Federated or multidatabase systems, built up from multiple autonomous database systems, require a basic level of interoperability among the component database systems. They must also provide a reasonable degree of functionality similar to that of modern database management systems, e.g., queries. Many years of research by other groups have gone into this area, but not many of the proposed solutions have been commercially implemented due to inherent complexities and relatively low probability of success. This paper discusses our interoperability solution that supports ad-hoc federations on a framework that adheres to technology standards. We hope to attract interest in ad-hoc federations which would be more responsive than rigid solutions. Through a standards-based solution, we hope to present an alternative approach that is practicable to implement. Our prototypes involve two key standards from the Object Management Group: the Common Object Request Broker Architecture (CORBA) and the Meta Object Facility (MOF). We also use the Extensible Markup Language (XML) for database metadata expression and interchange. We will show that our approach and framework are feasible based on the results of a prototyping effort.