Slicing Executable System-of-Systems Models for Efficient Statistical Verification

Through the increasing complexity and dynamics of industrial automation scenarios, the notion of Systems of Systems (SoS) has gained importance in this field. Here, interconnected constituent (hardware as well as software) systems collaborate in order to achieve common goals and to increase the efficiency of certain industrial applications.The Arrowhead Tools project aims at proposing a comprehensive, flexible platform for supporting SoS engineering in its every phase, in the form of an engineering toolchain. Thereby, although the SoS operation aspect has been already elaborated on, the design phase and the usage of design artifacts as part of a continous tool interoperability scenario received less attention so far. In this paper, we describe such a toolchain interoperability scenario, paving the way towards an established, integrated solution, by linking systems modeling practices with SoS operational management. In particular, we propose a customtailored abstract SysML profile for Arrowhead SoS design, and a prototype implementation for a bidirectional link between SoS models and a tool for managing Arrowhead SoS via a customtailored textual format. We illustrate the approach through a realistic industrial application.

Behavior models are key models in SoS (System of Systems) modeling and simulation in aircraft top-level demonstration. After architecture modeling to comprehensively describe the SoS, it is essential to transform the models for SoS mission simulation to achieve the virtual verification and validation in MBSE (Model-Based System Engineering). With the analysis of behavior modeling, two methods are introduced. Driving the entities in mission simulation system directly by the state machine models in SoS architecture after the interface definition is a proven method. Through the format conversion of the SoS architecture outputs, the operational/system state diagrams can be transformed to the corresponding organizations/systems behavior models in the mission simulation system. A sample case is provided to illustrate the continuous behavior modeling by format conversion in an air-to-surface attack mission. Compared to the traditional manual behavior modeling, the format conversion method leaves out the repeated behavior modeling and saves the corresponding working load.KeywordsBehavior modelingSystem of systemsModel transformation

This paper proposes a novel dynamic slicing technique for object oriented concurrent programs. We introduce the notion of object oriented concurrent program dependence graph (OOCPDG). Our dynamic slicing technique uses OOCPDG as the intermediate representation and is based on marking and unmarking the dependence edges as and when the dependences arise and cease at runtime. Our approach eliminates the use of trace files and is more efficient than existing algorithms. Besides, it encompasses different aspects of object oriented programming paradigm viz. inheritance, polymorphism from the slicing arena. It can handle dynamically created object based processes. It can also handle process interactions through shared memory and message passing. The updating to the intermediate representation is truly concurrent. Multiple processors execute different object based processes concurrently and require special handling. We also report a dynamic slicing tool called CDSOOCP (concurrent dynamic sheer for object oriented concurrent programs) which implements our dynamic slicing technique.

The recent trend in the war fields on the globe may be characterized by the network-centric warfare, which would, in turn, make the concept of weapon systems be changed. To this end, the concept of system of systems (SoS) has been introduced in literature. An SoS is a collection of multiple systems, each of which is an independent system and can be interoperable with each other. Thus, in defense domain each SoS is a big weapon system as a whole operated in actual environment and each element of it is also an independent smaller weapon system, but they should be interoperable via network among each other. The safety results studied for each elementary system alone may not be fully applicable to the whole SoS. As such, the objective of this paper is to study how to make the SoS safety requirements be distributed down over the interoperable elementary systems. Since handling the interoperability requires a technique of systems architecture, a standard method called the DoD Architectural Framework (DoDAF) has been used here to derive a solution. Using DoDAF, the safety requirements were first analyzed in the operability environment. The results were then studied to be included in an integrated model of both the systems design and safety processes. A further study of present paper would facilitate ensuring safety in the development of SoS weapon systems in practice.

