Behavior, Interaction, Priority Research Articles

Correct-by-construction model-based design of reactive streaming software for multi-core embedded systems

We present a model-based design approach toward correct-by-construction implementations of reactive streaming software for multi-core systems. A system’s implementation is derived from a high-level process network model by applying semantics-preserving model transformations. The so-called fixed priority process networks (FPPNs) are programmed independently from the execution platform and combine streaming and reactive control behavior with task parallelism for utilizing multi-core processing. We first define the FPPN sequential execution semantics that specifies precedence constraints between job executions of different tasks. Applications are thus rendered such that for any given test stimuli, a deterministic output response is expected. Furthermore, we define the FPPN real-time semantics based on a timed-automata modeling framework. This is provably a functionally equivalent semantics specifying the real-time execution of FPPNs and enabling runtime managers for scheduling jobs on multi-cores. A model transformation framework has been developed for deriving executable implementations of FPPNs on the BIP (Behavior–Interaction–Priority) runtime environment, ported on multi-core platforms. Schedulability is established by static analysis of the FPPN, and it is guaranteed by construction. Thus, the developers do not need to program low-level real-time OS services (e.g., for task management) and applications are amenable to testing, as opposed to if their outputs would depend on timing behavior. We have successfully ported a guidance-navigation and control application of a satellite system, onto a radiation hardened multi-core platform. Various implementation scenarios for efficiently utilizing HW resources are illustrated, and the test results are discussed.

A Study on Security Issues in the Internet of Things (IoT)

Remote correspondence systems are exceedingly inclined to security dangers. The actual uses of remote correspondence systems come in military, business, medicinal services, retail, furthermore, transportations. These frameworks utilize wired, cell, or adhoc systems. Our methodology depends upon vitality mindful types of the IoT application's plan in the BIP (Behavior, Interaction, Priority) segment system. This takes into account a nitty gritty formal portrayal of the framework's conduct and its resulting approval, consequently giving input to improvements in the pre-arrangement or pre-creation stages. The structure and advancement of a property security framework, in light of human movement identification and remotely checking innovation, to affirm guest personality and to manage Door openness has been accounted for in this paper. This paper portrays in regards to the execution and sending of remote control framework and openness directly into a property situation for confirmed individuals because it were. A PIR movement sensor and Camera module are utilized to identify movement and catch pictures separately are dedicatedly make the security framework alive as per the solicitation. Electromagnetic entryway lock module work the entryway openness, has been structured and created.

Process Network Models for Embedded System Design Based on the Real-Time BIP Execution Engine

Existing model-based processes for embedded real-time systems support the analysis of various non-functional properties, most notably schedulability, through model checking, simulation or other means. The analysis results are then used for modifying the system's design, so that the expected properties are satisfied. A rigorous model-based design flow differs in that it aims at a system implementation derived from high-level models by applying a sequence of semantics-preserving transformations. Properties established at any design step are preserved throughout the subsequent steps including the executable implementation. We introduce such a design flow using a process network model of computation for application design at a high level, which combines streaming and reactive control processing with task parallelism. The schedulability of the so-called FPPNs (Fixed Priority Process Networks) is well-studied and various solutions have been presented. This article focuses on the design flow's steps for deriving executable implementations on the BIP (Behavior - Interaction - Priority) runtime environment. FPPNs are designed using the TASTE toolset, a convenient architecture description interface. In this way, the developers do not program explicitly low-level real-time OS services and the schedulability properties are guaranteed throughout the design steps by construction. The approach has been validated on the design of a real spacecraft on-board application that has been scheduled for execution on an industrial multicore platform.

DesignBIP: A Design Studio for Modeling and Generating Systems with BIP

The Behavior-Interaction-Priority (BIP) framework, rooted in rigorous semantics, allows the construction of systems that are correct-by-design. BIP has been effectively used for the construction and analysis of large systems such as robot controllers and satellite on-board software. Nevertheless, the specification of BIP models is done in a purely textual manner without any code editor support. To facilitate the specification of BIP models, we present DesignBIP, a web-based, collaborative, version-controlled design studio. To promote model scaling and reusability of BIP models, we use a graphical language for modeling parameterized BIP models with rigorous semantics. We present the various services provided by the design studio, including model editors, code editors, consistency checking mechanisms, code generators, and integration with the JavaBIP tool-set.

Model-Based Design of Energy-Efficient Applications for IoT Systems

A major challenge that is currently faced in the design of applications for the Internet of Things (IoT) concerns with the optimal use of available energy resources given the battery lifetime of the IoT devices. The challenge is derived from the heterogeneity of the devices, in terms of their hardware and the provided functionalities (e.g data processing/communication). In this paper, we propose a novel method for (i) characterizing the parameters that influence energy consumption and (ii) validating the energy consumption of IoT devices against the system's energy-efficiency requirements (e.g. lifetime). Our approach is based on energy-aware models of the IoT application's design in the BIP (Behavior, Interaction, Priority) component framework. This allows for a detailed formal representation of the system's behavior and its subsequent validation, thus providing feedback for enhancements in the pre-deployment or pre-production stages. We illustrate our approach through a Building Management System, using well-known IoT devices running the Contiki OS that communicate by diverse IoT protocols (e.g. CoAP, MQTT). The results allow to derive tight bounds for the energy consumption in various device functionalities, as well as to validate lifetime requirements through Statistical Model Checking.

