XML Developer Tip
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Interesting XML developments and initiatives
The most recent edition of the XML Newsletter from O'Reilly's XML.com includes a summary article by lead editor Edd Dumbill based on his closing keynote speech at XML Europe in Amsterdam in April, 2004. Entitled "The State of XML," it makes some really interesting and valuable points, and also talks about some equally interesting and potentially valuable XML initiatives now underway to help address some of XML's weaknesses or stumbling blocks.
On the summary side, Dumbill observes that his closing keynote in 2000 (the first time he gave such an address at the XML Europe convocation) remains fresh and relevant today, despite the passing of four years since it was delivered. He also observes that XML appears to have finally taken hold in a meaningful way for all kinds of content, and in most major programming languages, making XML nearly ubiquitous today. My favorite observation of his is that the key questions in 2000 were "What is XML?" and "Why use XML?" whereas today key questions are "What XML applications are relevant to my needs?" and for those still outside the XML fold, "Why aren't you using XML?" This reflects the profound and significant shift toward XML understanding and usage that has affected nearly every major content initiative, most development platforms and environments, and every programming language in widespread use.
That said, Dumbill also defines some key initiatives underway -- about which I'll write more in detail in future XML tips -- that are designed to address some lingering unaddressed issues aimed at further normalizing XML usage. In particular these include:
- How to standardize and simplify what Dumbill accurately describes as "…the mish-mash of processing instructions and attributes" (aka PI, or processing instructions) found at the head of so many XML files and documents? He points at work now underway at the W3C on a standard XML processing model that could help to address this often-confusing situation.
- A document-type independent way of permitting processing tools like those used to implement document presentation (style and appearance, as with various versions of Cascading Style Sheets, or CSS) to find element identifiers within specific documents. In this case, work underway on an xml:id draft is intended to address this situation.
He also talks about how groups outside the W3C -- such as OASIS -- have made notable contributions to the XML community, especially for such popular applications as RELAX NG. (I'd also add mention of things like DocBook and numerous security-related items, but Dumbill raises the issue of uncontrolled Web services proliferation, and argues that Paul Prescod's Representational State Transfer, or REST, model could make such proliferation unnecessary).
Dumbill also raises an extremely interesting issue that's near and dear to me (and many other XML aficionados) -- namely metadata. He also makes the telling point that operating system vendors are also becoming interesting in using XML for creating, storing, and manipulating metadata as well. He notes further that many existing XML tools are suitable for such use, but zeros in on a key issue when he says "The main problem is which terms, schemas, and ontologies to use." Without a standard, consistent framework, individual operating systems (or other implementations) become islands, and will require significant discussion and transformation tools to exchange metadata, which is why he also talks about needs for "the semantic equivalents of XSLT."
All in all, this is a terrific article and, as advertised, provides a useful and vibrant summary of the state of XML. It remains an area of great interest, significant utility, but also of tremendous growth and upheaval. As with any good serial, it leaves us hanging on the edge of our seats, waiting for the next thrilling installment!
Ed Tittel is a VP of Content Development & Delivery at CapStar LLC, an e-learning company based in Princeton, NJ. Ed runs a small team of content developers and project managers in Austin, TX, and writes regularly on XML and related vocabularies and applications. E-mail Ed at firstname.lastname@example.org.