Package org.osid.repository

package org.osid.repository

The Open Service Interface Definitions for the org.osid.repository service.

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 buildingResourceType to a buildingSubjectType ) 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.



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