Modularizing behavioral and architectural crosscutting concerns in formal component-based systems – Application to the Behavior Interaction Priority framework

We define a method to modularize crosscutting concerns in Component-Based Systems (CBSs) expressed using the Behavior Interaction Priority (BIP) framework. Our method is inspired from the Aspect Oriented Programming (AOP) paradigm which was initially conceived to support the separation of concerns during the development of monolithic systems. BIP has a formal operational semantics and makes a clear separation between architecture and behavior to allow for compositional and incremental design and analysis of systems. We distinguish local from global aspects. Local aspects model concerns at the component level and are used to refine the behavior of components. Global aspects model concerns at the architecture level, and hence refine communications (synchronization and data transfer) between components. We formalize local and global aspects as well as their composition and integration into a BIP system through rigorous transformation primitives. We present AOP-BIP, a tool for Aspect-Oriented Programming of BIP systems, demonstrate its use to modularize logging, security, and fault tolerance in a network protocol, and discuss its possible use in runtime verification of CBSs.

From high-level modeling toward efficient and trustworthy circuits

Behavior–interaction–priority (BIP) is a layered embedded system design and verification framework that provides separation of functionality, synchronization, and priority concerns to simplify system design and to establish correctness by construction. BIP framework comes with a runtime engine and a suite of verification tools that use D-Finder and NuSMV as model-checkers. In this paper, we provide a method and a supporting tool that take a BIP system and a set of invariants and compute a reduced sequential circuit with a system-specific scheduler and a designated output that is \(\mathtt {true}\) when the invariants hold. Our method uses ABC, a sequential circuit synthesis and verification framework, to (1) generate an efficient circuit implementation of the system that can be readily translated into FPGA or ASIC implementations and to (2) verify the system and debug it in case a counterexample is found. Moreover, we generate a concurrent C implementation of the circuit that can be directly used for runtime verification. We evaluated our method with two benchmark systems, and our results show that, compared to existing techniques, our method is faster and scales to larger sizes.

Concurrency-preserving and sound monitoring of multi-threaded component-based systems: theory, algorithms, implementation, and evaluation

Abstract This paper addresses the monitoring of logic-independent linear-time user-provided properties in multi-threaded component-based systems. We consider intrinsically independent components that can be executed concurrently with a centralized coordination for multiparty interactions. In this context, the problem that arises is that a global state of the system is not available to the monitor. A naive solution to this problem would be to plug in a monitor which would force the system to synchronize in order to obtain the sequence of global states at runtime. Such a solution would defeat the whole purpose of having concurrent components. Instead, we reconstruct on-the-fly the global states by accumulating the partial states traversed by the system at runtime. We define transformations of components that preserve their semantics and concurrency and, at the same time, allow to monitor global-state properties. Moreover, we present RVMT-BIP, a prototype tool implementing the transformations for monitoring multi-threaded systems described in the Behavior, Interaction, Priority (BIP) framework, an expressive framework for the formal construction of heterogeneous systems. Our experiments on several multi-threaded BIP systems show that RVMT-BIP induces a cheap runtime overhead.

Component based computational model for bipedal locomotion

Bipedal locomotion has been an active area of research for many decades, it has wide ranging applications in the field of humanoid locomotion, as well as in the understanding of the biomechanics of normal human gait. Inherently human gait is a complex non-linear dynamic system, which is usually modeled by a set of differential equations satisfying a given set of constraints. In this paper an attempt has been made to view gait from the perspective of software engineering. In doing so, the entire gait cycle has been discretized into phases and sub-phases and modeled using a hybrid automaton, subsequently the automaton has been integrated with the BIP(Behavior, Interaction, Priority) framework, thereby creating a component based computational framework for modeling biped locomotion. The correctness of the developed model has been validated and verified through simulation runs in OpenSim.

Design and Analysis of Distributed Embedded Systems using AADL - Application to the Precision Time Protocol

Prototyping distributed embedded system can be seen as a collection of many requirements covering many domains. System designers and developers need to describe both functional and nonfunctional requirements. Building distributed systems is a very tedious task since the application has to be verifiable and analyzable. Architecture Analysis and Design Language (AADL) provides adequate syntax and semantics to express and support distributed embedded systems. This paper studies a general methodology for translating AADL thread component depending on the thread implementation into the BIP (Behavior Interaction Priority) language and for prototyping distributed applications using the Precision Time Protocol (PTP) for building and translating AADL systems into a distributed application using network communication protocol. This allows simulation of systems specified in AADL to fully assess system viability, to refine and to correct the behavior of the system using the BIP (Behavior Interaction Priority) toolset.

