Professional Archive Application Format
MPEG doc#: N11008
Date: October 2009
The purpose of the PA-AF is to provide a standardized packaging format for digital files. This packaging format can serve as an implementation of the information package specified by the reference model of the open archival information system (OAIS). In addition, PA-AF can also be used as an intermediate or exchange packaging format for any kind of multimedia content.
Overview of technology
PA-AF provides a standardized packaging format for digital files. It specifies a metadata format to describe the original structure of digital files archived in a PA-AF file, context information related to a PA-AF file and digital files archived in it, necessary information to reverse the pre-processing processes applied to digital files prior to archiving them in a PA-AF file, and a file format for carriage of the metadata formats and digital files.
Advantages of using ISO/IEC 23000-6
Advantages offered by the PA-AF compared to other conventional data archival software such as tar, zip, etc are as follows.
The PA-AF provides comprehensive metadata to model context information of files archived in a PA-AF file. Context information plays an important role in understanding what data is being archived in a PA-AF file. Without good context information attached, archived data may have less value or in extreme cases become useless.
The PA-AF provides a flexible mechanism to accommodate context information specific to an application domain. Context information other than one that defined by the PA-AF specification can be included in a PA-AF file. An example of such application-specific context information is METS metadata.
The PA-AF provides a flexible mechanism to process input files prior to archiving them in a PA-AF file. The PA-AF does not specify any mandatory pre-processing tools or modules [data compression, data protection, data integrity checking (authentication of originality), and data governance validation checking] prior to archiving Content Information but does specify a mechanism to describe the use of such pre-processing tools or modules. In this way, a PA-AF file creator can choose specific pre-processing tools that suit his preference.
The PA-AF supports cross-platform file extraction. Because the PA-AF preserves the structure and value of original file attributes in a platform-independent way, files archived in a PA-AF file can be extracted to any other target platform besides its original platform. For example, files archived under Microsoft TM FAT32 file system can be extracted to other file systems, e.g., on Linux or Mac OS, seamlessly.
The PA-AF file design supports separation of metadata and files being archived. A PA-AF file can contain only metadata, while files being archived can be stored in one or more archived files. This feature can be applicable for a very large archival system where there are many large files to be archived. The advantage of this design is that it provides a feature to browse a set of archived collections by accessing only one file (the file that has the metadata) and provides a link to the desired archive file.