“When faced with the need either to consolidate archives or to migrate them to new generations of storage technology, media companies traditionally have been forced to perform the costly and time-consuming integration of archive systems and other systems,” said S. Merrill Weiss, chair of the SMPTE Working Group on AXF. “Now, by abstracting the underlying technology of digital storage, AXF not only supports interoperability among today’s discrete storage systems regardless of the operating and file systems used, but also future-proofs digital storage so that content remains available despite changing formats and storage technologies.”
Designed for operational storage, transport, and long-term preservation, AXF was formulated as a wrapper, or container, capable of holding virtually unlimited collections of files and metadata related to one another in any combination. Known as “AXF Objects,” such containers can package, in different ways, all the specific information different kinds of systems would need in order to restore the content data. The format relies on the Extensible Markup Language to define the information in a way that can be read and recovered by any modern computer system to which the data is downloaded.
AXF Objects are essentially immune to changes in technology and formats. Thus, they can be transferred from one archive system into remote storage—geographically remote or in the cloud, for instance—and later retrieved and read by different archive systems without the loss of any essence or metadata.
AXF Objects hold files of any kind and any size. By automatically segmenting, storing on multiple media, and reassembling AXF Objects when necessary, “spanned sets” enable storage of AXF Objects on more than one medium. Consequently, AXF Objects may be considerably larger than the individual media on which they are stored. This exceptional scalability helps to ensure that AXF Objects may be stored on any type or generation of media. The use of “collected sets” permits archive operators to make changes to AXF Objects or files within them, while preserving all earlier versions, even when write-once storage is used.
The nature of AXF makes it possible for equipment manufacturers and content owners to move content from their current archive systems into the AXF domain in a strategic way that does not require content owners to abandon existing hardware unless or until they are ready to do so. In enabling the recovery of archived content in the absence of the systems that created the archives, AXF also offers a valuable means of protecting users’ investment in content. By maintaining preservation information such as fixity and provenance as specified by the OAIS model, AXF further enables effective long-term archiving of content. Resilience of data is ensured through use of redundant AXF structures and cryptographic hash algorithms.
AXF already has been employed around the world to help businesses store, protect, preserve, and transport many petabytes of file-based content, and the format is proving fundamental to many of the cloud-based storage, preservation, and IP-based transport services available today.
Many individuals and organizations have contributed to the development of AXF. The project was led by S. Merrill Weiss, president of the Merrill Weiss Group. Principal contributors included Brian Campanotti of Front Porch Digital (acquired today by Oracle), Karl Paulsen of Diversified Systems, James Snyder of the Library of Congress, Steve Posick of ESPN, William Hayes of Iowa Public Television, David Hostetter of Oracle, Merrick Ackermans of Turner Entertainment Networks, and John Eremic and Robert Wolfe of HBO.
The AXF standards document is now available to subscribers and for purchase in the SMPTE Digital Library at http://standards.smpte.org. Further information about SMPTE and its work is available at http://www.smpte.org.