A Polynomial Translation of pi-calculus FCPs to Safe Petri Nets

We develop a polynomial translation from finite control pi-calculus processes to safe low-level Petri nets. To our knowledge, this is the first such translation. It is natural in that there is a close correspondence between the control flows, enjoys a bisimulation result, and is suitable for practical model checking.Comment: To appear in special issue on best papers of CONCUR'12 of Logical Methods in Computer Scienc

Static Safety for an Actor Dedicated Process Calculus by Abstract Interpretation

The actor model eases the definition of concurrent programs with non uniform behaviors. Static analysis of such a model was previously done in a data-flow oriented way, with type systems. This approach was based on constraint set resolution and was not able to deal with precise properties for communications of behaviors. We present here a new approach, control-flow oriented, based on the abstract interpretation framework, able to deal with communication of behaviors. Within our new analyses, we are able to verify most of the previous properties we observed as well as new ones, principally based on occurrence counting

Predicting global usages of resources endowed with local policies

The effective usages of computational resources are a primary concern of up-to-date distributed applications. In this paper, we present a methodology to reason about resource usages (acquisition, release, revision, ...), and therefore the proposed approach enables to predict bad usages of resources. Keeping in mind the interplay between local and global information occurring in the application-resource interactions, we model resources as entities with local policies and global properties governing the overall interactions. Formally, our model takes the shape of an extension of pi-calculus with primitives to manage resources. We develop a Control Flow Analysis computing a static approximation of process behaviour and therefore of the resource usages.Comment: In Proceedings FOCLASA 2011, arXiv:1107.584

A Novel Admission Control Model in Cloud Computing

With the rapid development of Cloud computing technologies and wide adopt of Cloud services and applications, QoS provisioning in Clouds becomes an important research topic. In this paper, we propose an admission control mechanism for Cloud computing. In particular we consider the high volume of simultaneous requests for Cloud services and develop admission control for aggregated traffic flows to address this challenge. By employ network calculus, we determine effective bandwidth for aggregate flow, which is used for making admission control decision. In order to improve network resource allocation while achieving Cloud service QoS, we investigate the relationship between effective bandwidth and equivalent capacity. We have also conducted extensive experiments to evaluate performance of the proposed admission control mechanism

A Language-based Approach to Distributed Resources

Modern computing paradigms for distributed applications advocate a strong control on shared resources available on demand in order to guarantee their correct usages. An illustrative example of such paradigms is Cloud Computing. In this dissertation, we study formal models for distributed applications, paying particular attention to resource usage analysis. Formal methods for specifying and analysing different aspects of resource management could play an important role for the widespread usages of distributed resources. They provide not only the theoretical framework to understand the stages underlying the design and implementation issues, but also the mathematically-based techniques for the specification and verifications of properties of such systems. In this dissertation, we introduce two models, called lambda clouds and G-Local pi calculus, which are extensions of the lambda calculus and pi calculus respectively. The lambda clouds is an extension of concurrent lambda calculus enriched with suitable mechanisms to express and enforce application-level security policies governing usages of resources available on demand in the clouds. We focus on the server side of cloud systems, by adopting a pro-active approach, where explicit security policies, which are expressed as a set of execution traces, regulate server's behaviour. By providing an abstract cloud semantics, we ensure that enforcing security policies embedded in cloud applications is sound. The G-Local pi calculus is built on top of the standard pi calculus by introducing new primitives to manage resources. Unlike the previous model, where resources are highly abstract, resources in this approach are modelled as stateful entities with local states and global policies. A high degree of loose coupling among applications and resources is achieved through the publish/subscribe model. Furthermore, we develop two static, language-based techniques, namely Control Flow Analysis (CFA) and Type and Effect Systems, to reason about resource usages and therefore able to predict \textit{bad} usages of resources. The CFA mainly focuses on reachability properties related to resource usages. It computes an over-approximation of resource usages of applications. As a result, if the approximation does not contain bad usages, then it guarantees that applications correctly use resources. The type and effect system provides a closer view of resource behaviour. Resource behaviour is extracted in the form of side effect of the type system. We exploit side effect to verify regular linear time properties, expressed by Linear Time Logic formulas, of resource usages

Actor Network Procedures as Psi-calculi for Security Ceremonies

The actor network procedures of Pavlovic and Meadows are a recent graphical formalism developed for describing security ceremonies and for reasoning about their security properties. The present work studies the relations of the actor network procedures (ANP) to the recent psi-calculi framework. Psi-calculi is a parametric formalism where calculi like spi- or applied-pi are found as instances. Psi-calculi are operational and largely non-graphical, but have strong foundation based on the theory of nominal sets and process algebras. One purpose of the present work is to give a semantics to ANP through psi-calculi. Another aim was to give a graphical language for a psi-calculus instance for security ceremonies. At the same time, this work provides more insight into the details of the ANPs formalization and the graphical representation.Comment: In Proceedings GraMSec 2014, arXiv:1404.163