Scenarios-Based Testing of Systems with Distributed Ports

Current distributed systems are usually composed of several distributed components that communicate through specific ports. When testing these systems we separately observe sequences of inputs and outputs at each port rather than a global sequence and potentially cannot reconstruct the global sequence that occurred. In this paper we concentrate on the problem of formally testing systems with distributed components that, in general, have independent behaviors but that at certain points of time synchronization can occur. These situations appear very often in large real systems that regularly go through maintenance and/or update operations. If we represent the specification of the global system by using a state-based notation, we say that a scenario is any sequence of events that happens between two of these operations; we encode these special operations by marking some of the states of the specification. In order to assess the appropriateness of our new framework, we show that it represents a conservative extension of previous implementation relations defined in the context of the distributed test architecture: If we consider that all the states are marked then we simply obtain ioco (the classical relation for single-port systems) while if no state is marked then we obtain dioco (our previous relation for multi-port systems).