The DCE Directory Service provides a dynamic white pages service, but DCE currently lacks a yellow pages service. A dynamic yellow pages service allows clients, at runtime, to find a required service by searching on service attributes. The ODP Trader provides such a service. We have implemented a trading service over DCE, which provides the basic ODP trading function and uses the operation signatures specified in the ODP Trader Standard. Our trading service consists of three functional components to provide, at runtime, the capabilities of defining and retrieving service types, searching and selecting required services, and locating addresses of service interfaces. In addition, a user agent component provides a simple, local interface for DCE users to access the trading service. The architecture of our implementation readily supports the extension and replacement of any of the above components without requiring the recompilation of user applications.