Many discipline-specific and community-specific metadata standards have evolved to meet the challenge of supporting data management and discovery as well as capturing and communicating information to users. Islandora's Islandora’s system is based on an understanding that the complexity of content-types and metadata standards, and the scarcity of metadata creation, management, and validation tools pose barriers to effective information management.
The following chapter will outline the role of descriptive metadata in the Islandora system. If you are using Islandora, it is presumed you have a strong understanding of metadata standards that you will be working with, and the role of descriptive metadata in organizing information assets.
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Islandora also preserves the use of Fedora's Fedora’s underlying administrative metadata (such as audit streams that indicate what has happened to an object) and relationship metadata (codified in the RELS-EXT streams of objects). Some Islandora Solution Packs also utilize the EXIFtool to extract technical metadata from objects and store it in a separate datastream. |
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Islandora utilizes Fedora's Fedora’s ability to represent Descriptive metadata in XML format via one or more Datastreams in an object. Fedora is written in such a way that any object may have multiple metadata Datastreams, which can store Metadata following any schema, such as MODS, Dublin Core, or QDC.
Metadata is added to an object in Islandora via an ingest form presented to users adding objects to the repositor, this ingest form produces an XML metadata datastream when the object is ingested. Each metadata stream will have a default DSID. Users fill out a form with fields corresponding to the metadata desired, and the relevant Datastream is created when the object in Fedora is created. The Datastreams that Islandora creates are defined in the Content Model Object that is affiliated with the Collection into which an item is being ingested. The Content Model prescribes, among other things, the DSID of a datastream containing metadata that can be viewed and edited via Islandora. Islandora's Islandora’s Solution Packs come with a Content Model which is ingested into your repository when the Solution Pack is installed, and which prescribes the type of metadata that will be collected on ingest, and in what Datastream that metadata will be stored. Users enter metadata via a Form that is defined in a Content Model. Solution Packs come with a set of forms pre-installed. These forms are based on our understanding of best practices, and represent a starting point for those new to the process of creating XML forms.
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Fedora requires that any object created in the system contain a default Dublin Core Stream. By extension, any object that is created in Islandora (and therefore in a Fedora repository) will have a default Dublin Core Datastream. However, Islandora's Islandora’s Solution Packs presume that users will often want to store an additional metadata stream outside of the default Dublin Core stream, in order to create richer descriptive metadata, and also to adhere to standards for metadata description of particular types of data and collections. For example, the MODS form that comes by default with any Solution Pack is designed to suit the most common cases for that solution pack.
This means that Islandora's Islandora’s Solution Pack Content Models come with a Datastream defined that allows for additional granularity and is customized to the needs of a particular data type or subject area. This also means that the Solution Packs come with a form that presents users with a richer metadata schema than Dublin Core. When metadata is created using the ingest form, an .xslt is called by the Content model. This .xslt file transforms the richer metadata schema into the default Dublin Core datastream, and stores both the richer XML based Descriptive Metadata and the Dublin Core Metadatain the object. In this way, Islandora preserves a common metadata stream that can be useful for searching and retrieving metadata objects across the repository, as well as a more granular metadata stream that describes the object as is most appropriate for the subject area or discipline to which the object refers. When a metadata field is updated through the interface, the .xslt is called to perform the transformation again, making sure that the Dublin Core datastream is kept consistent with the data in the richer Metadata Datastream.
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