Stochastic Petri Net Package Research Articles

SPN-Based Performance Analysis of Multiple Users’ Behaviors for SNS

With the rapid development of various applications of Information Technology, big data are increasingly generated by social network services (SNS) nowadays. The designers and providers of SNS distribute different client applications for PC, Mobile phone, IPTV etc., so that users can obtain related service via mobile or traditional Internet. Good scalability and considerably short time delay are important indices for evaluating social network systems. As a result, investigating and mining the principle of users’ behaviors is an important issue which can guide service providers to establish optimal systems with SNS. On the basis of analyzing the characteristics of social network system, this paper constructed a Stochastic Petri Net (SPN) model for describing the behaviors of three users for SNS. Moreover, the scalability of users’ behaviors of SNS was studied by extending the SPN model of three users to the one of four users. Furthermore, average time delay was chosen as the performance index to evaluate the performance of these two constructed SPN models with Stochastic Petri Net Package (SPNP) 6.0. For different parameters of number of connections, traffic load and buffer size, various trends and numerical results are derived thereby. The methodology of modeling and simulation in this paper can be further used to study the performance of SNS.

Analyzing stochastic reward nets by model checking and parallel simulation

This paper deals with Stochastic Reward Nets (SRN), which are a powerful extension of Generalized Stochastic Petri Nets (GSPN). SRN have proved their usefulness in modelling and analysis of performance, availability and reliability of complex timed systems. SRN are supported by special-case tools like the Stochastic Petri Net Package (SPNP) which enables both analytic (based on Markov Reward Models) and simulative studies. The work described in this paper argues that there is still a gap in SRN analysis concerning functional correctness and non-deterministic property checking. Toward this a novel approach is proposed, which is based on two developed tools. First a formal reduction of SRN onto the Timed Automata (TA) of the popular Uppaal toolbox was defined and implemented. The Uppaal reduction enables a more complete investigation of SRN models, not allowed by existing SRN tools. However, the practical use of Uppaal forbids to study the performance of large models. Then, an SRN kernel, inspired by the carried formal Uppaal modelling and reasoning, was achieved in Java using the Theatre actor system. The realization supports the parallel simulation of scalable models. The paper applies the developed tools to a realistic grid-computing model and reports some experimental results, together with good execution performance (speedup) when using a scalable version of the grid model on a shared memory multi-core machine.

Stochastic Petri Net-based performance evaluation of hybrid traffic for social networks system

A social network is a social structure made up of a set of social actors (such as individuals or organizations) and a set of the dyadic ties between these actors. By contrast, for the fixed time duration the size of digital video would be much bigger than that of digital sound. Consequently, providers of social network services can offer real-time chatting among users which could offer satisfactory experiences for users. As one of the most popular content-based social network services (SNS), chatting service plays an important role in current big data era. Also average data packets׳ transmission via networks is another significant traffic. So how to offer satisfactory Quality of Service (QoS) for users is the key problem which will be solved for SNS provider. For real time communication among users, end-to-end time delay seems to be critical in user׳s experience. Therefore modeling and evaluating social network systems is an important and urgent issue which offers quantitative basis of SNS with high quality for users. For social network system, the scalability and robust are important for both service provider and users under the circumstance of a large number of users. On the basis of performance evaluation of social network system of one user case, we construct the SPN model and conduct numerical analysis to discover and report the performance with the addition of users. By taking hybrid traffic containing voice and data into account, this paper constructed a Stochastic Petri Net (SPN) model for data and ON/OFF voice traffic for social network system. Then, average time delay of the system was analyzed and model-based simulation is conducted with Stochastic Petri Net Package (SPNP) 6.0. Furthermore, for different parameters of burst rate, idle rate, number of data packets, traffic load and buffer size, variation trends on average time delay are derived thereby. On the basis of the work in this paper, further research on heterogeneous objects of social network systems can be carried on.