Systems of Systems (SoS) modeling is becoming increasingly important in both civilian and military systems. The Department of Defense (DoD) Defense Acquisition Guidebook, [1] defines a SoS as a “set or arrangement of systems that results when independent and useful systems are integrated into a larger system that delivers unique capabilities.” Organizations are changing their emphasis from “We need a new system” to “We need to achieve a specific outcome.” As these outcomes become more complex and the associated systems more complex, the management, modeling and simulation of these SoS becomes equally challenging. Often, the SoS is modeled in all its complexity, often at a single level of abstraction or level of detail. Instead of a “megamodel” approach, a standards-based “model of models” approach is what is necessary. This approach will use the Object Management Group (OMG) Unified Profile for DoDAF and MODAF (UPDM) for modeling enterprise architectures from capabilities to detailed components, and the Reusable Asset Specification (RAS) for defining reusable assets. Combining UPDM and RAS provides a Model of Models approach with the main model specifying assets in various levels of details. The models specified by these assets can be referenced when detailed analysis is required, or hidden when a SoS viewpoint is required, allowing the analyst to see the forest through the trees. The paper will also include an assessment of the applicability and effectiveness of this approach. The International Conference on Systems Engineering (INCOSE) System of Systems Working Group (SoSWG) has collected a set of “Pain Points on SoS” from a variety of international sources. This paper will review these pain points and discuss how the application of a Model of Model approach, combined with standards-based modeling tools and a reusable assets approach can help to alleviate some of the pain currently being felt by SoS architects and managers. Hopefully, this response to their SOS will deliver some much-needed assistance.

Systems of Systems (SoS) are complex systems composed of managerially and operationally independent constituent systems (CS). Smart cities are examples of SoS. However, these types of systems impose challenges to traditional software architecture such as highly evolutionary architecture due to the evolution of individual CS and emergent behaviors that results from the interoperability of CS. Executable Models (ExM) are a class of models that can be executed and that can assist on architectural design of SoS. By using them, architects can predict the SoS structure and behavior by visualizing and simulating the SoS still at design-time. On the other hand, as any other emergent technologies, it suffers with absent scientific evidences of its benefits, mainly in industrial context. The main contribution of this master thesis project intends to be the presentation of evidences about the use of ExM to solve problems in the SoS software architecture design. For achieving such purpose, this project is structured in well-defined steps: (i) a systematic mapping study, (ii) elaboration of a conceptual map derived from the mapping study, (iii) a survey to obtain perceptions from software engineering professionals on the use of ExM in the context of engineering simple systems and (iv) a new survey expanding the previous study and to obtain perceptions from software engineering professionals on the use of ExM in the context of architectural design of SoS. Preliminary results reveal that ExM have been reported in diverse SoS domains, offering a dynamic and interactive view to the SoS. We also found that software engineering professionals see ExM as suitable solution for dealing with complex and critical systems as SoS.

The term System of Systems (SoS) is used to describe the coming together of independent systems, collaborating to achieve a new or higher purpose. However, the SoS concept is often misunderstood within operational environments, providing challenges towards the secure design and operation of SoSs. Limitations in existing literature indicates a need for discovery towards identifying a combination of concepts, models, and techniques suitable for assessing SoS security risk and related human factor concerns for SoS Requirements Engineering. In this article, we present OASoSIS, representing an information security risk assessment and modelling process to assist risk-based decision making in SoS Requirements Engineering. A characterisation process is introduced to capture the SoS context, supporting a SoS security risk assessment process that extends OCTAVE Allegro towards a SoS context. Resulting risk data provides a focused means to assess and model the SoS information security risk and related human factors, integrating tool-support using CAIRIS. A medical evacuation SoS case study scenario was used to test, illustrate, and validate the alignment of concepts, models, and techniques for assessing SoS information security risks with OASoSIS, where findings provide a positive basis for future work.

