Service Combinators for Farming Virtual Machines

Management is one of the main expenses of running the server farms that implement enterprise services, and operator errors can be costly. Our goal is to develop type-safe programming mechanisms for combining and managing enterprise services, and we achieve this goal in the particular setting of farms of virtual machines. We assume each server is service-oriented, in the sense that the services it provides, and the external services it depends upon, are explicitly described in metadata. We describe the design, implementation, and formal semantics of a library of combinators whose types record and respect server metadata. We describe a series of programming examples run on our implementation, based on existing server code for order processing, a typical data centre workload.