Dynamic Scalable Stochastic Petri Net: A Novel Model for Designing and Analysis of Resource Scheduling in Cloud Computing

Performance evaluation of cloud computing systems studies the relationships among system configuration, system load, and performance indicators. However, such evaluation is not feasible by dint of measurement methods or simulation methods, due to the properties of cloud computing, such as large scale, diversity, and dynamics. To overcome those challenges, we present a novel Dynamic Scalable Stochastic Petri Net (DSSPN) to model and analyze the performance of cloud computing systems. DSSPN can not only clearly depict system dynamic behaviors in an intuitive and efficient way but also easily discover performance deficiencies and bottlenecks of systems. In this study, we further elaborate some properties of DSSPN. In addition, we improve fair scheduling taking into consideration job diversity and resource heterogeneity. To validate the improved algorithm and the applicability of DSSPN, we conduct extensive experiments through Stochastic Petri Net Package (SPNP). The performance results show that the improved algorithm is better than fair scheduling in some key performance indicators, such as average throughput, response time, and average completion time.

논스톱 포워딩 기능을 지원하는 네트워크 시스템에 대한 다중화 모형의 가용도 분석

In this paper, we analyse the effect of redundancy types and non-stop forwarding scheme on network service availability. We use stochastic reward net models as enabling modeling approach for the analytical evaluation. We first design stochastic reward nets for redundancy models with or without non-stop forwarding and then evaluate their availability using Stochastic Petri Net Package.

SPN-Based Performance Evaluation for ON-OFF Voice Traffic System

By taking voice traffic system as study object, mathematical modeling methodology was used to investigate different parameters’ variations on system’s performance. Firstly, on the basis of analyzing the characteristics of voice traffic, this paper constructed a Stochastic Petri Net (SPN) model for ON-OFF voice traffic system. Furthermore, average time delay of the system was analyzed and model-based simulation was conducted with Stochastic Petri Net Package (SPNP) 6.0. For different parameters of ON to OFF rate and user’s voice connections, variation trends of number of user’s connections and ON to OFF rate are derived thereby. The methodology of modeling and simulation in this paper can be further used to analyze the performance of multimedia hybrid traffic system.

Performance analysis of finite-source retrial queues with nonreliable heterogenous servers

Retrial queueing models are often used for the performance and reliability modeling of computer systems and communication networks. The reason is that the return of customers plays a special role in many of these systems as well as in other practical applications, and it has a nonneglectable negative effect on the performance measures. For some applications of retrial queues, see, for example, [1–4], and for some fundamental results on finite-source retrial queueing systems, refer to [5–9]. Usually, the components of computer systems are subject to random breakdowns, which has a substantial influence on the performance measures, so it is of practical importance to investigate nonreliable retrial queueing systems, too. Nonreliable, infinite-source retrial queues were studied in [10–12] and finite-source retrial queues with a single nonreliable server were studied in [13]. The purpose of this paper is to generalize the model of [9, 13] and to give the main stationary performance measures of the nonreliable multiserver model described in the next section. Furthermore, our aim is to illustrate graphically the effect of the nonreliability of the servers on the steady-state systems’s measures. Because of the fact that the state space of the Markov chain described is very large, it is difficult to calculate the system measures in the traditional way of solving the system of steady-state equations. To simplify this procedure, we used the software tool MOSEL (Modeling, Specification, and Evaluation Language) (see [14]) to formulate the model and to obtain the performance measures. With the help of MOSEL, we can use various performance tools (such as SPNP — Stochastic Petri Net Package) to get these characteristics. The results of the tool can graphically be displayed using IGL (Intermediate Graphical Language), which is a part of MOSEL. The organization of the paper is as follows. Section 2 contains an accurate description of the investigated retrial queueing model and the derivation of the main steady-state performance measures. Section 3 is devoted to the validation of the results of the tool and some graphically displayed numerical results. The paper ends with Comments and Conclusions.