In a system of systems (SoS) consisting of heterogeneous independently operable systems, effective communication among the systems is essential. These independent systems need to understand each other through effective communication in or order for them to establish a SoS. Thus, there is a need for a common language which wraps the data that is sent and received from a system within a SoS. This paper presents and extends the application of extensible markup language (XML) to represent data communicated among systems without underlying differences in hardware/software of the individual systems. Moreover, since the operation of each system is asynchronous in nature, the entire SoS can be considered as an event driven system. This paper extends an XML based SoS simulation framework to simulate a robust threat detection and integration problem. The DEVSJAVA software is used as the discrete event simulator. Finally, XML based encapsulation is created in the DEVSJAVA environment to create the common language for the heterogeneous systems in a SoS.

A System of Systems (SoS) is a term used to describe independent systems converging for a purpose that could only be carried out through this interdependent collaboration. Many examples of SoSs exist, but the term has become a source of confusion across domains. Moreover, there are few illustrative SoS examples demonstrating their initial classification and structure. While there are many approaches for engineering of systems, less exist for SoS engineering. More specifically, there is a research gap towards approaches addressing SoS security risk assessment for engineering and operational needs, with a need for tool-support to assist modelling and visualising security risk and requirements in an interconnected SoS. From this, security requirements can provide a systematic means to identify constraints and related risks of the SoS, mitigated by human-user and system requirements. This work investigates specific challenges and current approaches for SoS security and risk, and aims to identify the alignment of SoS factors and concepts suitable for eliciting, analysing, validating risks with use of a tool-support for assessing security risk in the SoS context.

A System-of-Systems (SoS) is a collection of distributed independent individual systems that interact with one another to achieve an SoS capability requirement that cannot be achieved by individual systems alone (in contrast, in a monolithic system, hardware or software components are integrated to form a single entity). Interdependency between SoS systems, while enabling new capability, also means that failures can cascade throughout the SoS, creating development delays or additional system failures. Here we develop a method based on Bayesian networks to evaluate the resilience of SoS design alternatives to failures during operations. We propose a conditional resilience metric that measures each constituent system's contribution to overall SoS resilience, and a resilience pattern that shows how SoS performance degrades as systems fail. SoS resilience is determined by both the SoS architecture and the constituent system reliability. In a simple example based on the Littoral Combat Ship SoS, we determine the two most critical systems using the conditional resilience metric. Adding a communications link between these two systems increases the resilience, resulting in higher expected performance and slower expected performance degradation as a result of system failure. The conditional resilience and resilience pattern can be used by designers and other decision makers to identify SoS architectures and systems that increase SoS resilience to failure.

Systems-of-Systems (SoS) is a set of independent software-intensive systems intended to support critical domains, such as emergency and crisis response systems and health. As such, SoS should exhibit robust behaviors and guarantee that the entire system is continuously available, not failing and leaving its users helpless. However, the SoS inherent dynamic architecture can potentially affect the availability of the functionalities being offered by the SoS. Hence, it is prominently important to anticipate, at design-time, the degree of availability an SoS can offer and provide mechanisms to reinforce the availability provided by it. Usually, software architects use static models to predict quality attributes in software architectures. However, these models are not well-succeeded to deal with the dynamic nature of the SoS architectures. The main contribution of this paper is thus presenting emerging results on the establishment of a simulation-based approach for empirically predicting the availability of SoS software architectures at design time. A Flood Monitoring SoS was used as the experimental platform. Preliminary results indicate that, specifically for the context of our study, the nature of availability in SoS architectures was not only influenced by the availability of the SoS constituents, but also by the SoS topology.

When independent systems come together as a System of Systems (SoS) to achieve a new purpose, dealing with requirements conflicts across systems becomes a challenge. Moreover, assessing and modelling security risk for independent systems and the SoS as a whole is challenged by a gap in related research and approaches within the SoSs domain. In this paper, we present an approach for bridging SoS and Requirements Engineering by identifying aligning SoSs concepts to assess and model security risk and requirements. We introduce our OASoSIS approach modifying OCTAVE Allegro for SoSs using CAIRIS (Computer Aided Integration of Requirements and Information Security) with a medical evacuation (MEDEVAC) SoS exemplar for Security Requirements Engineering tool-support.

