Workflow-Based Modeling of Web Application and Automatically Generating Test Sequences

This paper describes model transformation for analyzing dynamic behavior of large-scale systems. The Unified Modeling Language (UML) based system model is transformed into the Colored Petri Nets (CPN) model, which is used for analyzing the scenarios of the use cases of a system and checking freedom of system deadlock at an early stage of software development. The CPN model that is executable is hierarchically structured on the basis of the functional decomposition of a large-scale system. The UML-based system model consisting of the use case model, class model and collaboration model is not executable so that the dynamic behavior of the system cannot be analyzed until implementation of the system. However, the UML-based system model has no hierarchical structure to be transformed into the hierarchical CPN model as well. The discrepancies of dynamic and structural views in the two models are resolved by transformation of the UML model into the layered, executable CPN model with three layers — the use case layer, object layer and operation layer. The model transformation is carried out using relationships among the use case model, class model, and collaboration model of the UML. With the executable CPN model transformed, the dynamic properties of the system are analyzed using the simulation technique, occurrence graph, and state space report provided by the Design/CPN tool. The approach in this paper is validated through two case studies — the gas station system and the distributed factory automation system.

Petri Nets provide a graphical notation for modeling systems and performing analysis. Colored Petri Nets (CPNs) combine the strengths of ordinary Petri Nets with a high level programming language, making them more suitable for modeling large systems. A CPN model is an executable representation of a system that can be analyzed through simulation. CPN models are built using CPN Tools, a graphical software tool and interface used to create, edit, simulate, and analyze models. This tutorial is meant to introduce the reader to the vocabulary and constructs of CPNs and illustrate the use of CPN Tools in creating and simulating models by means of a familiar, simple example. In particular, we show how to create a CPN model of the call center example presented by White and Ingalls in their tutorial Introduction to Simulation.

PurposeA major factor to the success of flexible manufacturing systems (FMSs) is their ability to transport work pieces between different workstations. FMS have now become more advanced and material‐handling systems have become progressively more sophisticated, it is not exceptional to have automated steering of tools to workstations as well. Such system design will improve the tool‐handling capability and the system productivity while holding tool cost to a minimum. Tool cost could represent as much as 25 percent of the operating cost. The purpose of this paper is to propose a new colored Petri net (CPN)‐based approach to the design and development of a tool sharing control system that is intended to help use of the proper and minimal number of tools for a manufacturing system.Design/methodology/approachA new black token timed PN model is first developed, to reduce the complexity of the graphical representation a new CPN model is developed. The new CPN model also allows to find the optimal sequence. The optimal sequence has no effect on the work in process (WIP) but it influences the number of tools used in the system. The main input to the PN model for a manufacturing system is the process plan. Next, all the invariants and total number of possible elementary circuits are determined using the Integrated Net Analyzer (INA) software. Output from the INA software is exported to the Excel spreadsheet. The Excel spreadsheet can be designed to calculate the total number of tokens, processing time, cycle time, etc. of each elementary circuit. Subsequently, the constraints used in Lingo will be created according to critical circuit rules. Finally, linear programming (LP) technique is used to optimize the WIP and tool inventory. Lingo software is used for the LP, the constraints from the Excel sheet will be the input data to the Lingo program, and based on those constraints the Lingo will provide the optimal values for the desired parameters. The output from Lingo will be used to recalculate the cycle time of each elementary circuit in the Excel sheet. The system is then analyzed before and after the implementation of the CPN model.FindingsA new CPN model based on tool‐sharing philosophy for an FMS with N part types and M stations is proposed.Originality/valueThe paper presents a new CPN‐based approach to the design and development of a tool sharing control system, that is, intended to help use of the proper and minimal number of tools for a manufacturing system. The new CPN model also allows to find the optimal sequence. The idea is new and pure and has not been presented before using the methodology adopted in this paper.

