This article reports the efforts Alliance Digital Repository (ADR), a consortial digital repository service for the Colorado Alliance of Research Libraries (Alliance), to create a standard descriptive metadata policy for their repository records. Members in the Alliance included twelve separate libraries at nine different academies and institutions, public and private. The goal was to support each library's community standards while also ensuring interoperability. This would facilitate a central repository.
Needless to say the scope for a project like this, which is charged with accommodating a dozen libraries each with their own practices and metadata (not to mention unique data both from within and without the library), expands at a rate equal to thought itself.
The ADR eventually pared down the libraries' metadata they had to consider to:
- MARC
- MARC XML
- MODS
- DC
- Various extensions to these standard schemas
- ProQuest's Digital Dissertations XML-based metadata schema
As they note Fedora does not have a user-friendly interface for submission and searching built-in (like DSpace) so they chose Fez as a configurable front end, adding that other interfaces could be attached to Fedora as needed.
MODS was chosen as the "normalizing schema," the one all records would be converted to at a minimum no matter what metadata scheme they had upon ingestion. The report gives a really helpful list of reasons why, and I think it's interesting that #1 is the simple fact that Fez and MODS "are proven partners: The Fez system was already using MODS widely throughout the system as the primary means of describing objects." They give other factors: the right granularity, crosswalks to the popular data-sharing DC, and plain familiarity, but it's notable that the tool in this case (Fez) partly determined yet another tool.
ADR determined minimal metadata field requirements with DLF Aquifier, a Digital Library Federation initiative to help distributed library networks and content.
A very significant technical problem for ADR was validation of incoming records to make sure the minimum MODS metadata was there and was correct. They decided that XSD could both the valid structure for XML encoded MODS records and the correct data types as they had agreed upon. For instance a record would have not only the correct structure of metadata that a DTD might confirm, but also the correct data inside the metadata fields (for example the correct time, date, price, or URI format).
The problem derived from the fact that the packaged XSDs as used by Fez were not applicable for ADR's purposes, which meant the creation of new XSDs. Integration of new custom XSDs with Fez was poorly documented and ADR encountered functional bugs with Fez. A survey of Fez use revealed that no one else was trying to significantly modify Fez's XSD templates, and ADR's number of digital objects, each with unique metadata structures, was very large. Added to this was the need to crosswalk MODS to DC that required a whole new set XSDs for the DC metadata records.
ADR ended up authoring their own "document types" (MODS and DC XSD-validated metadata records) for use. That process is long and complex and ultimately did not provide the best treatment for heterogeneous objects (objects containing multiple genres of document types, like a web page) since Fez allowed such minimal description for a single document type. This forced them to store these objects as separate records.
What interests me with this report is not so much the specific technical problems and solutions they encountered (which are kind of torturous to read about) but that such huge obstacles can be created when the technical tools are insufficient to the task. On the one hand, MODS was easily selected and implemented for a number reasons, not least of which is that Fez worked smoothly with it. There are just a few paragraphs on it. On the other hand, entire collections of XSDs and the creation of a new conceptual entity (document types) is created largely because Fez has a poor capacity to deal with new or modified XSDs. Four pages detail this struggle, and it's unresolved at the conclusion of the article. I conclude that while the biggest struggles for digital curation and interoperability may be social, political, cultural and so on, the extent to which technical can grease the wheels is tremendous.