ContextIn contrast to traditional software systems that are mostly created from scratch, current software systems are engineered as a junction of systems already in operation. Examples can be found in domains, such as smart cities, crisis and emergency, IoT, big data, industry 4.0, and connected health systems. Most of them can be considered systems-of-systems (SoS), since they refer to alliances of operational and managerial independent software-intensive systems, which are sometimes distributed over different environments. Therefore, SoS software architectures must be dynamic, evolve over time, and support the execution of emergent behaviors to accomplish SoS missions. They must be also designed to enable the connection of heterogeneous systems, making possible their interoperation, communication, coordination, cooperation, and collaboration, most of the times, in a seamless way. Similar challenges have been addressed by using software mediators as architectural entities. However, the application of mediators in SoS has not been properly explored.GoalThis article introduces MediArch, a layered architecture that considers mediators as first-class software entities to be used in the construction of SoS architectures. Our objective is to present evidence about how MediArch’s can support the construction of SoS architectures.MethodsThe following four steps were conducted to define MediArch: (1) identification of mediation requirements to allow SoS properties; (2) establishment and categorization of twelve types of mediators, for enabling capabilities of communication and control of constituent systems interactions and conversion of heterogeneous messages exchanged through a mediation infrastructure; (3) specification of duties, behaviors, assumptions, and guarantees of mediators; and (4) organization of MediArch in three layers, namely, the constituents & consumer systems layer; the communication, conversion, & coordination layer; and the control layer. This architecture was used as the backbone for the software architectures of two SoS in different domains, namely, flood monitoring system-of-systems (FMSoS), and health-care supportive home system-of-systems (HSH-SoS), for providing evidence on how MediArch supports the architecting process of SoS.ResultsMediArch (1) supports the integration of independent constituent systems, (2) provides strategies to manage emergent behaviors, (3) defines different schemes of control authorities, (4) offers elements to support SoS evolution, and (5) promotes the resilience and adaptability of SoS architectures.ConclusionsAlthough MediArch contributes to the establishment of SoS architectures, some challenges related to performance, resource consumption, security, safety, and non-disruptive reconfigurations must still be overcome.

Software architecture is a software system’s earliest set of design decisions that are critical for the quality of the system desired by the stakeholders. The architecture makes it easier to reason about and manage change during different phases of complex software life cycle. The modeling of software architecture for System of Systems (SoS) is a challenging task because of a system’s complexity arising from an integration of heterogeneous, distributed, managerially and operationally independent systems collaborating to achieve global missions. SoS is essentially dynamic and evolutionary by design requiring suitable architectural patterns to deal with runtime volatility. Service-oriented architecture offers several architectural features to these complex systems; these include, interoperability, loose coupling, abstraction and the provision of dynamic services based on standard interfaces and protocols. There is some research work available that provides critical analysis of current software architecture modeling approaches for SoS. However, none of them outlines the important characteristics of SoS or provides detailed analysis of current service-oriented architecture modeling approaches to model those characteristics. This article addresses this research gap and provides a taxonomy of software architecture modeling approaches, comparing and contrasting them using criteria critical for realization of SoS. Additionally, research gaps are identified, and future directions are outlined for building software architecture for SoS to model and reason about architecture quality in a more efficient way in service-oriented paradigm.

This paper presents a context-sensitive dynamic slicing technique for concurrent AOPs having multiple threads. To effectively represent the concurrent AOP, we propose an intermediate graph called Multithreaded Aspect-Oriented Dependence Graph (MAODG). Based on this intermediate representation, we design a precise and accurate dynamic slicing algorithm for concurrent AOPs. This algorithm takes the MAODG of the concurrent AOP and a slicing criterion as input and computes the dynamic slice for the given concurrent AOP.