Design and Performance Analysis of a New Soft Handoff Scheme for CDMA Cellular Systems

In this paper, a new soft handoff scheme for CDMA cellular systems is proposed and investigated. It is pointed out that some handoff calls unnecessarily occupy multiple channels with little contribution to the performance of handoffs in IS95/CDMA2000-based handoff schemes or systems. To alleviate performance degradation due to channel resource shortage during soft handoff, a new concept of channel convertible set (CCS), which contains several types of handoff calls that unnecessarily occupy extra channels by considering the relative mobility of the calls in the handoff area is introduced. A new scheme that reallocates those extra channels in the CCS to new handoff calls when there is no available free channel in the system is proposed. Furthermore, according to the variation of the CCS, the proposed scheme dynamically adjusts the number of guard channels reserved exclusively for handoff. Then, the feasibility and implementation issues of the proposed scheme are discussed. To evaluate and compare performance indexes of different soft handoff schemes, continuous-time Markov chain models are constructed. Automated generation and solution of the underlying Markov chains are facilitated by stochastic reward net models, which are specified and solved by stochastic Petri net package. Numerical results show that this scheme can significantly decrease both the number of dropped handoff calls and the number of blocked calls without degrading the quality of communication service and the soft handoff process

Modeling and performance analysis of dispatching policies in dispatcher-based web server cluster

There are two kinds of dispatching policies in content-aware web server cluster: segregation dispatching policy and mixture dispatching policy. Traditional scheduling algorithms all adopt mixture dispatching policy. They do not consider that dynamic requests' serving has the tendency to slow down static requests' serving, and the different requests have different resource demands, so they can not use cluster's resource reasonably and effectively. This paper uses stochastic reward net (SRN) to model and analyze the two dispatching policies, and uses stochastic Petri net package (SPNP) to simulate the models. The simulation results and practical tests both show that segregation dispatching policy is better than mixture dispatching policy. The principle of segregation dispatching. policy can guide us to design efficient scheduling algorithm.

Achieving high availability and performance computing with an HA-OSCAR cluster

High availability (HA) computing has long gained much attention in enterprise and mission critical systems. HA goals are to maximize the uptime, thus undoubtedly complementing high-performance computing (HPC) objectives. HA-OSCAR is a project that aims to improve HA in commercial-off-the-shelf (COTS)-based HPC environments. In this paper, we introduce a multi-head HPC cluster architecture. Server redundancy is an initial key aspect aiming toward downtime reduction. Two HA-OSCAR types, active–standby and active–active, are studied. We evaluate system dependability for given two models. Stochastic Reward Nets (SRN) are used to model the system availability. We describe our SRN modeling using Stochastic Petri Net Package, and compute several interesting results that characterize HA-OSCAR availability.

A proactive approach towards always-on availability in broadband cable networks

In this paper, we propose a high availability design of a Cable Modem Termination System (CMTS) clusters system based on the software rejuvenation technique. This proactive system maintenance technique is aimed to reduce system outages and the associated downtime cost due to the ‘software aging’ phenomenon. Different rejuvenation policies are studied from the perspectives of design, implementations, and availability assessment. To evaluate these policies, stochastic reward net models are developed and solved by Stochastic Petri Net Package (SPNP). Numerical results show that the deployment of software rejuvenation in the system leads to significant improvement in capacity-oriented availability and reduction in downtime cost. The optimization of the rejuvenation interval in the time-based approach and the effect of the prediction coverage in the measurement-based approach are also studied in this paper.

Prioritized failure recovery in communication networks and its transient analysis

Prioritized recovery can provide differentiated recovery services to the users in communication networks. This paper studies the transient behavior of communication networks under prioritized recovery. Stochastic Petri net models are constructed to capture the behaviors of a queueing system at four different phases during the recovery process, i.e. failure-free phase, failure is detected, higher priority service is recovered, and lower priority service is recovered. The final state of the stochastic Petri net model in one phase is used as the initial state of the model in the next phase. Both the traffics for the higher and lower priority queue are modeled as Markov Modulated Poisson Processes. Two queues are served with round-robin fashion. With the help of Stochastic Petri Net Package (SPNP), the transient performances of the queueing system during each phase are numerically studied. The queue with the higher recovery priority significantly outperforms the queue with the lower recovery priority during the recovery process. A new concept about performance recovery is introduced. Performance recovery time, which is defined as the time required for a performance index to reach a desired and acceptable value, if it is deteriorated by the service disruption, is distinct from and more important than the failure recovery time. The models and analytical methods presented in this paper can be used to quantify the performance recovery time.

