Object Query Language - Enabling Service for Earth Observation Product Processing, Access and Dissemination

Abstract

Multi-mission product management systems have an uncontested primary focus on long term data preservation. However, sophisticated archive systems are incomplete if they provide only monosyllabic product identification and retrieval functions. The increasing diversity and amount of products, and an increasing complexity of applications require flexible and efficient query capabilities supporting spatio-temporal conditions, combination of related products and specific product metadata conditions and aggregations. This paper presents the Object Query Language (OQL) provided by the Product Library of the Data Information and Management System DIMS, the multi-mission ground segment infrastructure implemented and operated at DLR DFD. This comprehensive query language is the basis for an integrated inventory service supporting dynamic object-oriented metadata configuration, ad-hoc queries, event triggering, incremental query of huge result sets and full metadata inspection. OQL supports complex query conditions including object reference navigation and different spatio-temporal operators. The paper presents prominent examples of operational systems illustrating the advantages of OQL, enabling new possibilities for processing, access, subscription and dissemination of products.