Implementation and Performance Evaluation of the WS-DAIR Interface for AMGA

WS-DAIR is the OGF proposed recommendation for access to relational database on the Grid. AMGA is one of first two reference implementations with which interoperability was tested for WS-DAIR standard ratification, in addition to OGSA-DAI. In this paper, we present a reference implementation model of the WS-DAIR interface for AMGA, and show some results of performance studies on the WS-DAIR interface with real Grid applications; WISDOM and Belle II. It provides very simplified WS-DAIR implementation model on data services and data resources, and supports most features of the existing AMGA implementation including replication, Grid accessibility, find-grained access control, hierarchical directory structure and heterogeneous backend database support. The performance study showed that the WS-DAIR access patterns and the message formats affect performance of the WS-DAIR service significantly. One issue found from the test results was that all the access patterns defined in the WS-DAIR specification may be inadequate to transfer large sized data in some applications. To deal with this issue, we have proposed to have considerations on streaming access pattern in the WS-DAIR specification, which can decrease response time and allow a WS-DAIR service to be more stabile when transferring large sized data.