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The XML.com Interview: Steven Pemberton

May 21, 2003

Steven Pemberton

At the top of the HTML hierarchy stands Steven Pemberton, chair of the HTML working group of the World Wide Web Consortium (W3C). A lover of language, a writer, and an editor, as well as an organizer and a leader in the web community, he has had both subtle and profound influences over the Web, not only in HTML standards, but in concepts that permeate the Web. He has been at the center of the forces that have been guiding the Web for over a decade. I recently had the pleasure of speaking with him at his home in Amsterdam by telephone.

Background

Steven Pemberton was born in England, in the county of Surrey, in the village of Ash, about 30 miles southwest of London. He grew up in St. Albans, about 20 miles north of London. "It was originally a Roman city called Verulamium, so there are a lot of Roman ruins around, a lot of history. I went to St. Albans School; it was founded in 948 a.d.," reminisces Pemberton. He went to university at the University of Sussex, which is located on the south coast of England in Brighton and studied electronics. When he went to college, "you couldn't mix. You either had to go with the arts or with the sciences. I would have liked to have done some languages, as well," says Pemberton. Instead, over the years he studied languages on his own, as a personal interest. "I'm fascinated by languages, that's for sure," admits Pemberton. "I speak French, Dutch, and English and all fairly well and some smatterings of other languages." His interest in languages effected his career and how he approached his work in favorable ways.

Writings

In 1993, Pemberton became editor of the bulletin for SIGCHI (Special Interest Group for Computers and Human Interactions). As editor, he wrote editorial essays: "I wrote those pieces on the last page, sort of opinion pieces." His editorial column, Views and Feelings, ran for five years. He reincarnated the column when he became editor for Interactions. The new column, Reflections, is still running. These published musings of his are very interesting commentaries, many dealing with linguistics and computational linguistics.

Pemberton has also co-authored a couple books, one entitled Pascal Implementations: The P4 Compiler and Interpreter (Ellis Horwood 1982), "which to my great pleasure was translated into Japanese," boasts Pemberton. "I've recently put that book on the Web in its entirety and it's turned out to be quite popular." His other book was The ABC Programmer's Handbook (Prentice-Hall 1990). It's on the programming language ABC, which Pemberton was instrumental in creating.

The ABC's and Views

"ABC was designed to be easy to learn and easy to use," explains Pemberton. "Initially, we started off creating it as a beginner language, something like the language BASIC, but much more powerful." Actually, it was useful to programmers of all levels. "It still has a small user base, but the reason ABC is famous is because it formed a basis for Python. I certainly use it all the time, but then I would," confesses Pemberton.

This root of Python, the language ABC and its development into an interface called Views, can be said to be one of the conceptual roots of the Web. "While we were designing ABC we came across many generalized features that we realized could be applied not only to a programming environment, but also to a computer environment. We ended by incorporating them into the Views system, which if you'd see it now, you'd say it's a browser. That's not how we classified it then. We saw it as more of an applications environment. If you put it in terms of today, it has an extensible markup language, style sheets, client-side scripting, and a DOM," Pemberton points out. What's fascinating about Views as an application environment is that in the late 1980's, Pemberton had an understanding of what the browser could be that most would not realize until a decade later as an interface to web services. He says, "Much of what we're doing now with the Web, we were doing more than ten years ago with the Views system, except not over TCP/IP." I suspect that his notion of the browser, and his role as a leader in HTML, has shaped our concept of web applications.

Research

Besides being a software developer, Pemberton is also a systems researcher. Both publications he edited were about the study of computer and human interactions. In his employment with the W3C, he conducts meetings and research into web standards and usage. For his other employer, CWI (Centrum voor Wiskunde en Informatica), he's a researcher. "All of my research comes from the viewpoint of how to make systems easier to use," says Pemberton. "I'm very interested in usability and I apply that to the Web. It's also part of the design of HTML: you not only have the authors of documents -- you want usability for them -- but also the underlying architecture must support usability so that it shows through to the end-user, the person doing the browsing."

