Prof. David Walker

"A Killer App for Programming Languages Researchers"

(Vortrag im Rahmen der "Distinguished Lecture Series" des "Max Planck Instituts für Software-Systeme")

Modern computer networks perform a bewildering array of tasks, from routing and traffic monitoring, to access control and server load balancing. Moreover, historically, managing these networks has been hideously complicated and error-prone, due to a heterogeneous mix of devices (e.g., routers, switches, firewalls, and middleboxes) and their ad hoc, closed and proprietary configuration interfaces. Software-Defined Networking (SDN) is poised to change this state of affairs by offering a clean, simple and open interface between network devices and the software that controls them. In particular, many commercial switches now support the OpenFlow protocol, and a number of campus, data-center, and backbone networks have deployed the new technology.

However, while SDN makes it possible to program the network, it does not make it easy: The first generation of SDN controllers offered application developers the "assembly language" of network programming platforms. To reach SDN's full potential, research in programming languages and compilers is desperately needed. In this talk, I discuss our work to date in this area, which revolves around the design of a language, compiler and run-time system for SDN programming. The language, called Frenetic, allows programmers to work declaratively, specifying the behavior of a network at a high level of abstraction. The compiler and run-time system take care of the tedious details of compiling and implementing these high-level policies using the OpenFlow protocol.

A key strength of the Frenetic design is its support for modular programming: Complex network applications can be decomposed in to logical subcomponents --- an access control policy, a load balancer, a traffic monitor --- and coded independently. Frenetic's rich combinator library makes it possible to stitch such components back together to form a fully functioning whole. Frenetic also contains carefully designed operators that help users transition from one global, high-level network policy to the next while preserving key network invariants. Overall, Frenetic's abstractions make it dramatically easier for programmers to write and reason about SDN applications.