A Logical Way to Negotiate Services

Service providers commonly provide only a fixed catalog of services to their clients. Both clients and service providers can benefit from service negotiation, in which a client makes a query for a specific service, and the provider counters with an offer. The query could include parameters that control the performance, reliability, and function of the service. However, a problem with service negotiation is that it can be expensive for a service provider to support. In this paper we define a formal negotiation policy language that enables automated service negotiation. In the model supported by the language, service providers can recursively obtain the services they need from sub-providers. The queries made by clients, and the offers returned from service providers, are expressed in quantifier-free first-order logic. Quantifier elimination is used to transform constraints between providers and sub-providers. The pattern of interaction between clients and service providers is defined in process algebra. We show a correctness property of our language: if sub-providers respond positively to queries, then so does the provider itself.