International audienceWe study in this paper the cost of making a concurrent programming language reversible. More specifically, we take an abstract machine for a fragment of the Oz programming language and make it reversible. We show that the overhead of the reversible machine with respect to the original one in terms of space is at most linear in the number of execution steps. We also show that this bound is tight since some programs cannot be made reversible without storing a commensurate amount of information

We present a framework for statically detecting deadlocks in a concurrent object-oriented language with asynchronous method calls and cooperative scheduling of method activations. Since this language features recursion and dynamic resource creation, deadlock detection is extremely complex and state-of-the-art solutions either give imprecise answers or do not scale.In order to augment precision and scalability we propose a modular framework that allows several techniques to be combined. The basic component of the framework is a front-end inference algorithm that extracts abstract behavioural descriptions of methods, called contracts, which retain resource dependency information. This component is integrated with a number of possible different back-ends that analyse contracts and derive deadlock information. As a proof-of-concept, we discuss two such back-ends: (i) an evaluator that computes a fixpoint semantics and (ii) an evaluator using abstract model checking.

Complex networked applications are assembled by connecting software components distributed across multiple machines. Building and deploying such systems is a challenging problem which requires a significant amount of expertise: the system architect must ensure that all component dependencies are satisfied, avoid conflicting components, and add the right amount of component replicas to account for quality of service and fault-tolerance. In a cloud environment, one also needs to minimize the virtual resources provisioned upfront, to reduce the cost of operation. Once the full architecture is designed, it is necessary to correctly orchestrate the deployment phase, to ensure all components are started and connected in the right order.We present a toolchain that automates the assembly and deployment of such complex distributed applications. Given as input a high-level specification of the desired system, the set of available components together with their requirements, and the maximal amount of virtual resources to be committed, it synthesizes the full architecture of the system, placing components in an optimal manner using the minimal number of available machines, and automatically deploys the complete system in a cloud environment.

Abstract. We present a framework for statically detecting deadlocks in a concurrent object language with asynchronous invocations and operations for getting values and releasing the control. Our approach is based on the integration of two static analysis techniques: (i) an inference algorithm to extract abstract descriptions of methods in the form of behavioral types, called contracts, and (ii) an evaluator that computes a fixpoint semantics returning a finite state model of contracts. A potential deadlock is detected when a circular dependency is found in some state of the model. We discuss the theory and the prototype implementation of our framework. Our tool is validated on an industrial case study based on the Fredhopper Access Server (FAS) developed by SDL Fredhoppper. In particular we verify one of the core concurrent components of FAS to be deadlock-free.

Abstract. Concurrent reversibility has been studied in different areas, such as biological or dependable distributed systems. However, only "rigid" reversibility has been considered, allowing to go back to a past state and restart the exact same computation, possibly leading to divergence. In this paper, we present croll-π, a concurrent calculus featuring flexible reversibility, allowing the specification of alternatives to a computation to be used upon rollback. Alternatives in croll-π are attached to messages. We show the robustness of this mechanism by encoding more complex idioms for specifying flexible reversibility, and we illustrate the benefits of our approach by encoding a calculus of communicating transactions.

International audienceDynamic reconfiguration, i.e. changing at runtime the communication pattern of a program is challenging for most programs as it is generally impossible to ensure that such modifications won't disrupt current computations. In this paper, we propose a new approach for the integration of components in an object-oriented language that allows safe dynamic reconfiguration. Our approach is built upon futures and object-groups to which we add: i) output ports to represent variability points, ii) critical sections to control when updates of the software can be made and iii) hierarchy to model locations and distribution. These different notions work together to allow dynamic and safe update of a system. We illustrate our approach with a few examples

A Featured Transition System (FTS) is a formal behavioural model for software product lines, which represents the behaviour of all the products of an SPL in a single compact structure by associating transitions with features that condition their existence in products. In general, an FTS may contain featured transitions that are unreachable in any product (so called dead transitions) or, on the contrary, mandatorily present in all products for which their source state is reachable (so called false optional transitions), as well as states from which only for certain products progress is possible (so called hidden deadlocks). In this paper, we provide algorithms to analyse an FTS for such ambiguities and to transform an ambiguous FTS into an unambiguous FTS. The scope of our approach is twofold. First and foremost, an ambiguous model is typically undesired as it gives an unclear idea of the SPL. Second, an unambiguous FTS paves the way for efficient family-based model checking. We apply our approach to illustrative examples from the literature. CCS CONCEPTS• Software and its engineering → Specification languages; Formal methods; Software product lines.

A Software Product Line (SPL) is a family of similar programs generated from a common artifact base. A Multi SPL (MPL) is a set of interdependent SPLs that are typically managed and developed in a decentralized fashion. Delta-Oriented Programming (DOP) is a flexible and modular approach to implement SPLs. This paper presents new concepts that extend DOP to support the implementation of MPLs. These extensions aim to accommodate compositional analyses. They are presented by means of a core calculus for delta-oriented MPLs of Java programs. Suitability for MPL compositional analyses is demonstrated by compositional reuse of existing SPL analysis techniques.