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= DOMS Collection Access Control ** =

== Context ==
The implementation of access control in the DOMS. This pattern builds upon the [[../../Access_Control_Planning|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 [[../../Data_Shards|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?