Reilly's XML.Com
XML.com features a regular set of columns on general XML development, usually written by authors of O'Reilly-published XML titles. The content is largely language-agnostic, and what isn't concentrates on Perl and Java. Of interest to the beginning XML developer will be the "Essentials" section, which lives about one-third of the way down the page on the left-hand side. It contains a set of "What is" articles that provide introductory information about some of XML's adjunct technologies and tools like XSLT, XSL-FO, XLink, and RDF.
Don't you need a cover page?
The XML Cover Pages is an XML and SGML information portal sponsored by the Organization for Advancement of Structured Information Standards (OASIS). It mostly serves as a repository for documentation and news concerning various XML initiatives and industry standards, although there are also links to general XML articles from various publications, and information about major XML and SGML conferences and events. If you’re seeking information about a particular specification or application of XML technology, the Applications section deserves a look. Likewise, check out the Software section for a list of publicly available software and tools for working with XML.
In need of a pit stop
XMLPitstop.com has a self-proclaimed mission to provide developers with a central location for resources and information about XML. Sporting a large database of links to XML-related tutorials on sites all over the Web, and a very impressive set of downloadable sample applications and examples for your reverse-engineering pleasure, it appears to meet that mission.
With or without milk?
Author Elliotte Rusty Harold maintains Cafe con Leche, as well as the Java information portal Cafe au Lait. It’s another XML portal that appears to be updated more frequently than XMLPitstop.com, and it reports news that is much more developer-centric than that located at The XML Cover Pages. It typically includes major (and not-so-major) product release announcements. Scattered down the right-hand side of the page you'll discover links to sample book chapters (Tutorials), XML specifications, parsers, and other development tools, as well as some sample XML applications.
Big Blue's XML channel
I discovered IBM's developerWorks site several years ago, and it's since become one of my favorite sources for non-Microsoft development information. The XML Zone has an extensive tutorial section that contains introductions to loads of XML-related technology. In addition to these tutorials, the XML Zone features regular columns that often revolve around real-world development projects, written by real-world developers.
Looking for something specific?
More of an industry news portal than a developer information site, http://www.xml.org/, nevertheless, has a few things to offer the budding XML developer. Foremost is the searchable Schema/DTD registry I mentioned earlier in this series, which houses hundreds of industry standard Schema/DTD definitions. This site also manages the XML-DEV e-mail discussion list and hosts a searchable archive of the same.
Knocking on heaven’s door
One of my all-time favorite developer resource sites, Programmers Heaven.com has a dedicated XML Zone, although it's somewhat hidden under the database section. Programmers Heaven sports news, very active discussion forums, links to informational articles from all over the Web, and downloadable source code. Check out our review of Programmers Heaven to see what it offers beyond answers to your XML questions.

Stay on top to stay ahead
These sites will help you keep your XML skills fresh and up-to-date. Check them regularly for new developments and you’ll stay ahead of the game.