The paper describes an architectural model supporting the development of a particular type of application with the trading of intangible goods. To control the coordination of trading partners, a coordination mechanism is presented based on an event oriented workflow engine. This work intends to give some support to the idea that workflow technology can be suitable for this type of application. A possible application case is illustrated. To describe this business process, basic constructs of a process definition language were proposed. The paper ends with some considerations about the implementation of the coordinating workflow engine, and about the distribution in the Internet of the infrastructure used on the implementation.