Blazes: Coordination Analysis for Distributed Programs

Distributed consistency is perhaps the most discussed topic in distributed systems today. Coordination protocols can ensure consistency, but in practice they cause undesirable performance unless used judiciously. Scalable distributed architectures avoid coordination whenever possible, but under-coordinated systems can exhibit behavioral anomalies under fault, which are often extremely difficult to debug. This raises significant challenges for distributed system architects and developers. In this paper we present Blazes, a cross-platform program analysis framework that (a) identifies program locations that require coordination to ensure consistent executions, and (b) automatically synthesizes application-specific coordination code that can significantly outperform general-purpose techniques. We present two case studies, one using annotated programs in the Twitter Storm system, and another using the Bloom declarative language.Comment: Updated to include additional materials from the original technical report: derivation rules, output stream label

Concurrent constraints models of music interaction

International audienceIn this chapter we follow this "economy of means" way to present several vari- eties of CCP calculi, starting from a very basic one and building from it by adding new features. A fundamental one for music applications is the ability to represent temporal behavior. This can be introduced within the context of determinate (tcc, utcc) or non-determinate (ntcc) computation. For the determinate case, we show how the addition of a process abstraction feature (utcc) allows to model dynamic musical structures in a very simple way. In particular, we model a dynamic version of interactive scores ([ALL 07]). For the nondeterminate case, we use the possibility of defining many alternative computational paths to model an agent following different rhythmic patterns constructed from a given basic one. We then go on to consider a more "metrical" notion of time (rtcc) based on uniform ticks used by processes to define their time of execution in a more fine-grained way, or to cause preemption of other processes at more precisely defined points in time. We use these new "real-time" features to describe a simple model of a basic form of musical dissonances

Using formal methods to support testing

Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing

From RT-LOTOS to Time Petri Nets new foundations for a verification platform

The formal description technique RT-LOTOS has been selected as intermediate language to add formality to a real-time UML profile named TURTLE. For this sake, an RT-LOTOS verification platform has been developed for early detection of design errors in real-time system models. The paper discusses an extension of the platform by inclusion of verification tools developed for Time Petri Nets. The starting point is the definition of RT-LOTOS to TPN translation patterns. In particular, we introduce the concept of components embedding Time Petri Nets. The translation patterns are implemented in a prototype tool which takes as input an RT-LOTOS specification and outputs a TPN in the format admitted by the TINA tool. The efficiency of the proposed solution has been demonstrated on various case studies