DOMS Collection Access Control **
Context
The implementation of access control in the DOMS. This pattern builds upon the Access Control Planning pattern, and is a more concrete version of these principles.
Description of pattern
DOMS can ensure Access Control (AC) on a "object" level of granularity, thus objects pointing to files containing multiple "streams" of content, will need a system , that varies in AC rights will need. This pattern describes that system.
Problem description
Many collections will contain a lot of split up data, imagine for instance a Newspaper collection, each page will have its own document as part of a section again a part of a newspaper, which is part of a newspapers accumulated editions.
Likewise many born-digital formats contain a lot of layered data in the files, one example is the MPEG-4 format used in the televised materials collection, each file is 3hours long and contain several streams of video as well as textual information about the programs.
Solution
The data model should accommodate the restrictions of the access control system, this is done using shards, the shards describes the parts that make up the object on which access is being controlled.
Consider next
The creation and splitting of data is of importance, is it possible to split the data in such a way that it can be presented without modification? If not what can be done to make the re-assembly of shards easier?