Medley: An event-driven lightweight platform for service composition

Abstract

Distributed applications are evolving at a frantic pace, critically relying on each other to offer a host of new functionalities. The emergence of the service-oriented paradigm has made it possible to build complex applications as a set of self-contained and loosely coupled services that work altogether in concert. However, the traditional vision of Service-Oriented Architectures (SOA) based on web service specifications does not meet the trend of many major service providers. Instead, they promote microservices, a refinement of SOA focusing on lightweight communication mechanisms such as HTTP. Therefore, existing approaches for orchestrating the composition of various services become unusable in practice. In this paper, we introduce Medley, an event-driven lightweight platform for service composition. Medley is based on a domain-specific language for describing orchestration and a compiler that produces efficient code. We have used Medley to develop various compositions, involving a large number of existing services. Our evaluation shows that it scales both on a mainstream server and an embedded device while consuming a reasonable amount of resources.