Distributed Coordinated Adaptation of Cloud-based Applications

Steering modern Internet applications in the Cloud, given a set of functional and non-functional requirements, is a complex task. System maintainers need to have a holistic view of the application; they need to understand the intricate horizontal and vertical dependencies that exist between the infrastructure, platform, and software constituents. In this paper we advocate that MAPE control loops can help, and we focus on coordination of multiple adaptation actions. To this end we have developed a simple language for describing the adaptation capabilities of an Internet application. We then use this description to understand the dependencies that exist among the different adaptations we want to execute. Finally, we provide a distributed framework that, given a complex adaptation plan, helps our actuators collaborate in a decentralized fashion. We have validated our approach on an on-line auction application, deployed onto a mix of physical servers and Amazon EC2 virtual machines.