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Friday, December 28, 2007

Fedora 3.0 Beta Features Content Model Architecture (CMA)

A Beta release of "Content Model-driven Fedora 3.0" has been announced
by the Fedora Commons Project developers. The CMA is described as a
powerful, new integrated structure for persisting and delivering the
essential characteristics of digital objects in Fedora while simplifying
its use. Fedora Commons is the home of the unique Fedora open source
software, a robust integrated repository-centered platform that enables
the storage, access and management of virtually any kind of digital
content. Prior implementations of the Fedora Repository utilized a set
of specialized digital objects as a functional and persistence framework.
All of these objects conform to the same basic object model. Digital
objects in CMA are conceptually similar in prior versions of Fedora
though some important implementation details have changed. Fedora still
implements a compound digital object design consisting of an XML
encapsulation (now FOXML 1.1) and a set of bitstreams identified by
the "Datastream" XML element. We can also assemble multi-object groups
of related digital objects as before using semantic technologies. In
the CMA, the "content model" is defined as a formal model that describes
the characteristics of one or more digital objects. A digital object
may be said to conform to a content model. In the CMA, the concept of
the content model is comprehensive, including all possible
characteristics which are needed to enable persistence and delivery
of the content. This can include structural, behavioral and semantic
information. It can also include a description of the permitted,
excluded, and required relationships to other digital objects or
identifiable entities. "Following the rules of Fedora identifiers, the
identifier of the CModel object can be encoded within a URI. We will
describe the rationale for this decision in a later section but this
approach provides two immediate benefits: (1) it provides a scheme
which works within the Fedora architecture with minimal impact, and (2)
it is compatible with the Web architecture, RDF and OWL. We can even
build functionality using just the knowledge of the identifier without
creating a content model. Having a uniform method for identifying a
digital object's class maximizes interoperability..."

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