排队系统的着色Petri网建模与分析

着色Petri网（CPN）是研究离散事件动态系统的有力工具,将着色Petri网引入排队系统建模中,能弥补排队模型缺乏动态逻辑行为分析能力的不足。针对排队系统一般模型建立顶层结构模型,并对排队系统的4个要素给出了具体的CPN描述。给出一个具体实例,阐明排队系统的CPN分析法的使用,利用仿真工具CPN-Tools对模型仿真实现,仿真结果与数学模型得出的理论值对比分析,验证了可行性。     

基于Petri网的Web服务组合建模

针对Web服务组合流程进行建模,可以实现可靠的服务组合。文中首先提出了一种基于Petri网理论的Web服务组合建模方法,对服务组合进行形式化建模,然后通过分析Web服务网的可迭性和活性对Web服务组合进行验证,最后举例说明此方法的应用。     

基于颜色Petri网的Web服务组合建模及应用

给出了用颜色Petri网来对Web服务及服务组合建模,在描述服务内部控制结构的同时兼顾了数据流的描述,而且还给出了模拟Web服务执行的引发规则,从静态、动态两方面描述了Web服务及服务组合,最后还给出了一个应用颜色Petri网建模的实例。     

基于精炼操作的Petri网建模及其分析方法

针对复杂系统的Petri网建模及其分析问题,定义了Petri网的精炼操作及其相关的Petri网模型.基于序列投影,建立精炼Petri网与原网、子网间的动态行为关联关系,并分析了该精炼操作的相关动态性质,得到一组性质保持判据.最后,基于该方法实现了一个顺序资源共享系统的应用案例的建模及其分析.所提出的方法不仅为复杂系统的Petri建模提供了新的思路,而且有助于复杂Petri网模型的分析和验证.     

基于Petri网的Web服务组合建模与验证

该文首先提出了基于Petri网的Web服务组合建模方法,对服务组合进行形式化建模,然后采用可达树作为分析工具,对服务组合模型的可达性,活性,有界性等特性进行验证分析。最后通过一个具体的实例说明此方法的应用。     

基于Petri网的动态Web服务组合建模

基于广义随机Petri网,提出了一种动态Web服务组合建模的方法.利用广义随机Petri网(GSPN)以及OWL-S组合过程对Web服务组合过程构建动态组合模型,实现Web服务的动态组合.并通过一个实例证明该方法的可行性.与现有的方法相比,该方法可以更有效地描述动态Web服务组合.     

基于颜色Petri网的服务组合建模与验证

Web服务组合技术能快速、灵活的满足复杂多变的业务需求,Web服务组合及其形式化描述和验证已经成为Web服务中一个非常重要的研究方向.给出了一个基于颜色Petri网(CPN)的Web服务和Web服务组合的形式化定义和描述,主要描述了4种组合结构:顺序、选择、并发和循环.给出了一个颜色Petri网建模Web服务组合的实例,并且对模型进行了简单的正确性分析.分析结果表明,该建模方法满足正确性要求.     

基于Petri网的Web服务流程建模

Web服务流程模型的建立是实现Web服务集成的重要环节。研究了Web服务流程Petri网模型的建立及其正确性检验的方法，并给出了Petri模型中基本路由的BPEL4WS描述。     

基于层次着色Petri网的网构软件性能建模与仿真分析方法

网构软件由分布的、松耦合的服务按照一定的交互组合而成.由于服务的共享性,通常有多个软件系统请求服务节点上的同一服务.这些外部负载会影响服务进而影响网构软件的性能,因此在研究网构软件的性能时需要将这些外部负载考虑在内.基于上述问题,提出一种基于层次着色Petri网的网构软件性能建模与仿真分析方法.首先构建网构软件的性能模型,它包含一个顶层CPN和若干个子层CPN.顶层CPN建模网构软件的业务处理流程;子层CPN详细建模从请求服务到服务执行完成的过程.服务请求来自网构软件和其它软件系统.然后采用CPN Tools工具通过模型的仿真进行性能分析.最后通过仿真实验研究外部负载对服务进而对网构软件性能的影响.     

基于扩展颜色Petri网的Web服务组合建模及应用

该文提出一个基于扩展颜色Petri网的Web服务组合描述模型,该模型在描述组合流程的控制流和数据流的同时还能描述流程中的参数、操作的语义和服务质量,能较全面地刻画Web服务组合流程;最后通过该建模方法给出一个建模实例。     

Performance Modeling and Evaluation of Distributed Component-Based Systems Using Queueing Petri Nets

Performance models are used increasingly throughout the phases of the software engineering lifecycle of distributed component-based systems. However, as systems grow in size and complexity, building models that accurately capture the different aspects of their behavior becomes a more and more challenging task. In this paper, we present a novel case study of a realistic distributed component-based system, showing how Queueing Petri Net models can be exploited as a powerful performance prediction tool in the software engineering process. A detailed system model is built in a step-by-step fashion, validated, and then used to evaluate the system performance and scalability. Along with the case study, a practical performance modeling methodology is presented which helps to construct models that accurately reflect the system performance and scalability characteristics. Taking advantage of the modeling power and expressiveness of Queueing Petri Nets, our approach makes it possible to model the system at a higher degree of accuracy, providing a number of important benefits.     

