www.elsevier.com/locate/entcs A Rewriting Semantics for a Software Architecture Description Language

Distributed and concurrent application invariably have coordination requirements. The design of those applications, composed by several (possibly distributed) components, has to consider coordination requirements comprising inter-component interaction styles, and intra-component concurrency and synchronization aspects. In our approach coordination aspects are treated in the software architecture level and can be specified in high-level contracts in CBabel ADL. A rewriting logic semantics for the software architecture description language CBabel is given, revisiting and extending previous work by some of the authors, which now includes a revision of the previous semantics and the addition of new features covering all the language. The CBabel tool is also presented. The CBabel tool is a prototype executable environment for CBabel, that implements the given CBabel’s rewriting logic semantics and allows the execution and verification of CBabel descriptions in the Maude system, an implementation of rewriting logic. In this way, software architectures describing complex applications can be formally verified regarding properties such as deadlock and synchronization consistency in the software architecture design phase of its life cycle

A Formal Semantics for a Quality of Service Contract Language

AbstractCurrent interests in the context of system development include non-functional aspects of an application and the quality of the service (QoS) it provides. In video on demand applications, for instance, properties such as delay, bandwidth and CPU utilization are monitored in order to identify if they are within acceptable limits. In our approach, non-functional requirements are described by contracts. A contract specifies acceptable variations on the availability of these properties and how service replacement can be negotiated to keep the QoS of the application within the acceptable limits. In this paper we give an operational semantics for QoS contracts and report its implementation in a prototype tool that allows us to execute and analyze QoS contracts. The QoS Tool, our prototype, transforms QoS contract descriptions into modular structural operational semantics (MSOS) specifications. MSOS specifications are executable and analyzable in the Maude MSOS Tool, which uses efficient rewriting to execute, search and model checking MSOS specifications. We exemplify how the QoS Tool can be used by analyzing a video on demand application against real data