This article covers distribution options for EPUB 3 content. EPUB 3 is the latest version of the EPUB format, a widely used and easily manipulable format for representing digital publications. If you are a content publisher distributing content indirectly via retailers that support EPUB 3 as an ingestion format then you don’t need to worry directly about how readers will consume your publications. That’s your reseller’s problem, not yours. But if you need to distribute content directly to consumers, then you need to think about how your readers will get and consume this content and potentially develop your own consumer-facing solution(s) to enable that consumption.
Stepping back, there’s really only three ways to deliver any kind of digital content experience to users: files(documents), apps, and websites. EPUB can be readily used to support any of these three fundamental delivery options.
Files
Files are the original form of digital content. Some argue that their sell-by-date is past and that in a cloud-based world everything will become a dynamic experience for consuming data fragments…with no on-going need for “reified” document files. But judging by all of our personal hard drives, files certainly don’t seem to be going away yet and much of our cloud usage seems to be devoted to sharing these files via consumer services like DropBox. When it comes to long term digital content consumers repeatedly have expressed a preference for downloadable files that they can store and consume whenever they want, including of course when they are not connected to the Internet. This also means reading can take place that is not under the control or scrutiny of corporate entities or Big Brother.
The most natural way to distribute EPUB content to consumers is as .epub files that they can download and read on their choice of EPUB-compatible reading systems just as .pdf files are downloaded and read on whatever PDF viewer a reader has installed. These files can be simply links on webpages, for example. But there is a difference in that PDF was invented by Adobe Systems as the file format for Adobe Acrobat and for over 20 years the Adobe Reader Software has been the assumed-by-default option for reading PDF files. Now, there are many other options for reading PDF, including PDF viewers built in to Web browsers like Chrome and Firefox and operating systems like OS/X and iOS. But it’s still quite common to see a “Get Adobe Reader” badge when you see a link to PDF files. There is no such vendor-specific default option for EPUB reading. Adobe does, in fact, provide an eBook reading application for Mac and Windows PC – Adobe Digital Editions – but it is only one of may such applications. So, if you are going to directly distribute EPUB files you probably want to think about which EPUB reading systems your readers are likely to have or be willing to install, test your content with these systems and recommend these reading systems to your customers. Hopefully EPUB will end up as widely supported as PDF and built-in yo browsers and operating systems.
Note – About Digital Rights Managements – DRM
When delivering EPUB files to consumers one consideration is whether the files needs to be protected technologically against redistribution or other un-permitted uses. There is an active debate about the usefulness of technologies that attempt to enforce this type of protection, which are typically referred to as Digital Rights Management (DRM) systems. The issues differ by market segment and use case. For example some publishers don’t try to restrict redistribution of eBook titles that a consumer purchases, but do expect downloaded eBook titles loaned by libraries to automatically stop working when their loan period expires (which requires DRM technology to accomplish). In any case the EPUB standard does not define a particular DRM scheme, but instead provides a more general encryption framework on top of which vendors can add their own encryption technologies. The result is that some .epub files – those protected with a particular DRM – can only be consumed on reading systems that support that type of DRM. If you are a copyright owner who directly distributes EPUB publications, or specifies requirements to distributors who do so on your behalf you may need to consider the pros and cons of utilizing DRM technology versus other options such as “watermarking” content with personal information about the customer who bought it and a notice that it’s licensed only for that customer’s personal use.
Apps
Of course, in addition to downloadable files you may want to offer your readers custom apps for reading your content, either as a general application that supports a number of articles, issues or titles or title-specific applications that are specific to a particular publication.
One reason to create apps is to simply take advantage of AppStore distribution channels. If you want to be in a particular AppStore, you need to have a native app for its platform. Another reason is to deliver a native-optimized experience, that looks and performs like other native apps and takes advantage of native platform APIs. A third reason is to differentiate the experience your readers have with your content. If you deliver content as a file or website, you are at the mercy of whatever reading system or web browser the user has installed. If you deliver an app you are providing the content together with the overall experience. Delivering content as an app may be an indirect way to get DRM protection, as apps are often, but not always, “locked” to a given system when they are installed. Last, but not least, if you deliver content as an app you don’t have to worry about whether or not your consumer has an appropriate reading system available – you are taking care of that for them.
A variety of open source solutions and commercial software providers offer software development kits – “SDKs” – that facilitate creating custom applications that support EPUBs. One that is being collaboratively developed by a number of major industry players is Readium SDK (see http://readium.org). While most of these SDKs are focused on developing general EPUB reading systems, they can be utilized to develop title-specific apps and it’s likely that specialized solutions to facilitate this will be available in the near future.
Websites
Files and apps have been around since the dawn of computing but, of course, these days websites anchor most people’s content consumption. EPUB is designed to “package” Web content into portable documents so it may seem counter-intuitive to consider delivering EPUB content as web pages but it actually has some pretty compelling advantages. Of course, from a consumer perspective, consuming content in a web browser means there’s nothing to download or install. From a publisher’s perspective, you can retain an umbilical cord to your reader for dynamic communication and analytics. By developing your core content as EPUB publications you can de-couple that authoring from the process of deploying a browser-based reading experience with that content. In effect EPUB can become the “contract” between your content production team and your website deployment team. Of course many other formats could be used for that “contract”, including PDF but EPUB has the advantage of being based on HTML5 and CSS…i.e.. it’s a web-native format. Other formats like PDF require either a major format conversion process to turn it into something that can be deployed in a browser, or a very heavyweight client-side rendering program. PDF.js for example is an open source project for reading PDF files in the browser. It runs to over 2MB of JavaScript code. Readium.js is an open source project for reading EPUB 3 files in the browser and its core library is only 20KB, 100 times smaller. A number of other similar solutions are available (with both commercial and open source options) or if your EPUB content will be limited to use of certain features it’s not too hard to write your own browser script for handling content.
That is not to say that all Web content should start life as EPUB. That would be silly. For online-only web apps, dynamic content and small content “nuggets” there’s not necessarily any good reason to go to the trouble of creating a publication packaging of that content. But if you have content that is long-form, has a linear reading order (a beginning, a middle and an end) that might benefit from the option of paginated display, and where the content can be logically separated from the experience of delivering it, then EPUB via the browser may be a good option. Of course, if your content only needs to be read online in the browser, there are other options for structuring such content (CMS systems such as WordPress and Wikis for example). But if you also need to create eBook files that can be disseminated through distribution channels and read offline, and/or your apps with that same content then using EPUB for all three distribution channels may be be a compelling way to modularize your production and delivery work streams and reduce your overall costs, even if your articles and other content nuggets are originally stored in a CMS system or Wiki. In fact CMS and Wiki systems are beginning to add support for EPUB (see the Wikipedia Book Creator for one example of Wiki-based EPUB support).