Operating system License Apache License 2.0 | Type Digital libraries Website projecthydra.org | |
Hydra is an open-source digital repository software product. Hydra's main components are Fedora Commons, Solr, Blacklight, and HydraHead (a Ruby on Rails plugin and gem, respectively). Each Hydra implementation is called a "Hydra head".
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History
The project was launched in 2009. The software was developed as a collaboration between Stanford University, the University of Virginia, the University of Hull, and Fedora Commons. The stated goal of the project was to "support the rapid development of multiple systems tailored to distinct needs, but powered by a common underlying repository."
Project governance
There are three governance bodies. The original collaborators, plus some newer members, form the Hydra Steering Group. That group oversees legal and administrative aspects of the project. A second body is made up of institutional partners. Over two dozen institutions are formal partners. The Hydra developers group is the third group and is made up of contributors to the Hydra software.
Use
Hydra is primarily used in libraries and digital repositories. It was originally developed to make use of metadata defined by the Library of Congress's Metadata Object Description Schema (MODS) standard. Hydra implements the Opinionated Metadata gem to create Domain-specific languages out of complex XML standards such as MODS. Other metadata standards, such as Dublin Core and Encoded Archival Description (EAD) are known to be employed in Hydra implementations.
Hydra allows storage of any type of digital files for the purposes of access and/or digital archiving. It is suited to both large and small collections, and is being used in some cases to allow faculty and researchers to self-deposit their own digital research materials.
The concept of Hydra "Heads" is unique to this repository software. Each head is a Ruby on Rails application that provides a user experience and set of specific functionalities to a certain user community using content and metadata (the body, with the content residing in Fedora and the metadata residing in Solr) that may be shared with other such heads. For example, a faculty member may use a certain Hydra head to crop, fine-tune, and submit a set of images that is relevant to their research. A casual user may use a different Hydra head to browse these images without the clutter of all the photo editing and submission capabilities. Finally, a librarian user may access yet another Hydra head to curate an online exhibit of research at their University, using the photographs submitted by the faculty member but employing a special curatorial interface.
Hydra has been modified to meet special needs, such as the development of GeoHydra at Stanford University.
Derivatives
Due to its extensive list of dependencies, Hydra is difficult for smaller institutions to implement. To make this software more feasible for such institutions, the Digital Public Library of America, Stanford University, and DuraSpace are partnering on a grant project from the Institute for Museum and Library Services called "Hydra-in-a-box". The goal of this project is to extend the Hydra codebase to "build, bundle, and promote a feature-rich, robust, flexible digital repository that is easy to install, configure, and maintain."