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December 2003 Archives

Xml 2003 Reflections - Adam Bosworth Keynote

[Another look back at the XML 2003 conference last week. I feel sortof blogspherically incorrect in waiting a week to write down these thoughts, but I wanted to let them bounce around a bit, and look at what others wrote.]

Adam Bosworth of BEA delivered the opening keynote address on Wednesday. He started by reminding us of the dream that XML geeks shared back in 1998: Information should not get lost in presentation. Actual XML practice has to some extent diverged into two separate streams -- documents on one hand, and application data on the other -- but together they have helped take back the world from the "hideous complexity and fragility" of information presented in .DOC, .EXE, etc. files.

I started to summarize the talk itself, then came upon Matt May's excellent near-transcript . I'll just elaborate on a few points that resonated with me.First, Bosworth notes that one of the negative aspects of the current XML world is that the KISS (Keep It Simple, Stupid) principle is being widely ignored, as XML and Web services technologies are becoming extremely complex. Bosworth has pointedly noted the complexity of W3C XML Schema and XQuery in the past; this time he said something like "there's only one guy in our company who *really* understands WSDL" ... and "we don't need all these layers of coordination/orchestration specs on top of SOAP, we need something like a 'SOAP cookie'." It's heartening to see more and more people pick up on the theme that the XML family of specifications is too complex, since I've been beating this drum for a long time now. It's definitely time for some serious refactoring of the the family of XML specs, and that won't happen until more people of Bosworth's stature start telling the unpleasant truths about what a few thousand person years of Design By Committee will do to a technology that used to be simple. The video clip from Bosworth's presentation in Jon Udell's weblog has my favorite quote from the talk: After admitting that 50 people would come up with 75 different ways of building distributed systems ."Some will win, some will lose. That's just fine. It's called evolution. It works really well. It's why we're all sitting here today." Maybe a bit of Darwinian Refactoring is what is called for on this stuff.

Another major theme in the keynote was that XML developers are asked to use "APIs from Hell." For example, a programmer working with a purchase order in XML format must deal with events, or child/sibling nodes in a tree, rather than application-level concepts such as products and quantities. Hmm, that's a posting in and of itself, because it ties in with a town hall meeting on storing/querying XML that turned into a discussion of XML APIs. More later.

Probably the most unconventional topic Bosworth spent time on was the importance of getting XML data models and APIs suitable for handling the synchronization of intermittently connected devices to Web-based master databases or applications. He noted that he spends much of his business week using only his Blackberry device. Effective use of such web-enabled, but slow and UI-challenged devices will require better synchronization tools: queries are difficult to generate with a handheld UI, and their limited bandwidth (if connected at all) means that it is important for queries to be very optimized to return back only the information the user really wants. Since this is so far beyond the state of the art, it may be easier for the device to anticipate the types of data the user will want, and trickle than information into the device in advance, as bandwidth is available, rather than on demand.

Bosworth presented a slide outlining a "Mobilized Data Model" that might help guide work on this. I suspect that many other listeners were also intrigued, but a bit mystified by this-- a planned demo wasn't ready in time for the conference. It has, however, generated some interesting discussion on the Web, not so much on the still-fuzzy details of the data model, but on the deeper issues. For example, Tim Bray notes that he is skeptical of the basic assumption behind the widespread need for synchronization, since "the trend is clear: anyone who wants to will be able to have a fast pipe that's always on." I'm not sure which side I come down on, but there is definitely two world views here: Those who assume that there will be a significant amount of data on the handheld device that must be synchronized with a central repository, and those who assume that in general the remote device will be able to query the central repository for the data it needs for a given task. Bosworth did offer one data point that might argue against Bray's position: At best, in the best-served places in the world a GPRS (General Packet Radio Service -- used for "always on" connection to the Internet by mobile devices) request takes 1 second to fulfill, and more if any significant amount of data is transmitted. Unless we get a WiFi network that is as extensive as the GPRS network today, it's not clear that the "fat pipe" assumption is realistic.

Another point that Bosworth has explored, not so much in his speech but in his weblog. How can one address the difficult challenge of synchronization without falling into the trap of complexity that will not scale to the Internet, or even work on a limited power and bandwidth device? He's asking a lot of questions about REST in the weblog, getting lots of answers, but one gets the impression that they are not satisfactory.

