Readium: EPUB 3 reference implementation with WebKit
With Readium, the International Digital Publishing Forum (IDPF), is working on an open source reference implementation for displaying digital publications that comply with the EPUB 3 document standard. From a technical perspective, WebKit will play a major role as the system's rendering engine, but the IDPF also plans to align its efforts with the WebKit project's specifications in terms of content – the IDPF said that, in the long term, it is even conceivable that the planned development will be integrated with the browser engine.
The plan includes developers eventually being able to use Readium (or its components) to integrate standards-compliant support for EPUB files into their applications. The IDPF said that for this reason the system mainly targets developers rather than end users.
The standards organisation noted that it considers EPUB to be a suitable portable "Open Web" format, and that support for the format within WebKit itself is conceivable in the long term. However, the IDPF added that, in consideration of its partnership with the project, it aims to avoid actions that would be negatively viewed by WebKit stakeholders, and that it is aware that EPUB support is presently not a priority for the WebKit developers. The organisation said that it can imagine falling back on a fork of the WebKit project with Readium once the EPUB system reaches maturity.
The source code for a proof of concept implementation of the Readium library is available, under a BSD licence, via GitHub, and developers can also install that library as a Chrome extension (version 15 or newer of the browser is listed as a basic requirement for rendering EPUB contents with Readium). A feature complete implementation, complete with support for Android is expected by the middle of the year.
The first industry supporters have already been found and include Adobe, Google, Barnes & Noble, Kobo, O'Reilly, Samsung and Sony. Version 3 of EPUB is in direct competition with Amazon's Kindle Format 8 and Apple's new iBooks container; these formats are also based on (forthcoming) web standards such as HTML5 and CSS 3, but they each encapsulate the standards in proprietary formats.