QoS-Aware Adaptive Service Orchestrations

Service Oriented Computing enables distributed applications that orchestrate existing services exported by remote providers. This paradigm requires to explicitly handle possible changes that may affect the orchestration. They include changes that impact its functional behavior (e.g., services being retired by their providers), but also changes in the non-functional behavior of the orchestrated services (e.g., an increased execution time). In the past we developed DSOL: it combines a declarative language to model the orchestration with planning mechanisms to decide at run-time the best flow of actions. In this paper we extend DSOL to support QoS attributes and requirements. In particular, we combine the DSOL planning techniques with a linear optimizer to calculate the optimal plan w.r.t. the QoS requirements. Moreover, we leverage the DSOL ability to adapt the orchestration flow at run-time, to further optimize the QoS perceived by the end users depending on the actual situations encountered.