Analysis and Evaluation of Service Oriented Architectures for Digital Libraries

The Service Oriented Architecture (SOA) that underlies the Web Services paradigm of computing is widely regarded as the future of distributed computing. The applicability of such an architecture for digital library systems is still uncertain, as evidenced by the fact that virtually none of the large open source projects (e.g., Greenstone, EPrints, DSpace) have adopted it for internal component structuring. In contrast, the Open Archives Initiative (OAI) has received much support in the DL community for its Protocol for Metadata Harvesting, one that in principle falls within the scope of SOA. As a natural extension, the Open Digital Library project carried the principles of the OAI forward into a set of experimental derived and related protocols to create a testbed for component-based digital library experiments. This paper discusses a series of experiments with these components to confirm that SOA and a service-oriented component architecture is indeed applicable to building flexible, effective and efficient digital library systems, by evaluating issues of simplicity and understandability, reusability, extensibility and performance.