A Concept for Flexible Event-Driven Invocation of Distributed Service Compositions

Currently, flexible service compositions are invoked in a centralised manner by process execution engines. Although this approach is widely used for orchestrating Web services, it lacks scalability and incurs considerable overhead in network communication. This is especially disadvantageous in scenarios with embedded systems and other resource-constrained devices, mainly due to restrictions in network bandwidth or power supply. We present an application scenario to illustrate the drawbacks of centralised service invocation in these cases. Decentralised invocation mechanisms are a promising approach to overcome these problems. Based on the identification of service composition characteristics in distributed environments, we propose a decentralised mechanism using events and subscriptions. This mechanism can be employed for invoking distributed service compositions while offering improved scalability and efficiency. We conclude with discussing the advantages and restrictions of our solution compared to the centralised approach.