The motivation for repository interoperation is to facilitate inter-organization and inter-disciplinary software sharing. A high quality repository for one domain may well contain software that is useful in other domains. For example, software from the mathematical software and parallel tools repositories will be useful across a number of application domains. Through interoperation maintainers of domain-specific repositories will be able to import selected software from other repositories and incorporate it into their own catalogs, perhaps with value-added information about how the software is used within their domain. Furthermore, different organization that maintain repositories within the same domain will be able to share software. The top-level NHSE directory will import software catalog records from all the participating domain-specific repositories in order to provide a single index to all the available HPCC software, and will thus increase the visibility of this software.
Software may be shared between interoperating repositories at two levels:
To carry out interoperation at the first level, the NHSE recommends the exchange of RIG BIDM catalog records using one of the Web bindings, as described in section 3.
A repository that interoperates at the second level would mirror the files for imported software and distribute this software to users itself, rather than having users retrieve the software from the owning repository. Advantages of the mirroring approach may be the provision of faster and more reliable service to users, and a single point of contact for users for administrative procedures such as licensing agreements. Problems with the mirroring approach are liability for enforcing legal restrictions and proper crediting of download and usage statistics to the originating repository.
The Repository in a Box (RIB) toolkit will facilitate interoperability by providing the following:
The enforcement of legal restrictions, including liability issues, is currently under study by the NHSE. Once these issues have been resolved, mechanisms for enforcing legal restrictions will be included as part of RIB.
The capabilities of assigning a location-independent name, such as a Uniform Resource Name (URN), to a software resource, and of resolving a name to one or more identical replicated copies, would greatly facilitate repository interoperation. There is also a need for authorized parties (e.g., author, librarian, reviewer) to be able to independently associate catalog information with a name. Future versions of RIB will incorporate mechanisms for assigning and resolving location-independent names of for associating metadata with such names.