Formal Modeling Method Research Articles

Formal modeling and verification of an enhanced variant of the IEEE 802.11 CSMA/CA protocol

In this paper, we present a formal method for modeling and checking an enhanced version of the carrier sense multiple access with collision avoidance protocol related to the IEEE 802.11 MAC layer, which has been proposed as the standard protocol for wireless local area networks. We deal mainly with the distributed coordination function (DCF) procedure of this protocol throughout a sequence of transformation steps. First, we use the unified modeling language state machines to thoroughly capture the behavior of wireless stations implementing a DCF, and then translate them into the input language of the UPPAAL model checking tool, which is a network of communicating timed automata. Finally, we proceed by checking of some of the safety and liveness properties, such as deadlock-freedom, using this tool.

Embedded Software Formalization Testing Method and its Application in Missile-Borne Software

The formal modeling method can accurately describe systems. Using formal method to test software improves the efficiency of software testing and it is comprehensive. Common real-time embedded software formal testing methods include Z language, finite state machine (FSM) and unified modeling language (UML), Petri net and time input/output automata (TIOA). This paper analyzes the characteristics of embedded software testing. The above formal methods and test case coverage criterions and test data collection methods are introduced. Combined with the characteristics of missile-borne software, this paper presents suitable ideas of testing missile-borne software.

A TLM-Based Platform to Specify and Verify Component-Based Real-Time Systems

This paper is about modeling and verification languages with their pros and cons. Modeling is dynamic part of system development process before realization. The cost and risky situations obligate designer to model system before production and modeling gives designer more flexible and dynamic image of realized system. Formal languages and modeling methods are the ways to model and verify systems but they have their own difficulties in specifying systems. Some of them are very precise but hard to specify complex systems like TRIO, and others do not support object oriented design and hardware/software co-design in real-time systems. In this paper we are going to introduce systemC and the more abstracted method called TLM 2.0 that solved all mentioned problems.

The Formal Verification and Improvement of Simplified SET Protocol

Model checking has been successfully applied to verify the security properties of network protocols. In this paper, we propose a formal modeling method using the PROMELA language based on simplified model of SET payment protocol proposed by Lu & Smolka, and use LTL to describe authentication property. Under the hypothesis of the network environment being controlled by the intruder, we use SPIN to find the attacks and improve the verification efficiency by using the optimization strategies of atomic steps and Bit-state hashing technology. Finally, we improve the existing vulnerabilities of the SET protocol. Index Terms—Model checking, SET protocol, Payment process, Vulnerabilities.

Modeling and Analysis for CPS Physical Entities Based on Spatio-Temporal Petri Net

CPS is a kind of multidimensional complex system fused with computing system, physical environment and network environment. CPS achieves the target of real-time perception and dynamic control of physical environment by the organic integration of 3C operations and depth of their cooperation. However, CPS also faces enormous challenges. Since CPS is a kind of large, heterogeneous, distributed and real-time feedback system which is integrated with multiple heterogeneous subsystem via the network, its system complexity is above the general information system. And the introduction of physical entities control system brings tremendous difficulties to development as well as its system complexity. This paper conducts a detailed analysis of the characteristics of the physical aspects of CPS and studies CPS’s physical entities of the properties and their location changes process in-depth. Then we propose a formal modeling method of physical entities in CPS by constructing a Spatial-Temporal Petri net model introducing space factor into the traditional Timed Petri net, which not only able to describe logical and time-level the behavior of physical entities, but also the changes of state caused by the position change of the physical entity. At last an example of robot control system proves the effectiveness of spatial and temporal Petri net models.

Formal Interpretation of Assertion Based Features on AMS Designs

The paper proposes the adoption of formal methods for modeling of analog functions. It explains how assertions can be overlaid onto the range of values of individual features in an analog function, and proceeds toward building a mathematical (hybrid automata) model to represent and analyze them. An LDO regulator and a battery charger are used as examples.

