Jan Carlson

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Continuous integration support in modeling tools

Continuous Integration (CI) and Model-Based Development (MBD) have both been hailed as practices ... more Continuous Integration (CI) and Model-Based Development (MBD) have both been hailed as practices that improve the productivity of so ware development. eir combination has the potential to boost productivity even more. e goal of our research is to identify impediments to realizing this combination in industrial collaborative modeling practices. In this paper, we examine certain speci c features of modeling tools that, due to their immaturity, may represent impediments to combining CI and MBD. To this end, we identify features of modeling tools that are relevant to enabling CI practices in MBD processes and we review modeling tools with respect to their level of support for each of these features.

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Software Engineering for Smart Cyber-Physical Systems -- Towards a Research Agenda

ACM SIGSOFT Software Engineering Notes, 2015

Cyber-Physical Systems (CPS) are large interconnected softwareintensive systems that influence, b... more Cyber-Physical Systems (CPS) are large interconnected softwareintensive systems that influence, by sensing and actuating, the physical world. Examples are traffic management and power grids. One of the trends we observe is the need to endow such systems with the "smart" capabilities, typically in the form of selfawareness and self-adaptation, along with the traditional qualities of safety and dependability. These requirements combined with specifics of the domain of smart CPS -- such as large scale, the role of end-users, uncertainty, and open-endedness -- render traditional software engineering (SE) techniques not directly applicable; making systematic SE of smart CPS a challenging task. This paper reports on the results of the First International Workshop on Software Engineering of Smart Cyber-Physical Systems (SEsCPS 2015), where participants discussed characteristics, challenges and opportunities of SE for smart CPS, with the aim to outline an agenda for future researc...

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Impediments to Introducing Continuous Integration for Model-Based Development in Industry

Model-based development and continuous integration each separately are methods to improve the pro... more Model-based development and continuous integration each separately are methods to improve the productivity of development of complex modern software systems. We investigate industrial adoption of these two phenomena in combination, i.e., applying continuous integration practices in model-based development projects. Through semi-structured interviews, eleven engineers at three companies with different modelling practices share their views on perceived and experienced impediments to this adoption. We find some cases in which this introduction is undesired and expected to not be beneficial. For other cases, we find and categorize several impediments and discuss how they are dealt with in industrial practice. Model synchronization and tool interoperability are found the most challenging to overcome and the ways in which they are circumvented in practice are detrimental for introducing continuous integration.

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Formal Semantics of the ProCom Real-Time Component Model

ProCom is a new component model for real-time and embedded systems, targeting the domains of vehi... more ProCom is a new component model for real-time and embedded systems, targeting the domains of vehicular and telecommunication systems. In this paper, we describe how the architectural elements of the ProCom component model have been given a formal semantics. The semantics is given in a small but powerful finite state machine formalism, with notions of urgency, timing, and priorities. By defining the semantics in this way, we (i) provide a rigorous and compact description of the modeling elements of ProCom, (ii) set the ground for formal analysis using other formalisms, and (iii) provide an intuitive and useful description for both practitioners and researchers. To illustrate the approach, we exemplify with a number of particularly interesting cases, ranging from ports and services to components and component hierarchies.

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Integration of Extra-Functional Properties in Component Models

Springer eBooks, 2009

Management of extra-functional properties in component models is one of the main challenges in th... more Management of extra-functional properties in component models is one of the main challenges in the component-based software engineering community. Still, the starting point in their management, namely their speci cation in a context of component models is not addressed in a systematic way. Extrafunctional properties can be expressed as attributes (or combinations of them) of components, or of a system, but also as attributes of other elements, such as interfaces and connectors. Attributes can be de ned as estimations, or can be measured, or modelled; this means that an attribute can be expressed through multiple values valid under different conditions. This paper addresses how this diversity in attribute speci cations and their relations to component model can be expressed, by proposing a model for attribute speci cations and their integrations in component models. A format for attribute speci cation is proposed, discussed and analyzed, and the approach is exempli ed through its integration both in the ProCom component model and its integrated development environment. more complex. The problem already appears in the speci cations of attributes. While component models precisely de ne interfaces as a means of functional speci cation, speci cations of attributes in relation to component speci cation is either not de ned, or unclear. Is an attribute a property of a component or the result of interaction between components, or maybe the result of performing a function that is part of the component interface, or the result of combining a component and its environment? So far these questions have not been addressed in a systematic way. This paper addresses the question of attribute speci cation in component models. The speci cation of attributes has several aspects that we discuss and demonstrate on a component model.

