The OPen Network Data Access Protocol (OPeNDAP) is the leading network protocol for content-based access to online Earth science datasets. The Alexandria Digital Library (ADL) is the world's leading digital library for geospatial and georeferenced information. The functionalities of OPeNDAP and ADL are almost perfectly complementary and their combination will yield a unified set of network interfaces for query-based discovery, evaluation, verification, and retrieval of Earth science information across a distributed network of independent information providers.
The project integrates ADL and OPeNDAP by: (1) implementing a federated discovery system in ADL over an existing network of OPeNDAP servers; (2) adding Thematic Realtime Environmental Distributed Data Services (THREDDS) cataloging metadata (both in-line and third-party) to the OPeNDAP protocol; (3) developing a generic user interface, analogous to a desktop "open file" dialog, for ADL/OPeNDAP datasets; and (4) adding OPeNDAP functionality (content selection and projection operations) to ADL queries, so that the same query can apply to subsets of OPeNDAP datasets and to other library holdings (text, GIS layers, etc.).
The project forms an integrative bridge between digital libraries with their focus on query-based retrieval of heterogeneous content and Earth science data systems with their focus on functional access to (relatively) homogeneous content. The resulting coupling of query-based access to science data content with content-specific access to library holdings will enable a broad community of scientists and students to use the same query to compare the peer-reviewed knowledge in a library against the latest research results direct from the responsible researcher.
