  We propose a framework for expressing and analyzing the Quality of Service
(QoS) of message-passing systems using a choreographic model that consists of
g-choreographies and Communicating Finite State machines (CFSMs). The following
are our three main contributions: (I) an extension of CFSMs with non-functional
contracts to specify quantitative constraints of local computations, (II) a
dynamic temporal logic capable of expressing QoS, properties of systems
relative to the g-choreography that specifies the communication protocol, (III)
the semi-decidability of our logic which enables a bounded model-checking
approach to verify QoS property of communicating systems.
