OPDS: RSS for ePub or how to distribute ePub files

Martin Fenner
February 6, 2011 2 min read

ePub is a great format for scholarly content, and there are a number of tools to create ePub files. But creating content is only half the story, at least as important is an easy mechanism for distribution. This is particularly true if your ePub files are not books, but shorter pieces of content: journal articles, blog posts or even output from your ongoing research. RSS or the related Atom protocol has of course become the standard mechanism to publish frequently updated works.

Open Publication Syndication System (OPDS) is a syndication format for electronic publications based on Atom. OPDS is a relatively new format, but is supported by a growing number of (book) publishers, ePub tools and readers. If you want to try OPDS for yourself, pick one the feeds listed here and add the feed as a Book source in the Stanza reader (in the Shared section). Alternatively, install the EPUBReader plugin for Firefox. As you can see, OPDS does more than just list titles with a summary and image, you can also categorize the content by author (or tag), and provide a search interface.

I’m looking forward to the first scholarly publisher that not only provides ePub files of his journal articles, but also makes them available via OPDS. Although OPDS is currently used mostly for electronic books, I think that this is a very interesting protocol for scholarly publishers. Did I mention that OPDS also provides facilities for buying or lending content? And that you probably shouldn’t expect OPDS support in the Apple iBooks application for iPhone and iPad anytime soon as they don’t seem to like distributed content delivery? I would like to see scholarly publishers providing their journal content via ePub and OPDS that can be consumed with one of the many available readers, rather than everybody creating his own little app that only works with a single publisher on a single platform.

OPDS is a relatively simple protocol and similar to RSS should make it easy for everybody to provide his content in catalog form. It should be straightforward to add OPDS support to the WordPress ePub plugin that I released last week, thus making a blog (or blog network) available directly in the ePub reader. While I expect that we will continue to read most blogs via the Web or RSS reader, ePub might be the better format for longer posts and the posts you want to store on your computer.

ePub is a very interesting format for packaging research objects, e.g. the description and data files from an experiment. OPDS would be very helpful as a distribution mechanism for these ePubs, and also works on the small scale of a research group. You can for example use the Calibre eBook management tool – which can create not only ePub files but also OPDS catalogs – together with Dropbox to share your content. The calibre2opds tool also creates an OPDS catalog from the Calibre metadata database but doesn’t require Calibre to run in order to use the OPDS catalog. And the Pincette document management system automatically creates an OPDS catalog for the ePub files dropped into a Pincette folder. I hope that more tools for researchers start to support not only ePub but also OPDS. An OPDS interface to the data produced by your favorite piece of lab equipment (gel documentation system, microarray reader, etc.) would be an interesting sight.