Safe compositional network sketches: formal framework

  • Authors:

  • Azer Bestavros;Assaf Kfoury;Andrei Lapets;Michael J. Ocean

  • Affiliations:

  • Boston University, Boston, MA, USA;Boston University, Boston, MA, USA;Boston University, Boston, MA, USA;Endicott College, Beverly, MA, USA

  • Venue:
  • Proceedings of the 13th ACM international conference on Hybrid systems: computation and control
  • Year:
  • 2010

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Abstract

NetSketch is a tool for the specification of constrained-flow applications and the certification of desirable safety properties imposed thereon. NetSketch assists system integrators in two types of activities: modeling and design. As a modeling tool, it enables the abstraction of an existing system while retaining sufficient information about it to carry out future analysis of safety properties. As a design tool, NetSketch enables the exploration of alternative safe designs as well as the identification of minimal requirements for outsourced subsystems. NetSketch embodies a lightweight formal verification philosophy, whereby the power (but not the heavy machinery) of a rigorous formalism is made accessible to users via a friendly interface. NetSketch does so by exposing tradeoffs between exactness of analysis and scalability, and by combining traditional whole-system analysis with a more flexible compositional analysis. The compositional analysis is based on a strongly-typed Domain-Specific Language (DSL) for describing and reasoning about constrained-flow networks at various levels of sketchiness along with invariants that need to be enforced thereupon. In this paper, we define the formal system underlying the operation of NetSketch, in particular the DSL behind NetSketch's user-interface when used in "sketch mode", and prove its soundness relative to appropriately-defined notions of validity. In a companion paper [7], we overview NetSketch, highlight its salient features, and illustrate how it could be used in applications that include: the management/shaping of traffic flows in a vehicular network (as a proxy for cyber-physical systems (CPS) applications) and a streaming media network (as a proxy for Internet applications).