Inspired by a posting by Vanessa Williams, I'll put in a plug for the ideas behind JXTASpaces (sortof tuplespaces/Javaspaces using XML rather than objects) as a way of bridging the gap between the web services ideas that Bosworth talked about and the REST stuff that intrigues him. (Williams doesn't make the link to Bosworth in the posting, but has done so privately) . Kimbro Staken picks up the thread and mentions how an XML DBMS that supports XPath can make the template lookup feature of tuplespaces easy to implement if XML documents are the "tuples." I think they are definitely on to something here -- See Robin Cover's summary of some technologies and discussions, including some comments by me. The one point that's most relevant to synchronizing mobile devices is that coordination via "spaces" allows loose coupling in time as well as space -- not only can components in a distributed system employ different platforms, languages, and native data formats, they don't even have to be running at the same time. On the other hand, product ideas such as Ruple went nowhere and even the open source JXTASpaces project is a not exactly thriving. Is this just an idea whose day has not yet come, perhaps like hypertext before HTML? Or is there not really a "there" there? I'm pretty sure that if any application domain is tailor made for an XML Spaces approach, it's intermittently connected mobile devices!

Finally (just when I thought I was finally done blogging this speech!), Joe Chiusano asks about the apparent contradiction between Bosworth's focus on simplicity and BEA's co-authorship of a somewhat daunting list of Web services specifications. It will be interesting to see if Joe gets an authoritative answer from BEA; my guess is that they are telling it like it is in a recent press release that suggests [at least in my reading between the lines!] that customers are giving them the message that the current way of doing things is too complex.

XML 2003 reflections - day 1

This is the first of several reflections on what I think I learned here at the XML 2003 conference in Philadelphia. Sorry if it's too XML-geeky and not of sufficient interest to Java people, but I think a lot of what I heard people talking about have considerable relevance beyond the XML community they were aimed at.

Jon Udell gave a keynote speech on Tuesday that pierced the jaded, slightly cynical shell I've acquired after about 8 years in the XML world. He didn't talk about "maybe someday..." or "if only ...", he showed what a little imagination can do with the widely deployed XHTML, CSS, and XPath technologies today.

He began with an explanation of why the idea of an XML document that can be shared by different application is "magical," using two speeches by Bill Gates to illustrate the point. 10 years or so ago, Gates' slogan was "information at your fingertips," in which information workers could bring together text and data from a variety of applications and easily find, reuse, and revise it. The vision was a powerful one, but we are only beginning to realize it today. Part of the reason for the delay, Udell argued, was that in the OLE architecture that Microsoft promoted (and in the OpenDoc architecture of its rivals), each application owned its own proprietary data, and OLE/OpenDoc provided a means by which they could talk to each other. This worked to some extent, but created tight couplings (I'm not sure if Udell used that term) among the applications, object models, and operating systems and programming languages that support them.

In a more recent version of Gates' stump speech, the key idea is a "universal canvas" enabled by XML. Rather than applications communicating to access each others' proprietary data, they share a common XML representation of the data -- some may be numbers manipulated with a spreadsheet, others text manipulated by a wordprocessor, still others structured data manipulated via a forms interface. This vision is already very close to reality in Microsoft's Office 2003 product (and Udell's keynote was followed by a presentation from Adobe that demonstrated their very similar vision in action).

What makes XML a good "universal canvas"? In Udell's words, "contextual metadata is XML's gift to mankind." To demonstrate this, he showed how he had been eating his own dogfood in the presentation slides, which were being displayed in Mozilla on a Mac, produced with ordinary XHTML, with CSS styling, and some script. He showed some queries that exploit Mozilla's XPath support on data that wasn't really designed to be queried, but exploits the metadata that XHTML authors create without thinking about it -- links, attribute values put in to support CSS styles, etc. When the idea of XML-defined context is more explicitly supported, as in Kimbro Staken's Syncato weblog tool (or is it an "XML fragment management system?"), the power of XML's ability to model context and XPath's ability to query it becomes even more apparent. In any event, knowing that one will use XPath to retrieve information in the future motivates one to think about the structure of content as one writes -- creating the contextual metadata magic without much extra effort.

Udell went on to talk about how these advantages can be extended to email and instant messages, in which most real business communication takes place (and thus where the real content is created). We need to build tools and products that tap the small packets of structure and context and pull it into useful business information. Although Microsoft Office's XML support does not extend into Outlook, there are ways to archive email and IM in XML, and Udell challenged the audience to help devise real products and integrations to exploit the potential this would create. In any event, we don't need new standards, or a solution to the thorny issue of the diversity among flavors of RSS/Atom, to make progress -- XHTML, CSS, and XPath provide the basics of what we need. Udell argued that we need to figure out how to use what we have in a smarter way, and to "smuggle" metadata into content because it leverages the universal urge to make things look cool.

So why did this pierce my cynical shell? Most would agree that we need more metadata on the Web for it to live up to its full potential -- that's the very premise of the Semantic Web effort in which Tim Berners-Lee has invested much of the W3C's resources (and credibility). On the other hand, the historical difficulty of getting real people to put metadata in their content is believed by many to doom such efforts to failure. (Cory Doctrow's essay is the most colorful and cogent, if widely reviled, statement of this position). Udell's insight is that we can leverage the technology we have, salted by human vanity, to get usable metadata without technological breakthroughs or unrealistic demands on humans.

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