The Servers of Serverless Computing: A Formal Revisitation of Functions as a Service

Authors Saverio Giallorenzo , Ivan Lanese , Fabrizio Montesi , Davide Sangiorgi , Stefano Pio Zingaro

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Saverio Giallorenzo
  • University of Southern Denmark, Odense, Denmark (former)
  • University of Bologna/INRIA, Italy (current)
Ivan Lanese
  • University of Bologna/INRIA, Italy
Fabrizio Montesi
  • University of Southern Denmark, Odense, Denmark
Davide Sangiorgi
  • University of Bologna/INRIA, Italy
Stefano Pio Zingaro
  • University of Bologna/INRIA, Italy

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Saverio Giallorenzo, Ivan Lanese, Fabrizio Montesi, Davide Sangiorgi, and Stefano Pio Zingaro. The Servers of Serverless Computing: A Formal Revisitation of Functions as a Service. In Recent Developments in the Design and Implementation of Programming Languages. Open Access Series in Informatics (OASIcs), Volume 86, pp. 5:1-5:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Serverless computing is a paradigm for programming cloud applications in terms of stateless functions, executed and scaled in proportion to inbound requests. Here, we revisit SKC, a calculus capturing the essential features of serverless programming. By exploring the design space of the language, we refined the integration between the fundamental features of the two calculi that inspire SKC: the λ- and the π-calculus. That investigation led us to a revised syntax and semantics, which support an increase in the expressiveness of the language. In particular, now function names are first-class citizens and can be passed around. To illustrate the new features, we present step-by-step examples and two non-trivial use cases from artificial intelligence, which model, respectively, a perceptron and an image tagging system into compositions of serverless functions. We also illustrate how SKC supports reasoning on serverless implementations, i.e., the underlying network of communicating, concurrent, and mobile processes which execute serverless functions in the cloud. To that aim, we show an encoding from SKC to the asynchronous π-calculus and prove it correct in terms of an operational correspondence. Dedicated to Maurizio Gabbrielli, on his 60th birthday (... rob da mët ! )

Subject Classification

ACM Subject Classification
  • Computer systems organization → Cloud computing
  • Theory of computation → Concurrency
  • Serverless computing
  • Process calculi
  • Pi-calculus


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