Probabilistic verification of a biodiesel production system using statistical model checking

Biochemical system designers are increasingly using formal modelling, simulation, and verification methods to improve the understanding of complex systems. Probabilistic models can incorporate realistic stochastic dynamics, but creating and analysing probabilistic models in a formal way is challenging. In this work, we present a stochastic model of biodiesel production that incorporates an inexpensive test of fuel quality, and we validate the model using statistical model checking, which can be used to evaluate simple or complex temporal properties efficiently. We also describe probabilistic simulation and analysis techniques for stochastic hybrid system (SHS) models to demonstrate the properties of our model. We introduce a variety of properties for various configurations of the reactor as well as results of testing our model against the properties.

Aspect-oriented design method for embedded systems based on timed statecharts

The formal modelling and verification method has become an effective way of improving the reliability and correctness of complex, safety-critical embedded systems. Statecharts are widely used to formally model embedded applications, but they do not realise the reasonable separation of system concerns, which would result in code scattering and tangling. Aspect-Oriented Software Development (AOSD) technology could separate crosscutting concerns from core concerns and identify potential problems in the early phase of the software development life cycle. Therefore, the paper proposes aspect-oriented timed statecharts (extended timed statecharts with AOSD) to separately model base functional requirements and other requirements (e.g., scheduling, error handling), thereby improving the modularity and development efficiency of embedded systems. Furthermore, the dynamic behaviours of embedded systems are simulated and analysed to determine whether the model satisfies certain properties (e.g., liveness, safety) described by computation tree logic formulae. Finally, a given case demonstrates some desired properties processed with respect to the aspect-oriented timed statecharts model.

Formal component-based modeling and synthesis for PLC systems

Programmable Logic Controllers (PLCs) are widely used in industry. PLC systems are reactive systems which run cyclically. In each cycle, the system state is checked and the program is executed once to determine the system behavior for a single cycle. Development of PLC systems conventionally follows the V-model, but increasing demand for efficiency and reliability requires a new rigorous and rapid design flow. In this paper, we propose a component-based formal modeling and synthesis method for cyclic execution platforms and apply it to PLC. Our method consists of three main phases: modeling, verification and code synthesis. In the modeling phase, the BIP (Behavior–Interaction–Priority) framework which is flexible and expressive is used as the modeling language. Real-time behavior, which is intensely concerned in PLC systems, can be modeled as well. In the verification phase, the system model is translated to timed automata and checked by Uppaal. Verification helps to ensure correctness of the model and further increases reliability of the implementation. In the code synthesis phase, the software part of the system model is extracted and synthesized to cyclic code. Although the PLC software runs cyclically, the software model is not necessarily given in a cyclic manner. We propose an algorithm which can generate high-performance cyclic code from a model which describes the business work-flow. This feature significantly simplifies program development. A set of tools is implemented to support our design flow and they are applied to an industrial case study for a PLC system that controls dozens of physical devices in a huge palace.

Towards Realising FollowMe User Profiles for Macro-Intelligent Environments

In this paper, we introduce the concept of a Large-Scale Intelligent Environment (LSIE) and provide an introduction to the use of bigraphs as a formal method for description and modelling. We then propose our MacroIE model as a solution to the LSIE problem and describe how that model may be implemented to achieve a continuity-of-experience to end users as they travel from place-to-place (a technology we call FollowMe). Our initial experiments with these implementations are presented, providing some valuable insights and promise for future refinement towards real-world deployment.

CPN-Based Modeling and Analysis of Shared Multi-Channel Cache CMP Architecture

As a formal modeling and analysis method, colored petri nets (CPN) fits to construct formal model for software/hardware system with lots of communication and parallel/synchronous sharing behavior. Then behavior analysis of system function and performance based on the CPN model can be unfolded to verify the system feasibility. The CPN model of a kind of new CMP architecture shared multi-channel L2 Cache (AUMCC) is constructed in this article. Processing simulating of instruction set is deeply penetrated on the AUMCC CPN model, and analysis based on simulating results well verifies the feasibility of AUMCC architecture.

