The focus is moving from the problem of building data to the problem of accessing and efficient utilization of data fitting to the purpose of a user. A distributed technology and a standard of geodata and geoprocessing is needed to satisfy these needs. This paper suggests an implementation method of a standard interface defined by OpenGIS with CORBA which is a distributed object technology. A client can invoke Open API of the middleware implemented with CORBA through IIOP. CORBA server objects which provide a client with Open API is the essence of an interoperability. CORBA server objects wrap the data formats and access methods of different GIS engines, and translate the data formats of different data servers to a standard data format.