In a distributed embedded system, it is often necessary to share variables among its computing nodes to allow the distribution of control algorithms. It is therefore necessary to include a component in each node that provides the service of variable sharing. For that type of component, this paper discusses how to create a Colored Petri Nets (CPN) model that formally expresses the following elements in a clearly separated structure: (1) assumptions about the behavior of the environment of the component, (2) real-time requirements for the component, and (3) a possible solution in terms of an algorithm for the component. The CPN model can be used to validate the environment assumptions and the requirements. The validation is performed by execution of the model during which traces of events and states are automatically generated and evaluated against the requirements.

Security verification and performance analysis are both crucial aspects for designing effective and efficient authentication protocols. However, in most authentication protocol design practice, two independent models are often adopted for individual security verification and performance analysis, which could not guarantee that performance improvements taking no harm to its security functionalities. In this paper, a colored Petri nets (CPN) model based method is well utilized to integrate security verification and performance analysis for authentication protocols. The main idea is that the functional CPN model for an authentication protocol is constructed firstly for its security verification, and then performance related temporal constrains are added into above model to form a corresponding performance CPN model for simulation based performance evaluation towards that authentication protocol. Because such closely related CPN models are utilized where occurrence sequences existed in performance models are also behavior-equally existed in functional models, it is guaranteed that both models satisfy the security requirements for the authentication protocol. We present the security and performance joint analysis process of TRDP protocol, a representative example of authentication protocols, to illustrate the effectiveness of above CPN based integrated approach.

This thesis proposal suggests a model-based approach to obtain, from a set of behavioural scenarios of a given reactive software system, a graphical animation for reproducing that set of scenarios for validation purposes. The approach assumes that the requirements of the system are described by a use case diagram, being the behaviour of each use case detailed by a collection of scenario descriptions. These use cases and scenarios are transformed into a Coloured Petri Net (CPN) model, which is next complemented with animation-specific elements. By executing the CPN model, it is possible to animate the scenarios in a user-friendly way and thus ensuring an effective involvement of the users in the system's validation. The CPN model is enforced to be (1) parametric, allowing an easy modification of the initial conditions of the scenarios, (2) environment-descriptive, meaning that it includes the state of the relevant elements of the environment, and (3) animation-separated, implying that the elements related to animation are clearly separated from the other ones. We validate our approach based on its application to two examples of reactive systems.

Workflow model is useful for representing the activities of work process in business, but there are no tools to analyze and emulate it. In this paper, a series of rules are given which can map the ordinary workflow model into Colored Petri net (CPN) model, which is executable and analyzable in the CPN Tools environment. Some characteristics of the workflow, such as roles, activities, sub-processes, resources and other basic elements are represented with tokens, transitions, substitution transitions, places in the CPN respectively. Some basic structure elements (Sequence, and branches, and connection, or branches, or connections, selection branches) and basic control structures (Sequence structure, parallel structure, single choice, simple merge, cycle, multiple choice, multiple merge)are transformed into CPN models according to the rules given in this paper.

Information services play a crucial role in grid computing environments in that the state information of a grid system can be used to facilitate the discovery of resources and services available to meet user requirements and help tune the performance of the grid. This article models PIndex, which is a grouped peer-to-peer network with Colored Petri Nets (CPNs) for scalable grid information services. Based on the CPN model, a simulator is implemented for PIndex simulation and performance evaluation. The correctness of the simulator is further verified by comparing the results computed from the CPN model with the results generated by the PIndex simulator.

The travelling salesman problem, which can be solved with various methods, is a traditional and typical problem in artificial intelligence (AI). As an evolution of Petri nets, colored Petri nets (CPN) can be dedicated to modeling and analysis of different systems as a new attempt. The paper shows the brief description of the given problem and CPN, we detail the implementation of the CPN model of the problem and analyze the simulation result. This CPN example shows the potentiality of CPN application in AI.