Integration of Automatic Theorem Provers in Event-B Patterns

Event-B is a formal method for the system level modeling and analysis of dependable applications. It is supported by an open and extendable Eclipse-based tool set called Rodin. In this paper we proposed using Automatic theorem provers known as SMT-solvers with event-B pattern. The benefits of that are to reduce the proving effort, to reuse a model and to increase the degree of automation. The proposed approach has been applied successfully on two different case studies. The goal of the work presented in this paper is to study the possibility of enhancing event-b patterns. We want to bring the Satisfiability Modulo Theory (SMT) into formal methods and in particular SMT-solvers tools into event-B patterns. It considers the POs generated in the Rodin Platform and using SMT-solvers and Pattern design tools. This approach should also be readily applied in other development environments. For our purposes we apply the proposed approach on two case studies of a sequential algorithms first binary search algorithm. The second case study is finding the minimum value of an array of natural numbers. We design pattern and prove the correctness of binary search algorithm automatically discharges a part of the proof obligations and also provides the interactive prover to discharge the remaining proofs. The rest of the paper is organized as follows. The next section presents the main concepts then section three introduces the literature review. The proposal

Formal Modeling and Verification for Web Service Composition

Web service composition is an important reuse way of service resources,through which large scale and complex applications based on Internet can get the newer and more reliable resources among the distributed nodes.An important challenge for web services composition is how to ensure the correctness and reliability of the composition process. CPN(Colored Petri Net)as a formal modeling and verification method not only provides formal semantics and a number of analysis techniques,but also is independent of the concrete flow description language(e.g. BPEL, WSCDL ).This paper presents an approach of formal modeling and verifying for web service composition and uses an instance to illustrate it.

Modelling An Automatic Proof Generator For Functional Dependency Rules Using Colored Petri Net

Database administrators need to compute closure of functional dependencies (FDs) for normalization of database systems and enforcing integrity rules. Colored Petri net (CPN) is a powerful formal method for modelling and verification of various systems. In this paper, we modelled Armstrong's axioms for automatic proof generation of a new FD rule from initial FD rules using CPN. For this purpose, a CPN model of Armstrong's axioms presents and initial FDs considered in the model as initial color set. Then we search required FD in the state space of the model via model checking. If it exists in the state space, then a recursive ML code extracts the proof of this FD rule using further searches in the state space of the model.

Formalizing Cloud Service Interactions

Today, Cloud computing offer IT resources in the form of services. With increasing diversity and complexity of cloud services, a formal modeling method for cloud service interactions is required. In this paper, after introducing basic concept of Cloud computing and cloud services, then a formal modeling method of service interaction based on π-calculus is proposed. Next, a cloud service interaction pattern is given and is modeled by π-calculus. According to π-calculus response rules, the interaction pattern is deduced and the result verified its correctness. It is shown that π-calculus is competent to model dynamic interaction behavior of cloud services. The work reported in this paper provides a theoretical foundation for modeling and analysis of cloud service interactions.

Developing Reliable yet Flexible Software through If-Then Model Transformation Rules

Developing reliable yet flexible software is a hard problem. Although modeling methods enjoy a lot of advantages, the exclusive use of just one of them, in many cases, may not guarantee the development of reliable and flexible software. Formal modeling methods ensure reliability because they use a rigorous approach to software development. However, lack of knowledge and high cost practically force developers to use semi-formal methods instead. Semi-formal (visual) modeling methods, which are widely used in practical large-scale software development, are not good enough for reliable software development. This paper proposes a new approach to the development of reliable yet flexible software by transforming formal and semi-formal models into each other. In this way, the advantages of both methods are incorporated in to the software development process. The structured rules, proposed in this paper, transform formal and visual models into each other through the iterative and evolutionary process. The feasibility as well as the effectiveness of the proposed approach is demonstrated using the multi-lift system as a test case.

