Contracts play an essential role in the Service Oriented Computing, for which they need to be equiped with a sub-contract relation. We compare two possible formulations, one based on compliance and the other on the testing theory of De Nicola and Hennessy. We show that if the language of contracts is sufficiently expressive then the resulting subcontract relations are incomparable. However if w...

The advent of the SOA paradigm is expected to cause an increase in the number of available services. This increase can create a bottleneck for the location and, therefore, for the use of services that provide a particular value. In this paper, we propose a model for the effective location of services, and a prototype implementation of this model, with some features which make it applicable to h...