@article {Distefano201722, title = {Marking dependency in non-Markovian stochastic Petri nets}, journal = {Performance Evaluation}, volume = {110}, year = {2017}, note = {cited By 0}, pages = {22-47}, publisher = {Elsevier B.V.}, abstract = {

Marking dependency is a powerful tool that allows different firing time distributions to be associated with a stochastic Petri net transition, depending on the marking. Through this feature, the modeler can easily and compactly represent advanced properties and behaviors of the system. While a semantics and specific solution techniques have been provided for generalized stochastic Petri nets thus covering homogeneous Markovian aspects, in the non-homogeneous/non-Markovian case marking dependency still needs to be investigated. To fill this gap, this paper provides a formalization of marking dependent semantics in non-Markovian stochastic Petri nets (NMSPNs) and a solution technique, based on phase type distributions and Kronecker algebra, able to deal with such a feature allowing both transient and steady-state analyses. To motivate the actual need of marking dependency in NMSPN modeling and to demonstrate the potential of such a feature as well as the validity of the proposed solution technique a case study on a multi-core CPU system with power management facilities is explored. {\textcopyright} 2017 Elsevier B.V.

}, keywords = {Algebra, energy management, Kronecker algebra, Marking dependency, Multi-core cpus, non-Markovian stochastic Petri nets, Petri nets, phase type distributions, Power management, Program processors, Random access storage, Semantics, Stochastic systems}, issn = {01665316}, doi = {10.1016/j.peva.2017.03.001}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016027299\&doi=10.1016\%2fj.peva.2017.03.001\&partnerID=40\&md5=a00a4d3147bd499b5f8879d3573b4670}, author = {Salvatore Distefano and Francesco Longo and Marco Scarpa} } @article {Longo2015280, title = {Dependability modeling of Software Defined Networking}, journal = {Computer Networks}, volume = {83}, year = {2015}, note = {cited By 6}, pages = {280-296}, publisher = {Elsevier}, abstract = {

Software Defined Networking (SDN) is a new network design paradigm that aims at simplifying the implementation of complex networking infrastructures by separating the forwarding functionalities (data plane) from the network logical control (control plane). Network devices are used only for forwarding, while decisions about where data is sent are taken by a logically centralized yet physically distributed component, i.e., the SDN controller. From a quality of service (QoS) point of view, an SDN controller is a complex system whose operation can be highly dependent on a variety of parameters, e.g., its degree of distribution, the corresponding topology, the number of network devices to control, and so on. Dependability aspects are particularly critical in this context. In this work, we present a new analytical modeling technique that allows us to represent an SDN controller whose components are organized in a hierarchical topology, focusing on reliability and availability aspects and overcoming issues and limitations of Markovian models. In particular, our approach allows to capture changes in the operating conditions (e.g., in the number of managed devices) still allowing to represent the underlying phenomena through generally distributed events. The dependability of a use case on a two-layer hierarchical SDN control plane is investigated through the proposed technique providing numerical results to demonstrate the feasibility of the approach. {\textcopyright} 2015 Elsevier B.V.

}, keywords = {Availability, Complex networks, Controllers, Degree of distributions, Distributed components, Electric network topology, Information dissemination, Markov processes, Networking infrastructure, Non-Markovian, Quality control, Quality of service, Random processes, Reliability, Reliability and availability, Software defined networking (SDN), Software reliability, Software-defined networkings, Stochastic models, Stochastic systems, Topology, Type expansions}, issn = {13891286}, doi = {10.1016/j.comnet.2015.03.018}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946489290\&doi=10.1016\%2fj.comnet.2015.03.018\&partnerID=40\&md5=b4f32c89d2b7b79fefcaf97082764960}, author = {Francesco Longo and Salvatore Distefano and Dario Bruneo and Marco Scarpa} } @article {Distefano2015629, title = {QoS Assessment of Mobile Crowdsensing Services}, journal = {Journal of Grid Computing}, volume = {13}, number = {4}, year = {2015}, note = {cited By 2}, pages = {629-650}, publisher = {Springer Netherlands}, abstract = {