Statistical model checking QoS properties of systems with SBIP

Behavior–interaction–priority (BIP) is a component-based framework supporting rigorous design of embedded systems. BIP supports incremental design of large systems from atomic components that communicate via connectors and whose interactions can be described with a powerful algebra. This paper presents SBIP, an extension of BIP for stochastic systems. SBIP offers the possibility to add stochastic information to atomic component’s behaviors, and hence to the entire system. Atomic component’s semantics in SBIP is described by Markov Chains. We show that the semantics of the entire system is described by a Markov chain, showing that the non-determinism arising from system interactions is automatically eliminated by BIP. This allows us to verify systems described in SBIP with Statistical Model Checking. This paper introduces SBIP and illustrates its usability on several industrial case studies.

A Component-Based Modeling and Validation Method for PLC Systems

Programmable logic controllers (PLCs) are complex embedded systems that are widely used in industry. This paper presents a component-based modeling and validation method for PLC systems using the behavior-interaction-priority (BIP) framework. We designed a general system architecture and a component library for a type of device control system. The control software and hardware of the environment were all modeled as BIP components. System requirements were formalized as monitors. Simulation was carried out to validate the system model. A realistic example from industry of the gates control system was employed to illustrate our strategies. We found a couple of design errors during the simulation, which helped us to improve the dependability of the original systems. The results of experiment demonstrated the effectiveness of our approach.

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.

Rigorous System Design

The monograph advocates rigorous system design as a coherent and accountable model-based process leading from requirements to correct implementations. It presents the current state of the art in system design, discusses its limitations, and identifies possible avenues for overcoming them.A rigorous system design flow is defined as a formal accountable and iterative process composed of steps, and based on four principles: (1) separation of concerns; (2) component-based construction; (3) semantic coherency; and (4) correctness-by-construction. The combined application of these principles allows the definition of a methodology clearly identifying where human intervention and ingenuity are needed to resolve design choices, as well as activities that can be supported by tools to automate tedious and error-prone tasks. An implementable system model is progressively derived by source-to-source automated transformations in a single host component-based language rooted in well-defined semantics. Using a single modeling language throughout the design flow enforces semantic coherency. Correct-by-construction techniques allow well-known limitations of a posteriori verification to be overcome and ensure accountability. It is possible to explain, at each design step, which among the requirements are satisfied and which may not be satisfied.The presented view for rigorous system design has been amply implemented in the BIP (Behavior, Interaction, Priority) component framework and substantiated by numerous experimental results showing both its relevance and feasibility.The monograph concludes with a discussion advocating a systemcentric vision for computing, identifying possible links with other disciplines, and emphasizing centrality of system design.

A framework for automated distributed implementation of component-based models

Although distributed systems are widely used nowadays, their implementation and deployment are still time-consuming, error-prone, and hardly predictable tasks. In this paper, we propose a method for producing automatically efficient and correct-by-construction distributed implementations from a model of the application software in Behavior, Interaction, Priority (BIP). BIP is a well-founded component-based framework encompassing high-level multi-party interactions for synchronizing components (e.g., rendezvous and broadcast) and dynamic priorities for scheduling between interactions. Our method transforms an arbitrary BIP model into a Send/Receive BIP model that is directly implementable on distributed execution platforms. The transformation consists in (1) breaking the atomicity of actions in components by replacing synchronous multiparty interactions with asynchronous Send/Receive interactions; (2) inserting distributed controllers that coordinate the execution of interactions according to a user-defined partition of interactions, and (3) adding a distributed algorithm for handling conflicts between controllers. The obtained Send/Receive BIP model is proven observationally equivalent to its corresponding initial model. Hence, all functional properties of the initial BIP model are preserved by construction in the implementation. Moreover, the obtained Send/Receive BIP model can be used to automatically derive distributed executable code. The proposed method is fully implemented. Currently, it is possible to generate C++ implementations for (1) TCP sockets for conventional distributed communication, (2) MPI for multi-processor platforms, and (3) POSIX threads for deployment on multi-core platforms. We present four case studies and report experimental results for different design choices including partition of interactions and choice of algorithm for distributed conflict resolution.

Rigorous Component-Based System Design Using the BIP Framework

Rigorous system design requires the use of a single powerful component framework allowing the representation of the designed system at different detail levels, from application software to its implementation. A single framework allows the maintenance of the overall coherency and correctness by comparing different architectural solutions and their properties. The authors present the BIP (behavior, interaction, priority) component framework, which encompasses an expressive notion of composition for heterogeneous components by combining interactions and priorities. This allows description at different abstraction levels from application software to mixed hardware/software systems. A rigorous design flow that uses BIP as a unifying semantic model derives a correct implementation from an application software, a model of the target architecture, and a mapping. Implementation correctness is ensured by applying source-to-source transformations that preserve correctness of essential design properties. The design is fully automated and supported by a toolset including a compiler, the D-Finder verification tool, and model transformers. The authors present an autonomous robot case study to illustrate BIP's use as a modeling formalism as well as crucial aspects of the design flow for ensuring correctness.