Performance of broadcast and unknown server (BUS) in ATM LAN emulation

In this paper, we develop performance models of the Broadcast and Unkn own Server (BUS) in the LANE. The traffic on the BUS is divided into two classes: the broadcast and multicast traffic, and the unicast relay flow. The broadcast and multicast traffic is assumed to form a Markov Modulated Poisson Process (MMPP). The traffic for a particular unicast relay flow is an MMPP as well. However, the number of active unicast relay flows sojourning on the BUS is determined by a tandem queueing system, where the flow arrival process is Poisson, the address resolution delay is exponentially distributed, and the connection setup delay is three-stage Erlang distributed. The size of data frames in traffic flows is a random variable with three possible values: short, medium, and large. In order to deal with the intractability (i.e., largeness and stiffness) of the underlying Markov chain, a hierarchical model is used to decompose the system. With the help of Stochastic Petri Net Package (SPNP), a software package for the automated generation and solution of Markovian stochastic systems, and the decomposition method, we study the performance of the BUS module under different loads. We also investigate the effect of address resolution delay and connection setup delay on the performance of the BUS.

An integrated reliability modeling environment

Abstract In this paper, we propose an integrated reliability/availability modeling and analysis environment suitable for heterogeneous hierarchical system analysis. A key component of this environment is a high level system specification and input language which acts as a common interface to several off-the-shelf reliability modeling and analysis tools (Koren JM, Gaertner J. CAFTA: a fault tree analysis tool designed for PSA. In: Proc. of Probabilistic Safety Assessment and Risk Management: PSA '87, Zurich, Switzerland, vol. 2, 1987:588–592; Sahner RA, Trivedi KS. Reliability modeling using SHARPE, IEEE Trans. Reliability R-36, 2 June 1987:186–193; Ciardo G, Muppala J, Trivedi K. SPNP: Stochastic Petri Net Package. In: Proc. 3rd Int. Workshop on Petri Nets and Performance Models, Kyoto, Japan, Dec. 1989:142–151; Smotherman MK, Dugan JB, Trivedi KS, Geist RM. The hybrid automated reliability predictor. AIAA Journal of Guidance, Control and Dynamics May/June 1986:319–331). The complexity of the underlying solvers for reliability analysis is kept transparent to the user by the design of a common language and translators to these tools. This design has several advantages including interoperability, ability of the interpreter to choose a particular solver depending on the problem characteristics and the ease of enhancing the system capability transparent to the user. The technique, being very compact in model description, also leads to a quick analysis of the design, guiding the designers at every stage for reliable product development.

A stochastic reward net model for performance analysis of prioritized DQDB MAN

The performance of prioritized distributed queue dual bus (DQDB) metropolitan area network (MAN) under bursty traffic environment is studied in this article. The tagged node model is adopted to simplify the analysis. The processes of the packet arrivals to the tagged node, the empty-slot pattern from the upstream, and the request pattern from the downstream are assumed to be Markov Modulated Poisson Processes, a more general and appropriate model to capture the bursty characteristics existing in the traffic flows in high-speed networks. A stochastic reward nets model for the prioritized DQDB MAN is presented. With the help of the stochastic petri net package developed in Duke University, the steady state and as well as the transient behavior of packet loss ratio of tagged node are investigated. The influence of the burstiness of the empty-slot pattern, packet arrival and request pattern on the tagged node’s performance are examined.

Automated construction of GSPN models for flexible manufacturing systems

Generalized stochastic Petri nets (GSPNs) are often used to specify flexible manufacturing systems (FMSs) and their control systems. While GSPNs are a powerful tool for system modeling, their complexity can become unmanageable for all but the simplest `toy' systems. Thus, manual construction of GSPNs can quickly become unacceptably slow and error-prone. In this paper, a formal method is developed to automatically construct a GSPN model for a given FMS. An FMS description language (FMSDL) is presented as the language for the input file of a GSPN construction program named FMSPet. FMSPet translates FMSDL input files into a GSPN system model, maps the specified process plans onto the given physical system, and attaches control stubs to resolve conflicts. The output GSPN is formatted as an input file for the stochastic Petri net package (SPNP) to support the analysis and evaluation of the structural and temporal properties of the net.

