Making data findable, accessible, interoperable, and re-usable is an important but challenging goal. From an infrastructure perspective, repository technologies play a key role in supporting FAIR data principles. Fedora is a flexible, extensible, open source repository platform for managing, preserving, and providing access to digital content. Fedora is used in a wide variety of institutions including libraries, museums, archives, and government organizations. Fedora provides native linked data capabilities and a modular architecture based on well-documented APIs and ease of integration with existing applications. As both a project and a community, Fedora has been increasingly focused on research data management, making it well-suited to supporting FAIR data principles as a repository platform.
Fedora provides strong support for persistent identifiers, both by minting HTTP URIs for each resource and by allowing any number of additional identifiers to be associated with resources as RDF properties. Fedora also supports rich metadata in any schema that can be indexed and disseminated using a variety of protocols and services. As a linked data server, Fedora allows resources to be semantically linked both within the repository and on the broader web. Along with these and other features supporting research data management, the Fedora community has been actively participating in related initiatives, most notably the Research Data Alliance. Fedora representatives participate in a number of interest and working groups focused on requirements and interoperability for research data repository platforms. This participation allows the Fedora project to both influence and be influenced by an international group of Research Data Alliance stakeholders.
This paper will describe how Fedora supports FAIR data principles, both in terms of relevant features and community participation in related initiatives.
Fedora, the Flexible, Extensible, Digital Object Repository Architecture, is open source repository software that stores, preserves, and provides access to digital content.1 Fedora is built around the notion of flexibility; content can be modeled in a variety of different ways to support both simple and complex use cases. This flexibility is primarily based on linked data. Fedora uses Resource Description Framework (RDF) triples to create semantic links between resources, thereby allowing for data models unrestricted by traditional file and folder hierarchies. Along with this flexibility, Fedora supports millions of resources, both large and small, with configurable storage capabilities. But perhaps most importantly, Fedora is interoperable; it has been designed around a robust REST-API and an event-based messaging service that establish well-documented patterns for integrating Fedora with other applications and services to build a larger system (
Institutions adopt Fedora for a variety of reasons; as a flexible system Fedora can satisfy a number of use cases and requirements. However, most institutions turn to Fedora for its flexibility — while local use cases may start out relatively simple, they will inevitably grow more complex over time. Fedora supports this natural growth by accommodating more complex needs as they arrive. Just as importantly, Fedora is designed with durability in mind. Digital preservation is a complex topic, and Fedora does not seek to be an all-in-one digital preservation system, but it provides a number of features and integration patterns that support an overall digital preservation strategy (
The FAIR Data principles (
This section will look at each FAIR Data principle and its criteria in turn and describe how Fedora meets these criteria to support each principle.
Findability is defined by the following criteria:
(meta)data are assigned a globally unique and eternally persistent identifier.
data are described with rich metadata.
(meta)data are registered or indexed in a searchable resource.
metadata specify the data identifier.
As a resource-centric repository, Fedora assigns each resource, whether it be a metadata record or a file, a Uniform Resource Identifier (URI) that serves as a persistent identifier for that resource. Additional persistent identifiers may also be used; for example, a public-facing DOI could be registered and mapped to a Fedora resource, and that DOI could be stored as a metadata property on the resource in Fedora. This also means that metadata resources can be linked to the data they describe by storing and linking to the data identifier. Strong support for metadata is another key Fedora feature; any type of metadata based on any schema (including custom fields) may be used. This flexibility allows Fedora to be used across research domains. Fedora also provides strong support for indexing — metadata and data (in the case of text-based resources) can be indexed in any number of external indices; common use cases include Solr, Elasticsearch, and triples stores.
Accessibility is defined by the following criteria:
(meta)data are retrievable by their identifier using a standard protocol.
a. the protocol is open, free, and universally implementable.
b. the protocol allows for authentication and authorization.
metadata are accessible, even when the data are no longer available
Fedora provides a well-documented REST-API (
Interoperability is defined by the following criteria:
(meta)data use a formal, accessible, shared, and broadly applicable language for knowledge representation.
(meta)data use vocabularies that follow FAIR principles.
(meta)data include qualified references to other (meta)data.
In terms of metadata, Fedora has strong multilingual support. Any language may be used, and metadata can be stored in whatever format is most relevant (e.g. RDF, XML). Additionally Fedora’s native linked data support allows vocabularies to be used to enhance knowledge representation by referencing well-known terms rather than using custom values. For example, a subject field could reference a term in the Library of Conference Subject Headings vocabulary (
Reusability is defined by the following criteria:
meta(data) have a plurality of accurate and relevant attributes.
a. (meta)data are released with a clear and accessible usage license.
b. (meta)data are associated with their provenance.
c. (meta)data meet domain-relevant community standards.
Fedora’s rich metadata support allows for a wide variety of attributes, and RDF can be used to link resources to their licenses. These licenses could be stored as resources in the repository, or they could be external licenses such as those provided by Creative Commons.2 Fedora also has an optional Audit module that can be enabled to track the provenance of resources in the repository (including metadata). Once enabled, the module will create PREMIS metadata (
Fedora is more than software; it is also a community. The Fedora community participates in a variety of international efforts aimed at making progress on key project priorities. One such effort is the Next Generation Repositories report that was published by the Confederation of Open Access Repositories in 2017 (
The Fedora community is also involved in the Research Data Alliance,3 an international group focused on enabling research data sharing across borders and around the world. This group is obviously well-aligned with the FAIR data principles, and there are a number of interest and working groups within the RDA that are making progress toward these shared goals. One such group, the Research Data Repository Interoperability working group, recently published recommendations on a data packaging standard for increased interoperability between repository platforms on a machine-to-machine level (
Fedora is stewarded by DuraSpace,4 a not-for-profit organization funded primarily through membership. Institutions join DuraSpace and direct annual funding to support the project(s) of their choice. In 2017, 74 DuraSpace member institutions supported Fedora with $562,300 in funding (
The FAIR data principles represent an important community goal of making data Findable, Accessible, Interoperable, and Reusable. However, in order to put these principles into practice they must be broken down into criteria that can be supported by infrastructure. For each principle, Fedora has a set of features that satisfy these criteria and support the overall implementation of the FAIR Data principles. This can be demonstrated not only at the level of the software, but also in the Fedora community’s participation in related community efforts that further the goals of the FAIR data principles at a more strategic level. As community-supported, open source software, Fedora will continue to evolve to meet the needs of the research data management community as data is made more Findable, Accessible, Interoperable, and Reusable.