New Directions in Digital Library Componentisation

The Open Digital Library project was created as an experimental framework to investigate component architectures for digital libraries. Its primary objectives were to determine if a model based on simplicity could be devised to form the basis for implementation of a wide range of typical digital library services. Initial results show that simplicity is possible, but there has been scepticism about the extension of OAI-PMH and concern over the increase in complexity as a result of breaking up historically monolithic systems into smaller components. Current work on the ODL project includes efforts to address these concerns and develop the model further to support issues faced in production environments, such as configuration, installation and redeployment. Based on feedback from digital library developers, the next generation of the ODL framework is based on an updated component architecture that is being developed independently of OAI-PMH, but influenced by emerging best practices such as XML encapsulation of records and Web Service-based interfaces. To address the increased complexity of componentised systems, the DL-in-a-Box project is documenting and packaging components for wider use and better understanding among developers. In addition, a parallel project is developing a visual environment for graphically composing digital library components into larger systems. In addition to the visual aspect, this project also is developing a generalised system for remote configuration of components, enabling a seamless shift from componentised to distributed componentised digital libraries. As a natural progression from current efforts, future work will involve the packaging of such componentised digital libraries into complete installable and configurable units. While all these efforts are experimental, it is hoped that the lessons learnt will contribute to the establishment of community-based standards for component-level interoperability. Ultimately, developers can be provided with a collection of right-sized solutions with the added advantage that their systems will be simple, open, extensible and reusable. Flexible digital libraries then can be built as networks of simple components, with more effort being expended on interesting services rather than basic infrastructure