A Compositional Semantics for Stochastic Reo Connectors

TL;DR

This paper introduces a stochastic, compositional semantics for Reo connectors that allows for QoS analysis by modeling delays and data rates, and translating to CTMCs for performance verification.

Contribution

It extends Reo automata with stochastic information and provides a translation to CTMCs, enabling automated QoS analysis of service compositions.

Findings

Stochastic Reo automata enable QoS-aware analysis.

Translation to CTMCs allows use of existing verification tools.

Facilitates end-to-end performance evaluation.

Abstract

In this paper we present a compositional semantics for the channel-based coordination language Reo which enables the analysis of quality of service (QoS) properties of service compositions. For this purpose, we annotate Reo channels with stochastic delay rates and explicitly model data-arrival rates at the boundary of a connector, to capture its interaction with the services that comprise its environment. We propose Stochastic Reo automata as an extension of Reo automata, in order to compositionally derive a QoS-aware semantics for Reo. We further present a translation of Stochastic Reo automata to Continuous-Time Markov Chains (CTMCs). This translation enables us to use third-party CTMC verification tools to do an end-to-end performance analysis of service compositions.