Component simulation-based substitutivity managing QoS and composition issues

Several scientific bottlenecks have been identified in existing component-based approaches. Among them, we focus on the identification of a relevant abstraction for the component expression and verification of properties like substitutivity: when is it possible to formally accept or reject the substitution of a component in a composition? This paper suggests integer weighted automata to tackle this problem when considering a new factor — Quality of Service (QoS). Four notions of simulation-based substitutivity managing QoS aspects are proposed, and related complexity issues on integer weighted automata are investigated. Furthermore, the paper defines composition operators: sequential, strict-sequential and parallel compositions, bringing path costs into the analysis. New results on the compatibility of proposed substitutivity notions w.r.t. sequential and parallel composition operators are established.