The wide spreading of smart devices drives to develop distributed applications of increasing complexity, attracting efforts from both research and business communities. Recently, a new volunteer contribution paradigm based on participatory and opportunistic sensing is affirming in the Internet of Things scenario: Mobile Crowdsensing (MCS). A typical MCS application considers smart devices as contributing sensors able to produce geolocalized data about the physical environment, then collected by a remote application server for processing. The growing interest on MCS allows to think about its possible exploitation in commercial context. This calls for adequate methods able to support MCS service providers in design choices, implementing mechanisms for the quality of service (QoS) assessment while dealing with complex time-dependent phenomena and churning issues due to contributors that unpredictably join and leave the MCS system. In this paper, we propose an analytical modeling framework based on stochastic Petri nets to evaluate QoS metrics of a class of MCS services. This method requires to extend the Petri net formalism by specifying a marking dependency semantics for non-exponentially distributed transitions. The approach is then applied to an MCS application example deriving some QoS measures that can drive quantitative evaluation and characterization of the {\textquotedblleft}crowd{\textquotedblright} behavior. {\textcopyright} 2015, Springer Science+Business Media Dordrecht.

}, keywords = {crowdsensing, Digital storage, Distributed applications, Marking dependency, Non-Markovian, Performability, Petri nets, Quality of service, Quality of service (QoS) assessments, Quantitative evaluation, Semantics, Stochastic systems, Time dependent phenomena}, issn = {15707873}, doi = {10.1007/s10723-015-9338-7}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958155341\&doi=10.1007\%2fs10723-015-9338-7\&partnerID=40\&md5=3bd7e36a37ab06a3acabb37a21b90ab1}, author = {Salvatore Distefano and Francesco Longo and Marco Scarpa} } @article {Longo20152506, title = {Variable operating conditions in distributed systems: Modeling and evaluation}, journal = {Concurrency Computation Practice and Experience}, volume = {27}, number = {10}, year = {2015}, note = {cited By 1}, pages = {2506-2530}, publisher = {John Wiley and Sons Ltd}, abstract = {

SummaryPerformance and dependability evaluation plays a key role in the design of a broad range of systems, especially when strict requirements need to be met. This is particularly challenging in distributed contexts, where several components may interact among themselves by influencing each other. In this paper, we present an analytical method that allows the study of a class of systems where different operating conditions alternate by changing the stochastic behavior of the system components but still preserving the continuity of the performance and dependability quantities to investigate. The proposed solution technique, based on phase type distributions, Kronecker algebra, and ad-hoc fitting algorithms, can be applied for the analytical evaluation of a wide class of distributed systems. Examples are provided to show the usefulness and the applicability of the methodology, characterizing and investigating different performance and dependability aspects of three distributed computing systems, that is, a connection-oriented network, an Internet of Things application, and an Infrastructure-as-a-Service Cloud. Copyright {\textcopyright} 2014 John Wiley \& Sons, Ltd.

}, keywords = {Algebra, cloud computing, Conservative systems, Dependability, Distributed computer systems, Internet, Internet of Things, Kronecker algebra, Markov processes, Non-Markovian, Performance, phase type distributions, Stochastic systems}, issn = {15320626}, doi = {10.1002/cpe.3419}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84932604392\&partnerID=40\&md5=b8f197a50fa177e85f0c1ac2a93fe392}, author = {Francesco Longo and Dario Bruneo and Salvatore Distefano and Marco Scarpa} } @proceedings {Distefano2014255, title = {Non-Markovian modeling of a BladeCenter chassis midplane}, journal = {Proceedings of the 11th European Workshop on Computer Performance Engineering (EPEW)}, volume = {8721 Lecture Notes in Computer Science}, year = {2014}, note = {cited By 0; Conference of 11th European Workshop on Computer Performance Engineering, EPEW 2014 ; Conference Date: 11 September 2014 Through 12 September 2014; Conference Code:107431}, pages = {255-269}, publisher = {Springer Verlag}, address = {Florence, Italy, 11-12 September 2014}, abstract = {

