Ensuring faultless communication behaviour in a commercial cloud

For many Cloud providers, the backbone of their system is a Cloud coordinator that exposes a portfolio of services to users. The goal of this work is to ensure that a Cloud coordinator interacts correctly with services and users according to a specification of their communication behaviour. To accomplish this goal, we employ session types to analyse the global and local communication patterns. A session type provides an appropriate level of abstraction for specifying message exchange patterns between participants. This work confirms the feasibility of applying session types to protocols used by a commercial Cloud provider. The protocols are developed in SessionJ, an extension of Java implementing session-based programming. We also highlight that the same techniques can be applied when Java is not the development environment by type checking runtime monitors, as in Scribble. Finally, we suggest how our methodology can be used to ensure the correctness of protocols for Cloud brokers, that integrate services exposed by multiple Cloud coordinators, each of whom must correctly cooperate with the Cloud broker.