Synchronising Service Compositions in Dynamic Ad Hoc Environments

Abstract

Service compositions in dynamic ad hoc environments face frequent changes in the network and service topology. Late service binding is a way to adapt to runtime changes but requires additional communication over error-prone and energy-constrained networks. In particular, synchronising parallel service flows relies on steady message exchange when mutually unknown service providers have to agree on a common merge node. Binding the merge node early through a single entity reduces the need for coordination. However, it compromises flexibility and may nonetheless increase communication as the decision entity has only partial view of the system. This paper proposes a multi-party late binding protocol as a solution for flexible, communication-aware service composition in dynamic ad hoc environments. The protocol integrates the discovery of unknown synchronisation partners with the exchange of binding suggestions to reduce communication. We embed this protocol in our model for opportunistic service composition and evaluate it against an early binding approach. Simulation results show that while being overall equally successful, late service binding outperforms early binding with respect to communication overhead and response time.