Repository

An Asset represents some digital content. Example assets might be a text document, an image, or a movie. The content data, and metadata related directly to the content format and quality, is accessed through AssetContent. Assets, like all OsidObjects, include a type a record to qualify the Asset and include additional data. The division between the Asset Type and AssetContent is to separate data describing the asset from data describing the format of the contents, allowing a consumer to select among multiple formats, sizes or levels of fidelity.

An example is a photograph of the Bay Bridge. The content may deliver a JPEG in multiple resolutions where the AssetContent may also desribe size or compression factor for each one. The content may also include an uncompressed TIFF version. The Asset Type may be "photograph" indicating that the photo itself is the asset managed in this repository.

Since an Asset may have multiple AssetContent structures, the decision of how many things to stuff inside a single asset comes down to if the content is actually a different format, or size, or quality, falling under the same creator, copyright, publisher and distribution rights as the original. This may, in some cases, provide a means to implement some accessibility, it doesn't handle the case where, to meet an accessibility requirement, one asset needs to be substituted for another. The Repository OSID manages this aspect outside the scope of the core Asset definition.

Assets map to AssetSubjects. AssetSubjects are OsidObjects that capture a subject matter. In the above example, an AssetSubject may be defined for the Bay Bridge and include data describing the bridge. The single subject can map to multiple assets depicting the bridge providing a single entry for a search and a single place to describe a bridge. Bridges, as physical items, may also be described using the Resource OSID in which case the use of the AssetSubject acts as a cover for the underlying Resource to assist repository-only consumers.

The Asset definition includes some basic copyright and related licensing information to assist in finding free-to-use content, or to convey the distribution restrictions that may be placed on the asset. Generally, if no data is available it is to be assumed that all rights are reserved.

A publisher is applicable if the content of this Asset has been published. Not all Assets in this Repository may have a published status and such a status may effect the applicability of copyright law. To trace the source of an Asset, both a provider and source are defined. The provider indicates where this repository acquired the asset and the source indicates the original provider or copyright owner. In the case of a published asset, the source is the publisher.

Assets also define methods to facilitate searches over time and space as it relates to the subject matter. This may at times be redundant with the AssetSubject. In the case of the Bay Bridge photograph, the temporal coverage may include 1936, when it opened, and/or indicate when the photo was taken to capture a current event of the bridge. The decision largeley depends on what desired effect is from a search. The spatial coverage may describe the gps coordinates of the bridge or describe the spatial area encompassed in the view. In either case, a "photograph" type may unambiguously defined methods to describe the exact time the photograph was taken and the location of the photographer.

The core Asset defines methods to perform general searches and construct bibliographic entries without knowledge of a particular Asset or AssetContent record Type.

AssetContent represents a version of content represented by an Asset. Although AssetContent is a separate OsidObject with its own Id to distuinguish it from other content inside an Asset, AssetContent can only be accessed through an Asset.

Once an Asset is selected, multiple contents should be negotiated using the size, fidelity requirements, or application evnironment.

A Composition represents an authenticatable identity. Like all OSID objects, a Composition is identified by its Id and any persisted references should use the Id.

A repository defines a collection of assets.