Optimising mediator queries to distributed engineering systems

Data and computations of a CAD system have been wrapped by a mediator system using CORBA's IIOP Protocol. This allows ad hoc declarative mediator queries to be translated into optimised execution plans sending dynamic IIOP messages to a CAD server. Queries may call computational methods provided only by the CAD system. Dynamic query re-optimisation taking into account what data is currently materialised in the mediator substantially improves the performance compared to static optimisation, despite the added optimisation time. The approach provides both increased flexibility and efficiency compared to the conventional navigational use of CORBA-based CAD interfaces. Furthermore, CAD independences is provided since transparent queries and views can be defined over different CAD systems.