Toward the Optimal dose Metric in Continuous Renal Replacement Therapy

There is no consensus on the optimal method to measure delivered dialysis dose in patients with acute kidney injury (AKI). The use of direct dialysate-side quantification of dose in preference to the use of formal blood-based urea kinetic modeling and simplified blood urea nitrogen (BUN) methods has been recommended for dose assessment in critically-ill patients with AKI. We evaluate six different blood-side and dialysate-side methods for dose quantification. We examined data from 52 critically-ill patients with AKI requiring dialysis. All patients were treated with pre-dilution CVVHDF and regional citrate anticoagulation. Delivered dose was calculated using blood-side and dialysis-side kinetics. Filter function was assessed during the entire course of therapy by calculating BUN to dialysis fluid urea nitrogen (FUN) ratios q/12 hours. Median daily treatment time was 1,413 min (1,260-1,440). The median observed effluent volume per treatment was 2,355 mL/h (2,060-2,863) (p<0.001). Urea mass removal rate was 13.0 ± 7.6 mg/min. Both EKR (r²=0.250; p<0.001) and KD (r²=0.409; p<0.001) showed a good correlation with actual solute removal. EKR and KD presented a decline in their values that was related to the decrease in filter function assessed by the FUN/BUN ratio. Effluent rate (mL/kg/h) can only empirically provide an estimated of dose in CRRT. For clinical practice, we recommend that the delivered dose should be measured and expressed as KD. EKR also constitutes a good method for dose comparisons over time and across modalities.

A Formal Modeling Method for Grid Workflow Based on Concurrent Transaction Logic

Grid workflow is an important means to implement the cooperation of resources in the grid and becomes a key alternative to develop truly distributed applications for the grid platform. Grid workflow modeling is the basis of the establishment and execution of workflows. However, it is a challenging task for grid workflow modeling, due to the high degree of autonomy and heterogeneity of the cooperative organizations under distributed environments. Recently, Concurrent TRansaction logic (CTR) has become one of the most exciting methods for grid process modeling. In this paper, we present our current work for the modeling and controlling execution of grid workflow by CTR technique. We describe in detail the syntax of modeling method and summarize special communication primitives from which any process can be defined and understood by their interactive behaviors. The proposed method can provide some new functions like implementing comprehensive coordination and cooperation behaviors of different business processes to improve the stability of grid workflow system. Experimental results show that the proposed method works well for characterizing the behaviors and interactions of the workflow processes under heterogeneous environments in terms of the semantics of CTR.

Hierarchical Colored Petri Nets Based Modeling and Analyzing for Web Service Composition

Web services composition is a complex and error-prone process, but there are no effective verification mechanisms among the existing composition specifications. Based on the semantics of web services ontology language OWL-S, a formal description and modeling method using Hierarchical Colored Petri nets(HCPN) for web services composition processes is proposed. In the method, the control and data flow information of web services composition process model which is described by the OWL-S can be transformed into HCPN model, with the ease of simulation and verification. On the other hand, the state space explosion problem can be transfered into the memory limit of computer which is not a serious problem now. With the help of CPN-Tools, the established HCPN model can be simulated dynamicly, the dynamic behaviors of the model can be obtained, and the correctness and effectiveness of web services composition can be verified. The method can be used to analyze and verify complex systems. An instance of hospital services is given to illustrate the modeling and analysis of the service composition process with HCPN.

The Petri Nets as a Formal Modeling Method in Systems Biology

ペトリネットは細胞内の反応経路や遺伝子・たん白質等の制御関係をモデル化するための形式的手法として活発に研究され，最近ではシステム生物学の道具の一つとして定着しつつある．最近のシステム生物学における形式的モデル化手法の研究動向についてペトリネットの特徴を踏まえながら紹介した後に，細胞内反応経路解析へのペトリネット理論の適用例について簡単に述べ，更に筆者が主に研究しているハイブリッドペトリネットによって生物時計モデルを作成しシミュレーション実行した応用例について述べる．