It seemed that creating production level XSLT stylesheets that convert DocBook into ePub would help publishers who adopt ePub as their eBook format. Of course we’re developing the stylesheets as part of the open-source DocBook XSL stylesheets, which gives anyone using an existing distribution an easy migration path.
So Adobe is donating my time to help with this task. Of course I’m not the only one involved, Keith Fahlgren (over at O’Reilly Media) is also contributing. There’s also the help and guidance from the docbook-apps discussion list. And there’s always room for review and feedback.
The approach is the following:* Create a new ‘html2xhtml.xsl’ stylesheet. This stylesheet operates on other XSL stylesheets, and contains all the changes that need to be made to the ‘HTML’ set of stylesheets to generate validating XHTML 1.1.* Create a customization layer on top of the XHTML output stylesheets. This customization layer would provide the rest of the XML that goes into the epub. (It generates the NCX and OPF files, and tracks all the entries in the DocBook TOC so that they can be used in the NCX.) The customization layer turns out to be something that anyone who’s successfully using the DocBook XSL will be well-versed in. It’s a common idiom amongst the DocBook community, and so lends itself well to this task.* Create a sample Ant file that provides the packaging. It uses an Ant ‘zip’ task to make the epub file. It also adds the CSS files, which probably would be supplied by the user, into the package as well, and would have a commented section that shows using the epubcheck to validate the final output.At this stage were still putting things together, and while you could track our progress over at sourceforge, there’s nothing really to test yet (I’ll post again when there is testable stylesheets.) Developers that are interested can see the branch although there’s some major pieces missing.