Over the last decade, ARIADNE has spent considerable effort on the development of standards and specifications for learning object repositories, with significant results. We consider the following standards and specifications as key technologies within the ARIADNE infrastructure.
In order to enable flexible access to content, we need rich descriptions: these are typically called metadata. We focus on the automatic generation and extraction of metadata as well as on so-called attention metadata that describe interactions with content, rather than just the content itself . For describing learning content, we mainly rely on IEEE LTSC LOM but we support other standards like Dublin Core (DC) and ISO/IEC MLR as well, by automatically transforming metadata from one format into another.
Frameworks for metadata harvesting (like OAI-PMH) enable harvesters to copy metadata from a repository and save this copy of the metadata locally . On top of this local copy, search services can be added to enable search in the metadata of the contents of the content providers. We typically do not copy content itself. Therefore, we do not have to deal with intellectual property rights and digital access management for the content. We do make available metadata about the content by harvesting metadata with the OAI-PMH protocol. ARIADNE asks providers to release their metadata under a CC license (CC-BY-SA-NC) to improve discoverability of learning content because all harvested metadata is exposed again in an OAI-PMH target where it can be harvested by other federations and repositories.
For publishing learning objects or their metadata into the ARIADNE infrastructure, we rely on the Simple Publishing Interface (SPI) specification. This model has been designed such that it is interoperable with:
- the “Simple Web-service Offering Repository Deposit (SWORD)” profile,
- the “Package Exchange Notification Services (PENS)” and
- the publishing specification that was developed in the ProLearn Network of Excellence.
With SPI, one can transfer digital educational resources from a variety of tools to the ARIADNE infrastructure.
The ARIADNE infrastructure provides a Simple Query Interface (SQI) on top of the repository which can be used to issue queries in various query languages such as PLQL. SQI provides interoperability between search applications and various learning object repositories and is designed to support many types of search technologies. Other specifications such as SRU/SRW, O.K.I OSIDs, etc. do exist. SQI serves as a gateway to them.