SkyQuery: A WebService Approach to Federate Databases
  Traditional science searched for new objects and phenomena that led to discoveries. Tomorrow's science will combine together the large pool of information in scientific archives and make discoveries. Scienthists are currently keen to federate together the existing scientific databases. The major challenge in building a federation of these autonomous and heterogeneous databases is system integration. Ineffective integration will result in defunct federations and under utilized scientific data.   Astronomy, in particular, has many autonomous archives spread over the Internet. It is now seeking to federate these, with minimal effort, into a Virtual Observatory that will solve complex distributed computing tasks such as answering federated spatial join queries.   In this paper, we present SkyQuery, a successful prototype of an evolving federation of astronomy archives. It interoperates using the emerging Web services standard. We describe the SkyQuery architecture and show how it efficiently evaluates a probabilistic federated spatial join query. 
Tanu Malik, Alex S. Szalay, Tamas Budavari, Ani R. Thakar