Scheduling printed circuit board production systems using the two-level scheduling approach

In this paper, the development of multiple-input multiple-output (MIMO) subnets is discussed. Hierarchical time-extended Petri nets (H-EPNs), a form of extended Petri nets, allow the development of structured MIMO subnets to model complex system functionalities. In addition, H-EPNs also provide a means to convert such a MIMO structure to a single-input single-output (SISO) net that can easily be integrated within a top-down system decomposition. The activator arc definition is instrumental in deriving this transformation. The activator arc definition and the H-EPN subnet definitions are integrated with the SPNP (stochastic Petri net package) for simulation and analysis purposes. The activator arc extension allows a truly hybrid approach to Petri net (PN)-based systems modeling, analysis, and development of complex PN models of automated manufacturing systems. The case study emphasizes the usefulness of this extension in studying important issues such as static priority scheduling, dynamic failure recognition, and rescheduling in manufacturing systems. The SPNP package, suitably modified to handle the H-EPN extensions, is used for analysis and verification.

Petri net extensions for the development of MIMO net models of automated manufacturing systems

Abstract In this paper, the development of multiple-input multiple-output (MIMO) subnets is discussed. Hierarchical time-extended Petri nets (H-EPNs), a form of extended Petri nets, allow the development of structured MIMO subnets to model complex system functionalities. In addition, H-EPNs also provide a means to convert such a MIMO structure to a single-input single-output (SISO) net that can easily be integrated within a top-down system decomposition. The activator arc definition is instrumental in deriving this transformation. The activator arc definition and the H-EPN subnet definitions are integrated with the SPNP (stochastic Petri net package) for simulation and analysis purposes. The activator arc extension allows a truly hybrid approach to Petri net (PN)-based systems modeling, analysis, and development of complex PN models of automated manufacturing systems. The case study emphasizes the usefulness of this extension in studying important issues such as static priority scheduling, dynamic failure recognition, and rescheduling in manufacturing systems. The SPNP package, suitably modified to handle the H-EPN extensions, is used for analysis and verification.

Modelling an automated storage and retrieval system using Petri nets

Abstract We investigated the feasibility of using stochastic Petri nets (SPNs) to describe the behaviours of automated storage/retrieval systems as well as to evaluate the performance of different control policies of such systems. SPNs have been studied in the past 2 decades, and have become a powerful tool in modelling concurrent and distributed systems that exhibit synchronization and contention of shared resources. It appeared that some important characteristics of AS/RS could be well modelled with SPNs. The SPN is a graph-based tool suitable for modelling systems (manufacturing, computer, biological, etc.). It can be used to model a system at different levels of abstraction. In this study, the efficiency, control rules, bay assignment, and many other performance issues associated with AS/RS have been studied in detail using SPN models. SPNs are shown to be equivalent to the stochastic processes in which embedded Markov chains can be recognized. In addition, a stochastic Petri net package, SPNP, was ad...

Modeling, analysis and simulation of failures in a materials handling system with extended Petri nets

This paper models, analyzes, accommodates and simulates potential failures which may occur in a materials handling system with extended Petri nets (EPNs). EPNs are shown to be able to cope with various important failure situations that occur in a manufacturing system through the definition of six different types of places. Detailed EPN based subnets are provided to study and accommodate occurred failures. The approach described proposes an efficient methodology to generate an overall EPN design to model and analyze potential system failures at different levels of detail. It has been observed that the study of boundedness properties rather than the safeness properties of a manufacturing system with resource constraints leads to a better defined EPN system model. The subnet structural properties and the overall system properties are preserved. The Stochastic Petri Net Package (SPNP) is used for simulation studies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>