Some time ago we posted an overview blog article on Adobe Content Server Permissions. As one of the three follow-up posts, this blog will cover what happens when you apply certain combinations of permissions to a book and try to do certain things with that book. This post in particular will cover reading permissions and is not dependent upon the next two posts which cover copying and printing. However, if you are new to ACS permissions, it may help to read our permissions overview blog first.
We’ll start with the glossary to define some terms, followed by a few use cases. Afterwards we’ll explain some of the caveats and best practices for using reading permissions.
Before getting into things, it might be helpful to cover some basic terminology. Some of these may be obvious, but it’s worth listing them out to clear up any ambiguity between similar terms. (This glossary is the same in the other parallel blog posts, so skip it if you’ve read those.)
ACSM File – the download token generated when the user clicks the GB Link at the store.
Fulfill – to open an ACSM file and have the reader application communicate with the ACS server to download a book.
Open – to “double-click” an ACSM file or to perform a similar device-specific operation on the file, which does not necessarily imply a complete fulfillment; it is possible that opening an ACSM file will result in fulfillment errors in which case a fulfillment may not occur.
Side-load – to copy a book from a desktop reader application (like Adobe Digital Editions) to a tethered device connected via a USB port.
Re-download – to download an ACSM file using a new link; the new link will use the same resource ID and transaction ID (and thus have all the same restrictions) as the original download link, but will count as a “fresh” link as far as link expiration is concerned.
Below are the results of applying certain permissions to a book, then attempting to fulfill and perform actions on the book. For these tests, unless otherwise specified, the books were fulfilled in ADE first on one desktop computer, then an attempt was made to fulfill them on a second computer. Under unrestricted conditions, the book would open fine on both devices.
Reading on any number of devices, 3-minute expiration:
• Book behaves as expected on first device. If attempting to read 3 minutes after fulfillment, ADE gives an “expiration duration” error message.
• If the ACSM file is opened on the second device more than 3 minutes after it was fulfilled on the first device, ADE will give a general “expired” message. This same result occurs with an attempted re-download.
• Opening the ACSM file on a second device before the 3 minutes are up will result in a successful fulfillment. The time remaining will be the difference between 3 minutes and the time since fulfillment.
Reading on any number of devices, absolute expiration:
• The downloaded book has the same behavior as with relative expiration, above.
• The only extra thing to note about absolute expiration is that the book will expire at midnight (12:00 AM/00:00) on the day specified. This is based on the time and time zone of the end user’s device.
Reading allowed on a single device only, device type unspecified:
• Book will always be fulfilled as normal on first device.
• Transferring the ACSM file to a second device and trying to fulfill again will result in a “wrong device” error in ADE. This same behavior occurs if the original download link is used on a second device, or if a re-download is attempted on a second device.
• These outcomes are the same whether a desktop or mobile device is used.
Reading allowed on a single device only, mobile devices only:
• Book will always be fulfilled as normal on first device as long as it is a mobile, non-desktop device.
• As above, transferring the ACSM file to a second device and trying to fulfill again will result in a “wrong device” error.
• Similarly, trying to fulfill the book on a non-mobile device in any way, using the ACSM file, the original link, or the re-download link, whether the book had previously been fulfilled or not, causes a “wrong device type” error.
Reading on any number of devices, specifying multiple device types (standalone, mobile, tethered):
Note: this setup can only be specified through an XML during packaging, not from the Admin Console
• Book behaves as expected on the first device on which it is opened; in this case, a standalone device.
• When trying to side-load from ADE to a tethered device, ADE gives a message like “copy not allowed”. If the ACSM file is copied to the device, the device’s reader will be unable to fulfill the book with a message like “not authorized for this device type”.
• However, if the book is fulfilled on a mobile device first, then the ACSM file is copied to the desktop, the book can then be fulfilled on the desktop without issue.
• It follows that limiting the device type to certain devices, as opposed to allowing it for any device type, may result in one-way behavior. From an ease of use perspective, it is best to limit to one device type or to not set a type limit at all.
Notes on Reading Permissions
After reading these use cases, you should be able to see that there are a few things we can take away from them. First, that a re-download will not “reset” the permissions on a book. If the user wants the expiration time to start over, they will need to make a new transaction; that is, they will need to purchase or check out the book again. This is true even if you change the permissions of the book on your server. The permissions are stored alongside the transaction ID in the database, so the only way for the customer to reset or update their permissions is if they create a new purchase or if you provide them with a new transaction ID manually.
A second point to be made is that limiting the viewing permissions to multiple types of devices may result in asymmetrical behavior. While side-loading in one direction may work, there may be difficulties going in the opposite direction. For this reason, it is best practice to either limit viewing to a single device type or to not limit the type at all.
Finally, keep in mind that there is currently no way to set a limit on the number of devices, aside from one device or unlimited devices. There is, however, a limit on device activations imposed by a user’s Adobe ID or Vendor ID account. This limit is six desktops and six mobile devices at one time, so no book can be read on a truly unlimited number of devices.
That about does it for our more detailed look at reading permissions. The two upcoming blog posts – those regarding printing permissions and copying permissions – will follow this same format and cover specific use cases and caveats for those permission sets.