Evaluating Negotiation Cost for QoS-aware Service Composition

The value of commercial Service-Based Applications (SBAs) will depend not only on their functionality, but also on the value of their non-functional properties, known as QoS attributes, that are not tied to a specific functionality, but rather to its delivery features. QoS values may vary according to the provision strategies of providers as well as users’ requirements expressed as global constraints on the SBA QoS. Automatic negotiation is a viable approach to drive QoS-aware selection of services for SBAs, but its adoption may result computationally expensive due to the communication overhead among the involved negotiators, so limiting its application to real service-based scenarios. In this paper, an empirical evaluation of the impact of negotiation communication costs occurred when composing services to deliver a QoS-aware SBA is carried out, in order to estimate the advantages and disadvantages of negotiation in a market of services, and to identify negotiation parameters settings for which communication costs can be compensated by an increased probability for the negotiation to succeed.