In distributed contexts such as Cloud computing, the reliability and availability of the provided resources and services have to be assured in order to meet user requirements. At the infrastructure level, this specification is translated into tighter ones on the datacenter hosting physical resources. In this paper, starting from a real case study of the IBM BladeCenter, we provide a technique for the quantitative evaluation of datacenter infrastructure availability. The proposed technique allows one to take into account both aging phenomena and multiple operating conditions. In particular, one subsystem of the BladeCenter, the chassis midplane, is studied. Indeed, based on the stochastic characterization of the midplane reliability through statistic measurements, a model dealing with the non-exponential failure time distribution thus obtained is evaluated to demonstrate the suitability and the effectiveness of the proposed technique. {\textcopyright} 2014 Springer International Publishing.

}, keywords = {Aging phenomena, Chassis, Failure-time distribution, Non-Markovian modeling, Operating condition, Physical resources, Quantitative evaluation, Reliability and availability, Stochastic models, Stochastic systems, User requirements}, isbn = {9783319108841}, issn = {03029743}, doi = {10.1007/978-3-319-10885-8_18}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84906969232\&partnerID=40\&md5=6840d4a28b6ed80a602f4db06c10343b}, author = {Salvatore Distefano and Francesco Longo and Marco Scarpa and Kishor S. Trivedi} } @proceedings {Bruneo2010, title = {QoS assessment of WS-BPEL processes through non-Markovian stochastic Petri nets}, journal = {Proceedings of the 24th IEEE International Symposium on Parallel and Distributed Processing (IPDPS)}, year = {2010}, note = {cited By 11; Conference of 24th IEEE International Parallel and Distributed Processing Symposium, IPDPS 2010 ; Conference Date: 19 April 2010 Through 23 April 2010; Conference Code:80843}, publisher = {IEEE Computer Society}, address = {Atlanta, GA, United States, 19-23 April 2010}, abstract = {

Service Oriented Architecture (SOA) is the most important and effective software paradigm to design Internet-based services. Using the SOA technology, value-added services can be easily deployed as a combination of existing Web services. In this context, WS-BPEL language has become the SOA industrial standard. To allow services to be composed, business relationships between providers and consumers have to be adequately managed. This implies that a formal definition of Quality of Service (QoS) is agreed and that effective tools for its measurement have to be developed. However, the design ofQoS guaranteed composed Web services still requires several efforts due to the highly distributed nature ofsuch software applications. This work aims at proposing a methodology to evaluate Web service performance at the earliest design phase. We present a novel technique to translate WS-BPEL processes into non-Markovian stochastic Petri nets with the final goal to evaluate parameters such as service time distribution and service reliability. The obtained model can be numerically solved through automatic tools, allowing to investigate the service behavior under different operating conditions and thus helping software engineers to develop QoS-guaranteed software solutions. {\textcopyright} 2010 IEEE.

}, keywords = {Automatic tools, Business relationships, Computer software, Design, Design phase, Distributed parameter networks, Effective tool, Formal definition, Graph theory, Industrial standards, Information services, Internet-based services, Non-Markovian, Novel techniques, Operating condition, Petri nets, Quality of service, Service oriented architecture (SOA), Service reliability, Service time distribution, Software applications, Software engineers, Software paradigm, Software solution, Stochastic Petri Nets, Stochastic systems, Value added service, Web services, WS-BPEL}, isbn = {9781424464432}, doi = {10.1109/IPDPS.2010.5470391}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77954020712\&partnerID=40\&md5=70790f3d893defcf4e9c792d8b58c5da}, author = {Dario Bruneo and Salvatore Distefano and Francesco Longo and Marco Scarpa} }