XML With Style: eBooks and XSL-FOs

March 2, 2000

Simon St. Laurent

Although the XSL specification is still in development, some implementations for XSL Formatting Objects are emerging. Two new projects demonstrated at XTech 2000 use XSL to present XML content with sophisticated formatting.

Yomu describes XSL and XML for Electronic Book Publishing

The XML family of standards provides the foundation for Yomu's Æsop electronic book browser technology. Integrating XML, XSL, XSLT, XLink, and Cascading Style Sheets, Æsop implements the Open eBook (OEB) Specification. Readers can explore and annotate books in the Æsop browser, which Yomu will be making freely available.

OEB provides a packaging mechanism for assembling XML and other resources into a presentation. This can then be navigated much like a paper book—in a sequence, with a table of contents—although the electronic nature of the content makes it possible to create alternate navigation paths and search the content. OEB uses XML to describe the contents of an electronic book, the primary path through the document (the "spine"), and alternate readings ("tours").

Æsop uses W3C XML technologies to present its content: XSL and XSLT for presentation (with support for much of CSS as well), and XLink for annotations and connections. While Christopher Maden noted that Yomu has had to do some extra work to ensure that XLink links work properly when XSLT transformations are applied to documents, the core of the browser is standards-based. The tools used to connect related trees in order to maintain XLink support may eventually be submitted to the W3C as well.

Deborah Hooker, Vice President of Engineering at Yomu, said that they would be giving away the general browser. "Most people don't want to pay several hundred dollars for a device and then more for books. There are people for whom that's a perfect approach, but there's a huge audience that publishers want to reach that won't do that."

Internationalization support is extensive, with support for proper flow of different scripts, bi-directionality, and vertical text. The name "Yomu" itself comes from a Japanese verb meaning to read, suggesting that non-Western languages will receive high priority.

Æsop will be available for PCs, Palm devices, and Macintosh, and Hooker suggests that more platforms will be targeted as well. Æsop is still in active development, as are some of the specs on which it is built, and the timeframe for shipping these products is still tentative.

For more information visit Yomu's web site.

RenderX demonstrates XSL Formatting Objects Rendering

RenderX was demonstrating its commercial FO2PDF formatting objects rendering engine on the exposition floor. David Tolpin, product manager, described this technology as "the missing link in a chain of technology from XML repositories to final media presentation."

In addition to the prototype engine, RenderX's developers are building a Java version of the same engine that will include support for the latest XSL drafts, as well as SAX and DOM inputs. Describing the changes currently being made in the specification, Tolpin said that although RenderX still has some catching up to do, he felt that most of the changes implemented similar functionality to earlier drafts and that bug-fixing should help development along.

The technology demonstration presented at XTech isn't available for direct public browsing, but instructions for exploring it further are available at the RenderX web site.

For more information see FO2PDF at RenderX's web site.