Faster XML ahead?

The Net's top standards body is getting closer to speeding up XML-based software, a move that could benefit everyone from cell phone carriers to television broadcasters to the military.

But critics say the group's favored approach could cause major compatibility problems, among other things.

XML is fast becoming a widely used way of formatting and saving business documents such as purchase orders. But for certain applications--sending data to set-top boxes, for instance, and offering interactive programs on cell phones--representing data using XML is simply too bulky, say proponents for more efficient XML.

"XML has been a victim of its success," said Robin Berjon, of standards group the World Wide Web Consortium, "We've started using it in all kinds of situations that it wasn't designed for."

If XML were zippier, say some, cell phone companies, for example, could meet consumer demand for more complex programs. The Air Force, too, has expressed interest in using speedier XML formats for embedded computing applications, such as those found in fighter jets (click here for related PDF).

A W3C committee recently recommended that the group address the problem by moving away from the traditional way of saving XML data--in text format--and instead create a standard for a binary format. W3C working group recommendations are generally taken up as formal standards efforts, which means the group is one step closer to a major change in the XML standard.

The recommendation still has to be approved by the W3C's Advisory Committee and the W3C's director. But a vote to move forward with a binary XML standard could happen late this summer, said Liam Quin, the XML activity lead at the W3C.

Binarians and contrarians
The issue, though, is already causing controversy among the XML cognoscenti, who worry that significant changes to the specification could cause compatibility headaches and face significant hurdles in getting adopted.

Attendees of a February meeting in Boston argued for different technical approaches to speeding up XML. Some questioned the need to take up a binary XML effort at all, according to people present at the meeting.

We shouldn't "mess around with (XML) just for a short-term fix (when) in the long term, the industry is going to fix that problem naturally," said Eric Newcomer, chief technology officer at Iona Technologies and an attendee of the meeting. Newcomer says current XML performance "is not all that bad" and that the controversy is "reminiscent of the argument about a decade ago, when everyone said the World Wide Web is too slow and it will never take off."

Right now, all the information in an XML document, such as a name and address, is represented as text. Binary formats compress the XML

data into a smaller file but require a specific program to view the information. Several companies have already created binary formats to suit their different operating environments or industries.

For example, Expway has created ways of storing XML data in a binary format for the mobile phone and television industries.

In those industries, bulky XML text documents are not suitable, and as a result, XML is not being widely used, said Berjon, the chair of the W3C Working Group on Binary Characterization and a researcher at Expway. Fast performance is essential for sending data to certain devices, such as set-top boxes, because consumers will not tolerate the slow transmission of programming guides or other information, he said.

Similarly, the mobile communications area is ripe for smaller XML files, argue proponents.

Mobile devices are getting more powerful processors to read more data. But all that processing sucks the life out of batteries, which haven't kept pace with chips on the upgrade front, said John Schneider, chief technology officer of AgileDelta, which makes software for devices to compress and more efficiently handle XML data.

By using XML-based protocols, called Web services, mobile carriers could offer more interactive applications than are available today and help meet consumer desire for games, calendars and so on, he said.

Compelling applications "make a huge difference. It adds a lot of value--the more people can access, the more valuable the information becomes," said Schneider.

Meanwhile, Sun Microsystems launched its own project, called Fast InfoSet, which it says can boost the speed of an XML application anywhere from two to 10 times.

Binarians, unitarians and contrarians
It's estimated that there are at least a dozen binary XML formats already in use or in development today. If it does go ahead with an effort to speed up XML, the W3C will seek to create a single group-sanctioned binary format, rather than have several formats for specific purposes, said Quin.

"We hope if we publish something that meets the needs of many of

these people, they will switch to whatever we publish. And indeed many have said they would do that," said Quin.

Others argue that multiple binary formats are needed. Michael Rys, a program manager for Microsoft's SQL Server database and a member of the W3C's XML Query Working Group, said that Microsoft does not favor the W3C creating a single binary XML format.

In a blog posting following the Boston meeting, Rys said that if there must be a binary XML standard, then the W3C should "do it right."

"There will be more than one binary XML format," Rys wrote. The W3C is "very unlikely to define a format that optimizes a dozen, partially conflicting goals."

Another concern facing the W3C is whether a substantial change to the XML standard, such as a binary XML format, will be widely adopted--or ignored.

To process XML data sent over the Internet, devices need a software program called an XML parser. Existing parsers would have to be upgraded, in the form of a patch or service pack, to make sure computers can read both text and binary formats. Without broad adoption of the specification, software developers will be less likely to make use of the speedier XML.

XML proponents note that the latest XML 1.1 specification has been adopted more slowly than hoped. Microsoft, for example, has decided not to support that specification for fear of causing compatibility problems with applications that use the XML 1.0 standard, according to Rys.

Iona's Newcomer noted that there are several different options for making XML go faster. Some approaches would require a complete rewrite of existing parsers, rather than relatively minor changes with a simpler upgrade path, he noted.

If the W3C votes in favor of pursuing a binary XML standard, a working group could be formed as early as this summer and take up to three years to complete a specification, Quin said. To address concerns and solicit feedback, the W3C is scheduling public hearings at various conferences worldwide.

"This one has some controversial aspects," Quin said, "so I would not like to predict the outcome at the moment."