W4G and W3C

Before the W3C, when CERN was responsible for HTML, Pemberton organized two workshops at the first conference about the Web. Eventually, he says, "it became clear that the people at CERN were going to MIT to form the World Wide Web Consortium. We were worried that it would leave Europe a bit lost of a center to organize around the Web. So in order to keep research activities going in Europe we organized the World Wide Web Working Group (W4G) within ERCIM, the European Research Consortium for Informatics and Mathematics (which is now the W3C European host)." He chaired the W4G for a few years and eventually became involved in W3C, as well. "I chaired the first W3C event, which was the first style sheet workshop," recalls Pemberton. "Out of that was born W3C's CSS working group, of which I became a member." In that role, he was one of the co-authors of CSS1 and CSS2. Since the CSS and the HTML working groups met in the same location, back-to-back, so that member representatives could attend both sessions, Pemberton joined the HTML working group and helped to develop HTML 4, and in time became its chair.

XHTML

Because of the growth of XML and the deferring of styling to CSS, it was determined that HTML would mature no further than HTML 4. "When we published HTML 4, the group was then basically closed. Six months later, though, when XML was up and running, people came up with the idea that maybe there should be an XML version of HTML," says Pemberton. Therefore, he was asked to conduct a workshop on the future of HTML and how it might relate to XML. He recalls that "it was a successful workshop where there were clear directions that the participants felt that HTML should take: XML had something to offer HTML and HTML had something to offer XML." Consequently, the HTML working group was reformed, with Pemberton as chair, to develop XHTML, XML compliant HTML. Inevitably, forms activities was spun off into a separate working group. "The members who were only interested in forms, were coming to HTML working group meetings, spending days doing nothing of interest to them," explains Pemberton. He became chair of the Forms working group, too.

For some, the reason for XHTML may not be apparent. Pemberton says, "The point in the first place was to create a new version of HTML that would be as close as possible to HTML 4, but expressed in XML. We took the existing definition of HTML and made the minimal number of changes to make it good XML." This may seem persnickety, but they had immediate and future objectives. "The initial advantages were very small," Pemberton says, "but we knew there would be greater future advantages. It would mean that you would be able to combine XHTML with other things and get something sensible out of it. We're just seeing that happening now with browsers."

It takes time to decide on standards and for browser vendors to adapt. "We have a time-line of about four-to-five years. When we produced XHTML in 1999, many people didn't see the point. It didn't actually give you any new functionality at that moment, but we knew it would in the future. Now, there are browsers that allow you to combine XHTML and SVG in a single document, for instance. This was part of the expected design, that once browsers started recognizing different namespaces, they would start processing combinations of those namespaces in a principal way. The theory was to create an XML version of HTML so that when the technology caught up with us, as it were, you could start doing extensible and interesting things with it." "It was a way of giving people a chance to use XML," he adds, "sort of a step over the line, before XML really had reached a critical mass."

As for XHTML 2.0, Pemberton says, "The second step, now that we've got an XML version, is to take what we have and to clean it up, identify problems of the old HTML, create fixes for those problems, more usability, accessibility, internationalization, device independence, and to add new functionality that people have been looking for, that they need and have been doing up to now with scripting." This includes functionality like XForms that allows more possibilities on the client side. The working draft for XHTML 2.0, incidentally, is available. Pemberton says that he hopes for a "last call" this summer.

Closing Thoughts

In closing, I asked Pemberton for his thoughts about the future of HTML: "XHTML is now being implemented, and implemented well, in many different browsers, and popping up in lots of unexpected places like cellular telephones, televisions, refrigerators and printers. In some ways an impediment to the full adoption of XHTML is IE (Microsoft Internet Explorer), since its HTML and XML engines are not well integrated. However, there there are some things coming up that make me think IE will evolve into a shell that won't be doing much processing itself. It'll just be a way of combining different markup languages via plugins," says Pemberton.

As for the Web itself, he says, "I think that we're only at the early stages of the development of the Web. In a sense, it has disappointed me that it has gone so slowly, but I've learned to live with that slow movement. I believe there are some advantages to it in that people are reviewing these things and we're getting a lot of community buy-in of what's being done." With leaders like Steven Pemberton, I agree that we are probably in the early stages of the Web and can expect to see spectacular developments in time.