BY EVAN KOBLENTZ
Technology Editor, TMC Labs™

Wireless: An Evolution Of Languages

This isn't a traditional CTI@Home column. You won't find me rambling about the latest SOHO unified messaging application or some new Palm goodie. Instead, this week is all about Web development for non-PC browsers. The result? At a minimum, you'll be the envy of the cocktail party geeks with your newly-found knowledge of the latest wireless standards.

In her column from December last year, TMCnet.com's Dara Bloom Mirsky discussed how WAP technologies can be used in the enterprise. Since then, I've been privy to (or a victim of, depending on your point of view) numerous vendors' press releases regarding WAP, along with its cousins -- XML, XHTML, HDML, WML, and Bluetooth, to name a few. I figure that, inevitably, some reader is going to ask me to explain these technologies, and to do so at a level beyond what the acronyms stand for. So, rather than give that fictitious reader an ad-hoc answer, I will refer them to this column you're about to read.

This week, I spent a few hours on the telephone with media representatives from the World Wide Web Consortium -- a.k.a. W3C -- and from the WAP Forum. Read on: This stuff is cooler than most people realize.

The first thing that you need to understand is HTML 4.0 (Hypertext Markup Language) and its parent, SGML (Standard Generalized Markup Language). As explained in the W3C document:

SGML is a language for describing markup languages, particularly those used in electronic document exchange, document management, and document publishing. HTML is an example of a language defined in SGML.

SGML has been around since the middle 1980's and has remained quite stable. Much of this stability stems from the fact that the language is both feature-rich and flexible. This flexibility, however, comes at a price, and that price is a level of complexity that has inhibited its adoption in a diversity of environments, including the World Wide Web.

HTML, as originally conceived, was to be a language for the exchange of scientific and other technical documents, suitable for use by non-document specialists. HTML addressed the problem of SGML complexity by specifying a small set of structural and semantic tags suitable for authoring relatively simple documents.

So, that's SGML: powerful, but complicated. HTML is less powerful, but easy.

Enter XML (Extensible Markup Language) and XHTML. As explained in the same document, the XML 1.x  is "a means of regaining the power and flexibility of SGML without most of its complexity." Meanwhile, XHTML 1.0 is the merger of XML and HTML: "a family of current and future document types and modules that reproduce, subset, and extend HTML." The W3C document cites some of the advantages for sites coded in XHTML 1.0 (instead of in HTML 4.0):

XHTML documents are XML conforming. As such, they are readily viewed, edited, and validated with standard XML tools.

XHTML documents can be written to operate as well or better than they did before in existing HTML 4-conforming user agents, as well as in new, XHTML 1.0 conforming user agents.

XHTML documents can utilize applications (e.g. scripts and applets) that rely upon either the HTML Document Object Model or the XML Document Object Model. [www.w3.org/TR/xhtml1/#ref-dom]

As the XHTML family evolves, documents conforming to XHTML 1.0 will be more likely to interoperate within and among various XHTML environments.

The W3C document at hand continues to note interesting things. Consider this:

Alternate ways of accessing the Internet are constantly being introduced. Some estimates indicate that by the year 2002, 75% of Internet document viewing will be carried out on these alternate platforms Ultimately, it will be possible to develop XHTML-conforming content that is usable by any XHTML-conforming user agent.

As the use of XHTML moves from the traditional desktop user agents to other platforms, it is clear that not all of the XHTML elements will be required on all platforms. For example, a hand held device or a cell-phone may only support a subset of XHTML elements.

See how it all makes sense now? First came SGML, then HTML, then XML, then XHTML. Each markup language and each version improved the power-to-simplicity ratio. The latest languages also focus on non-PC accessibility, since it's becoming clear that traditional computers will not be the main way to access the Internet in the near future -- witness PDAs, Internet appliances, mobile telephones, audio ISPs, auto PCs, television set-top boxes, even wearable PCs and refrigerators.

The W3C is doing other telephony-related work as well, all with the goal of more and better Web access. For example, there's the Mobile Access project, the Voice Browser project, and the Web Accessibility Initiative. I will elaborate on these three projects in the July issue of Internet Telephony magazine.

But it doesn't end here. Taking the XML a step (or two or three) farther, the WAP Forum has developed WML (Wireless markup language), which is the successor to the current and more primitive HDML (Handheld Device Markup Language). I strongly encourage all of you to read the excellent WAP and WML white paper (in Adobe Acrobat format), as well as the joint W3C/WAP Forum white paper.

On top of the network and transport layers, WAP and the WML features a security layer (Wireless Transport Layer Security (WTLS)), transaction layer (Wireless Transaction Protocol (WTP)), session layer (Wireless Session Protocol (WSP)), and application layer (Wireless Application Environment (WAE)). Of course, there's no physical layer -- we are talking about wireless here!

More interesting still, there is a WAP API for voice/data integration, which is called the WTA (Wireless Telephony Application). To quote from the white paper:

The Wireless Telephony Application (WTA) allows application developers to initiate phone calls from the browser and respond to network events as they occur. The WTA API accomplishes this by providing an interface to the local and network telephony infrastructure. The local interface allows WML and WML Script to access a specific set of telephony functions, such as a function call to dial a phone number from the mobile handset. The network interface allows an application to monitor and initiate mobile network events, so that the application can take action or update information based on these events. This functionality can be used to keep an updated list of the phone numbers dialed into an active conference call.

Back to the W3C: they just never stop working. Consider the work on something called XSL (Extensible Style Language) which will detect what kind of device you're using and report it to the XML application. The application will in turn transmit the proper code (whether it's XHTML or WML) to your browser.

In addition to all of these languages, there's Bluetooth to consider. Bluetooth is a wireless technology that will run parallel and in conjunction with WML and the others. However, Bluetooth can do great things on its own, like automatically detect a node when another node is placed within wireless range, and it can synchronize data between nodes without requiring any user input -- for example, walk into your garage or office while carrying your PDA, and it will automatically synchronize your email and address book with that of your desktop PC or auto PC.

With the right tools, Webmasters will soon be able to write a single set of code that is viewable from any browser on any kind of device, and it will appear (or sound) to the end-user that the site was designed specifically for that particular browser and device. This is a lot of information to digest, and it's certainly not easy to master. I hope that, by reading this column, you've become more fluent in your understanding of next-gen wireless technologies. Once enough developers learn how to control these tools, the next step is to write killer applications for them. Will you be the first?

Evan Koblentz welcomes your comments at ekoblentz@tmcnet.com.