Books in the Cloud: What is OPDS and Why Should I Care?

Books in the Cloud

One of the benefits of an e-book, over a traditional publication is that it is disconnected from the physical world. It has been virtualized. It is a bunch of bits that reside “somewhere” that you copy onto your reading device which converts it into a visual rendition of the text. The somewhere can be on your PC at home, on a laptop you carry with you, on a thumb drive in your pocket, or stored on a server that you can access through the internet. Once on the internet, the location of the book can no longer be expressed in longitude and latitude, or country and zip code. It is no longer in real space, it is in cyberspace! Since cyberspace evokes scenes from TRON or books by William Gibson, the world marketing minds of the Internet® decided to call it “the cloud.”


The Open Publishing Distribution System (OPDS) is a web service with which e-books can be shared with other connected systems. An OPDS client application can communicate with any server that implements this service. This is how an app on a mobile device, such as Stanza (iOS) or Aldiko (Android), can “get books” from bookstores or libraries.

While OPDS is format agnostic, the reader applications are usually not. As was mentioned in the article Understanding e-Book File Formats, the “universal” format for e-books is EPUB, and most OPDS enabled readers will only recognize e-books in this format. This forces kindle users to get all their books from Amazon. For most, this is not much of a hindrance since Amazon has an enormous selection, and the store is well integrated into the Kindle, but it blocks Kindle users from libraries and small publishing houses (such as WritelyDone). To find something  like can someone write my paper for me in the cloud, you need its web address (URL) and then can you can access it where ever you are, and it can never be misplaced or forgotten on a nightstand.

OPDS in Action

As an example, I’ll go through the process of connecting to WritelyDone’s OPDS service using Stanza on an iPod Touch.

Once the Stanza application is running, select “Get Books” from the icons along the bottom. A list of per-configured book sources appears.

Selecting the “Shared” button from the top row of buttons opens a user configurable list of book sources. In my case, I already had Feedbooks set up, so it shows up in the list. Pressing the “Edit” button allows you to add or remove sources.

After pressing the green plus button to add a source, you can enter the URL of the OPDS catalog you are trying to add. Enter that data and press “Save” and then “Done.” The WritelyDone catalog is now added to the list.

Selecting WritelyDone as a book source opens a screen where you can select from the available content on WritelyDone. The “Bookshelf” option, will contain any of the titles you have added to your bookshelf on, you will be required to log in to view your bookshelf. Enter your WritelyDone user name and password when prompted.

Selecting a book from your shelf, opens a page with a description and a “Download” button in the upper right. After pressing “Download” you will be prompted to confirm the action, and then the download will take place.

Different sources

The process for adding book sources is similar in all readers. All you need to know is the location of the OPDS catalog and you can add a source. Here are some OPDS catalogs to try out