A Typed Repository for OpenDLib

In this paper we advocate the benefits of introducing the notion of typing into Digital Library (DL) Repository Services. The OpenDLib Typed Repository Service allows DL designers to define typed repository sets, according to a type language T-DoMDL. Here a set becomes a container of digital objects sharing the same type-defined structure, i.e . properties, behaviors, and constraints. T-DoMDL types model a wide range of abstractions typically perceived in the Digital Library world, such as aggregation of digital objects, relations between digital objects, versioning of digital objects, and others. The immediate advantage is that DL designers can construct repository sets tailored to their application domains. Secondly, DL developers, while implementing software components handling DL objects, can count on data consistency and static type checking of their code w.r.t. the set types. Finally, objects conforming to a given type can be physically handled in order to optimize both access and disk space, e.g. videos can be stored in a datastream access fashion.