Nowadays parallel software system is very common and practical. However, it is difficult to test parallel software, because the state space of parallel software is very large. Therefore, a parallel model simplification method based on CPN (Color Petri Net) is proposed. Based on the original CPN, the CPN model for the tested behavior(Tested Behavior of CPN, TBoCPN) is proposed. The target of the test is described as the tested behavior. The relevant behavior is described as the behavior related to the tested behavior, then, the homogeneous concurrent branch group and the selection branch set are divided. Finally, the branches of the concurrent branch group and the selected branch set, which satisfied the condition of algorithm, are sequentially processed by the inhibitor arcs. The experiment shows that the reduction rate is at least 60%, and before and after the reduction, the full coverage test path generated by the tested behavior is not affected, thus proving that the method is an effective test method.

This paper presents a formal security analysis of the ISA100.11a standard protocol using the Colored Petri Net (CPN) modeling approach. Firstly, we establish a security threat model for the ISA100.11a protocol and provide a detailed description and analysis of the identified security threats. Secondly, we use the CPN tool to model the protocol formally and conduct model checking and security analysis. Finally, we analyze and discuss the results of the model checking, which demonstrate that the ISA100.11a standard protocol may have vulnerabilities when certain security threats exist, and provide some suggestions to enhance the security of the protocol. This research provides a certain level of security assurance for the ISA100.11a standard protocol and serves as a reference for similar security research on protocols.

Server consolidation for heterogeneous computer clusters using Colored Petri Nets and CPN Tools

Data replication is a central mechanism for the engineering of fault-tolerant distributed systems, and is used in the realization of most cloud computing services. This paper explores the use of Coloured Petri Nets (CPNs) for model-based testing of quorum-based distributed systems. We have developed an approach to model-based testing of fault-tolerant services implemented using the Go language and the Gorums framework. We show how a CPN model can be used to obtain both unit test cases for the quorum logic functions, and system level test cases consisting of quorum calls. The CPN model is also used to obtain the test oracles against which the result of running a test case can be compared. We demonstrate the application of our approach by considering an implementation of a distributed storage service on which we obtain 100% code coverage for the quorum functions, 96.7% statement coverage on the quorum calls, and 52.3% coverage on the Gorums framework. We demonstrate similar encouraging results also on a more complex Gorums-based implementation of the Paxos consensus protocol.

The Petri net (PN) formalism is a suitable tool for modeling parallel systems due to its basic characteristics, such as synchronization. The extension of PN, the Colored Petri Nets (CPN) allows the incorporation of more details of the real system into the model (for example, contention for shared resources). The CPNs have been widely used in a variety of fields to produce suitable models. One of their biggest strengths is that their overall philosophy is quite similar to the philosophy of the object-oriented paradigm. In this regard, the CPN models can be used to implement simulators in a rather straightforward way. In this paper, the CPN framework is employed to implement a new resource allocation simulator, which is used to verify the performance of our previous work, where we proposed a fair resource allocation scheme with flow control and maximum utilization of the system’s resources.

This paper presents the results that we attained about modeling and simulation of the metallographic samples preparation and analysis automated systems, made of two subsystems. The first subsystem polishes the samples and assesses the surface state by means of a microscope. In the second subsystem the samples are reagent attacked, washed, dried and analyzed by the electronic microscope. The evaluation of the system performance and the identification of possible bottlenecks was made by means of coloured Petri nets modeling and simulation. The CPN Tools software was used to make the model. Three coloured Petri nets models were developed. The first version assumes the analysis of the system operation by means of coloured Petri nets with simple colours, and such a simple colour was assigned to each entity of the subsystem: samples to be analyzed, robots, storage devices, microscopes etc. For a better observation of the analyzed sample path within the system, the second model version was designed, with complex colours assigned to the marks. The third version considers the time factor. The models with timed coloured Petri nets allow the system performance evaluation considering the number of analyzed samples in a given time interval. This paper presents the first and the third model, as the last one includes the second model.