Service composition has become commonplace nowadays, in large part due to the
increased complexity of software and supporting networks. Composition can be of
many types, for instance sequential, prioritising, non-deterministic. However,
a fundamental feature of the services to be composed consists in their
dependencies with respect to each other. In this paper we propose a theory of
service dependency, modelled around a dependency operator in the Action Systems
formalism. We analyze its properties, composition behaviour, and refinement
conditions with accompanying examples.Comment: In Proceedings Refine'15, arXiv:1606.0134
