SummaryΒΆ
Repository Open Service Interface Definitions repository version 3.0.0
The Repository OSID provides the service of finding and managing digital assets.
Assets
An Asset
represents a unit of content, whether it be an image, a
video, an application document or some text. The Asset defines a core
set of definitions applicable to digital content, such as copyright and
publisher, and allows for a type specification to be appended as with
other OsidObjects
.
Asset content, such as a document, is defined such that there may be multiple formats contained with the same asset. A document may be accessible in both PDF and MS Word, but is the same document, for example. An image may have both a large size and a thumbnail version. Generally, an asset contains more than one version of content when it is left to the application to decide which is most appropriate.
The Asset
Type
may define methods in common throughout the
content variations. An example asset is one whose content Types
are
“Quicktime” and “MPEG”, but the Asset
Type
is “movie” and
defines methods that describe the move aside from the formats. This
“double” Type hierarchy stemming from the asset requires more care in
defining interfaces.
Assets
also have “credits” which define the authors, editors,
creators, performers, producers or any other “role”, identified with a
role Type,
with the production of the asset. These are managed
externally to the asset through another OsidSession
.
Through additional optional OsidSessions,
the Asset
can be
“extended” to offer temporal information. An asset may pertain to a
date, a period of time, or a series of dates and periods. This mechanism
is to offer the ability to search for assets pertaining to a desired
date range without requiring understanding of a Type
.
Similarly, the Asset
can also map to spatial information. A
photograph may be “geotagged” with the GPS coordinates where it was
taken, a conical shape in stellar coordinates could be described for an
astronimocal image, or there may be a desire to may a historical book to
the spatial coordinates of Boston and Philadelphia. Unlike temporal
mappings, the definition of the spatial coordinate is left to a spatial
Type to define. The Repository OSID simply manages spatial mappings to
the Asset.
Asset Tagging
Assets
may also relate to Ontology OSID Subjects
. The
Subject
provides the ability to normalize information related to
subject matter across the Assets
to simplify management and provide
a more robust searching mechanism. For example, with a photograph of the
Empire State Building, one may wish to describe that it was designed by
Shreve, Lamb and Harmon and completed in 1931. The information about the
building itself can be described using a Subject
and related to the
photograph, and any other photograph that captures the building. The
Asset
Type
for the photograph may simply be “photograph” and
doesn’t attempt to describe a building, while the AssetContent
Type
is “image/jpeg”.
An application performing a search for Empire State Building can be
execute the search over the Subjects,
and once the user has narrowed
the subject area, then the related Assets can be retrieved, and from
there negotiate the content.
A provider wishing to construct a simple inventory database of buildings
in New York may decide to do so using the Resource OSID. The
Resource
Type
may describe the construction dates, height,
location, style and architects of buildings. The Type
may also
include a means of getting a reference image using the Asset
interface. Since there is no explicit relationship between Subject
and Resource,
the Resource
can be adapted to the Subject
interface (mapping a building_resource_type
to a
building_subject_type
) to use the same data for Subject
to
Asset
mappings and searching.
Asset Compositions
Asset compositions can be created using the Composition
interface. A
Composition
is a group of Assets
and compositions may be
structured into a hierarchy for the purpose of “building” larger
content. A content management system may make use of this interface to
construct a web page. The Composition
hierarchy may map into an
XHTML structure and each Asset
represent an image or a link in the
document. However, the produced web page at a given URL may be
represented by another single Asset
that whose content has both the
URL and the XHTML stream.
Another example is an IMS Common Cartridge. The Composition
may be
used to produce the zip file cartridge, but consumers may access the zip
file via an Asset
.
Repository Cataloging
Finally, Assets
and Compositions
may be categorized into
Repository
objects. A Repository
is a catalog-like interface to
help organize assets and subject matter. Repositories may be organized
into hierarchies for organization or federation purposes.
This number of service aspects to this Repository OSID produce a large
number of definitions. It is recommended to use the
RepositoryManager
definition to select a single OsidSession
of
interest, and work that definition through its dependencies before
tackling another aspect.
Sub Packages
The Repository OSID includes a rules subpackage for managing dynamic compositions.