Rome Wasn't Digitized in a Day - Council on Library and Information ...

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representations beyond the borders of host<strong>in</strong>g repositories,” Tarrant et al. decided to see if it could be
used to support a new level of cross-repository services. OAI-ORE was orig<strong>in</strong>ally developed with the
idea of creat<strong>in</strong>g descriptions of aggregations of digital objects (e.g., <strong>in</strong>dividual PDFs that are chapters
of a book) and the relationships between them that could be used by any digital repository platform.
The OAI-ORE specification uses the concepts of Aggregations and Aggregated Resources, where an
Aggregation represents a set of Aggregated Resources, with each resource and the Aggregation itself
be<strong>in</strong>g represented by URIs. Tarrant et al. expla<strong>in</strong>ed that <strong>in</strong> a sample OAI-ORE implementation the
highest level Aggregation could be the repository itself; it could conta<strong>in</strong> various Aggregated Resources
(e.g., research publications), each of which <strong>in</strong> turn could conta<strong>in</strong> its own Aggregated Resources (e.g.
an associated dataset, an image, etc.). Resource Maps are used to describe <strong>in</strong>dividual Aggregations
(and can l<strong>in</strong>k to only one aggregation), and each Resource Map must have a unique URI but can also
make use of various namespaces and metadata schemas. OAI-ORE models can be represented either <strong>in</strong>
RDF XML or the Atom syndication format.
The solution Tarrant et al. (2009) implemented made use of OAI-ORE with various extensions (e.g.,
writ<strong>in</strong>g export and import plug-<strong>in</strong>s, creat<strong>in</strong>g an <strong>in</strong>dividual application to create resource maps from
digital objects stored <strong>in</strong> Fedora us<strong>in</strong>g RDFLib) 710 to replicate all digital objects <strong>in</strong> two different
repositories (<strong>in</strong>clud<strong>in</strong>g their metadata and object history data) and enabled them to execute a lossless
transfer of all digital objects between a Fedora and EPr<strong>in</strong>ts archive and vice versa. 711 By represent<strong>in</strong>g
repository content through OAI-ORE Resource Maps, they proposed that many different digital
repository platforms could then be used to provide access to the same content, which would enable an
important “transformation from repositories-as-software to a services-based conception.” OAI-ORE
also specifies a number of different import and export <strong>in</strong>terfaces that support the exchange and reuse of
digital objects, and Tarrant et al. (2009) believed that this feature could greatly aid <strong>in</strong> digital
preservation by enabl<strong>in</strong>g simpler migration of objects between platforms:
OAI-ORE provides another tool to help repository managers tackle the problem of long-term
preservation, provid<strong>in</strong>g a simple model and protocol for express<strong>in</strong>g objects so they can be
exchanged and re-used. In future we hope to see OAI-ORE be<strong>in</strong>g used at the lowest level
with<strong>in</strong> a repository, the storage layer. B<strong>in</strong>d<strong>in</strong>g objects <strong>in</strong> this manner would allow the
construction of a layered repository where the core is the storage and b<strong>in</strong>d<strong>in</strong>g and all other
software and services sit on top of this layer (Tarrant et al. 2009).
The use of OAI-ORE illustrates one data model that might be used by different digital classics or
digital humanities repositories that wish to support the not just the reuse of their objects <strong>in</strong> various
digital applications but also their replication across different digital repository platforms.
Johns Hopk<strong>in</strong>s University used OAI-ORE to represent various data aggregations <strong>in</strong> an astronomical
data case study. Their data model <strong>in</strong>cluded Resource Maps that represented Aggregations that
conta<strong>in</strong>ed multiple digital objects as well as objects beyond the <strong>in</strong>dividual Aggregation that were stored
<strong>in</strong> a large number of repositories. Choudhury argued that <strong>in</strong>dividual repositories could never be
expected to <strong>in</strong>clude this level of data. “At some fundamental level, OAI-ORE acknowledges the
realization that repositories are not an end,” Choudhury remarked, “but rather a means to participate <strong>in</strong>
710 A Python library for work<strong>in</strong>g with RDF, available at (http://rdflib.net/).
711 Their approach also won the 2008 Common Repositories Interface Group (CRIG) challenge.