Web Service Mediation Through Multi-level Views

The web Service MEDiator system (WSMED) provides general query capabilities over data accessible through web services by reading WSDL meta-data descriptions. Based on imported meta-data, the user can define views that extract data from the results of calls to web service operations. The views can be queried using SQL. The views are specified in terms of declarative queries that access different web service operations in different ways depending on what view attributes are known in a query. To enable efficient query execution over the views by automatic query transformations the user can provide semantic enrichments of the meta-data with key constraints. We evaluated the effectiveness of our approach over multi-level views of existing web services and show that the key constraint enrichments substantially improve query performance.