Performance Analysis of Retrial Queueing Systems Using Generalized Stochastic Petri Nets

We consider retrial queueing systems, in which an arriving customer finding the server busy, may repeat his call after a random duration. The consideration of repeated calls introduces great analytical difficulties. In fact, detailed analytical results exist for some special retrial queueing systems, while for many others, the performance evaluation is limited to numerical algorithms, approximation methods and simulation. Retrial queues have been widely used to model many problems in telephone switching systems, telecommunication and computer networks. In this paper, we show a method of modelling and analysing retrial queueing systems, using the Generalized Stochastic Petri nets (GSPNs).     

Modeling and Analysis of Real-Time Cooperative Systems Using Petri Nets

The existing formal techniques are not suitable for elegantly modeling passing value indeterminacy and describing batch processing function in real-time cooperative systems. Moreover, the correct behavior of the systems depends on not only the logical correctness of the results obtained through running workflows but also the time of producing them before critical deadlines. For these purposes, this paper proposes an interorganizational logical workflow net (ILWN) for modeling and analyzing real-time cooperative systems based on time Petri nets, workflow techniques, and temporal logic. Through attaching logical expressions to some actions of an ILWN model, the size of the model is reduced. Thus, ILWNs can efficiently mitigate the state explosion problem to some extent. Also, this paper analyzes the soundness of a subclass of ILWNs: the or-restricted ILWNs. A rigorous analysis approach is given based on their static net structures only. The concepts and techniques proposed in this paper are illustrated with a seller-buyer example in electronic commerce.     

晶圆制造单元的Petri网建模和性能分析

晶圆制造是半导体制造过程中的一个重要环节,晶圆制造单元的性能直接影响晶圆制造的成本。为了有效地分析晶圆制造单元的动态性能,分别对加工设备存在瓶颈和搬运机器人存在瓶颈的两种情况,进行了赋时Petri网建模研究,建立了晶圆制造单元的赋时Petri网模型。在此基础上,进行了稳态生产率分析,同时用实例验证了模型的有效性和实用性。     

Modeling and Analysis of Workflows Using Petri Nets

A workflow system, in its general form, is basically a heterogeneous and distributed information system where the tasks are performed using autonomous systems. Resources, such as databases, labor, etc. are typically required to process these tasks. Prerequisite to the execution of a task is a set of constraints that reflect the applicable business rules and user requirements.In this paper we present a Petri Net (PN) based framework that (1) facilitates specification of workflow applications, (2) serves as a powerful tool for modeling the system under study at a conceptual level, (3) allows for a smooth transition from the conceptual level to a testbed implementation and (4) enables the analysis, simulation and validation of the system under study before proceeding to implementation. Specifically, we consider three categories of task dependencies: control flow, value and external (temporal).We identify several structural properties of PN and demonstrate their use for conducting the following type of analyses: (1) identify inconsistent dependency specifications among tasks; (2) test for workflow safety, i.e. test whether the workflow terminates in an acceptable state; (3) for a given starting time, test whether it is feasible to execute a workflow with the specified temporal constraints. We also provide an implementation for conducting the above analyses.     

Performance Evaluation of Asynchronous Concurrent Systems Using Petri Nets

Some analysis techniques for real-time asynchronous concurrent systems are presented. In order to model clearly the synchronization involved in these systems, an extended timed Petri net model is used. The system to be studied is first modeled by a Petri net. Based on the Petri net model, a system is classified into either: 1) a consistent system; or 2) an inconsistent system. Most real-world systems fall into the first class which is further subclassified into i) decision-free systems; ii) safe persistent systems; and iii) general systems. Procedures for predicting and verifying the system performance of all three types are presented. It is found that the computational complexity involved increases in the same order as they are listed above.     

多主体行为模拟的层次Petri网方法

对多主体系统中主体行为间关系进行准确的描述和分析是保证多主体系统顺利运行的关键因素之一。与已有的基于Petri网的方法不同,该文将主体的动作分类为内部和外部动作,利用Petri网系统描述单个主体的内部结构,进而得到多主体系统的层次Petri网系统模型,每个主体的内部结构在系统网系统中表现为一个替代变迁元素,如此可以从两个层次（系统层和主体层）上对多主体系统的各种动态行为间的关系,特别是并发关系进行描述和分析。     

Hybrid Petri Nets for Modeling and Analysis of Microgrid Systems

Hybrid Petri nets (HPNs) are widely used to describe and analyze various industrial hybrid systems that have both discrete-event and continuous discrete-time behaviors. Recently, many researchers attempt to utilize them to characterize power and energy systems. This work proposes to adopt an HPN to model and analyze a microgrid that consists of green energy sources. A reachability graph for such a model is generated and used to analyze the system properties.      

Modeling Multithreaded Applications Using Petri Nets

Since most modern computing systems contain multiple processing elements, applications are relying on multithreaded programming techniques that allow a program to execute multiple tasks concurrently to take advantage of the processing capabilities. Multithreaded programs are more difficult to design and test because of the nondeterministic execution orders and synchronization among the threads. Different approaches can be used to test Multithreaded Applications. In our approach we use Petri nets to represent the key elements of interactions among threads to identify potential problems such as race conditions, lost signals, and deadlocks. A tool called C2Petri has been developed which converts C-Pthreads programs to the equivalent Petri net model. This tool helps verification of Pthread-based programs. At present the tool has limited capabilities and we hope to expand the capabilities of our tool in the near future.