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Progress Component Model Reference Manual - version 0.5

This report describes the component model developed within PROGRESS. In addition to defining the ... more

Assured Cloud Platforms for Industrial Cyber-Physical Systems: The ACICS Approach

With the emergence of “Industry 4.0”, the integration of cloud technologies and industrial cyber-... more With the emergence of “Industry 4.0”, the integration of cloud technologies and industrial cyber-physical systems becomes increasingly important to boost productivity. The industrial cyber-physical systems infrastructures and their fusion with the cloud lead to massive amounts of data acquired for controlling particular processes, but also for supporting decision-making. Although cloud-assisted systems are increasingly important in many domains, and ensuring their dependability is crucial, existing platforms do not provide satisfactory support to meet the dependability demands of industrial applications. The overall goal of the ACICS project is to provide models, methods and tools that facilitate a substantial increase of dependability of cloud-based platforms for industrial cyber-physical applications, with respect to consistency, security and interoperability of data, timing predictability of using shared virtual resources, together with a framework of guaranteeing quality-of-service enforcement by formal analysis and verification. In this paper, we present the main conceptual ideas behind the ACICS approach.

Component-based development of embedded systems with GPUs

Journal of Systems and Software, Mar 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Optimized Realization of Software Components with Flexible OpenCL Functionality

Today, the newly available embedded boards with GPUs provide a solution to satisfy the ever-incre... more Today, the newly available embedded boards with GPUs provide a solution to satisfy the ever-increasing requirements of modern embedded systems. Component-based development is a well-known paradigm used to develop embedded systems. However, this paradigm lacks GPU support to address the specifics of these new boards. This leads to components that typically have reduced reusability, poor maintainability and portability. One way to tackle the existing shortcomings is through flexible components, i.e., platform-agnostic components that, at design time, offer the possibility to be executed either on CPU or GPU. The current realization of flexible components, i.e., as regular components with functionality tailored for the selected hardware, introduces additional overheads such as component communication overhead. In order to tackle the introduced overheads, our solution groups connected flexible components under a flexible group that conceptually behaves as a component. We introduce an algorithm to identify the existing groups in a given component-based system and the generation rules that automatically realizes groups as regular components. To evaluate the feasibility of the new concept, the flexible group is implemented using a state-of-the-practice component model (i.e., Rubus) and examined through the vision system of an underwater robot.

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Connecting ProCom and REMES

When component-based development is applied in the domain of distributed embedded systems, where ... more When component-based development is applied in the domain of distributed embedded systems, where applications are often safety-critical and subject to real-time constraints, it is of significant importance that reliable predictions of functional and extra-functional properties can be derived at design-time. Preferably, analysis should be performed in early development phases, where the cost of modifying the design is lower. Centered on an example application from the automation domain, we show how a component model specifically intended for embedded systems can be combined with a language for high-level formal behavior modeling. This allows modeling the behavior of individual components, in terms of functionality, timing and resource usage. In turn, this permits analysis of system level properties, while also supporting reuse of behavioral models when components are reused.

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Allocation Optimization for Component-Based Embedded Systems with GPUs

Platforms equipped with GPU processors help mitigating the ever-increasing computational demands ... more Platforms equipped with GPU processors help mitigating the ever-increasing computational demands of modern embedded systems. Such systems can be specifically developed by using component-based development thanks to the concept of flexible components. Through this concept, a component can be transparently executed either on a CPU or a GPU. However, this flexibility complicates the allocation process, i.e., it is more difficult to know where to allocate the components to best utilize the limited resources of the platform. In this work, we address this problem by providing an optimization model for componentbased embedded systems executing on both CPU and GPU. The model addresses important optimization goals, characteristic to the embedded system domain, such as memory usage, energy usage and execution time. A novelty of this work is the formal description of the optimization model, which supports the usage of mixed integer nonlinear programming to compute optimal allocation schemes. To examine the feasibility of the proposed method, we apply the optimization model on a vision system constructed using the industrial Rubus component model.

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The GRADE Decision Canvas for Classification and Reflection on Architecture Decisions

This paper introduces a decision canvas for capturing architecture decisions in software and syst... more This paper introduces a decision canvas for capturing architecture decisions in software and systems engineering. The canvas leverages a dedicated taxonomy, denoted GRADE, meant for establishing the basics of the vocabulary for assessing and choosing architectural assets in the development of software-intensive systems. The canvas serves as a template for practitioners to discuss and document architecture decisions, i.e., capture, understand and communicate decisions among decision-makers and to others. It also serves as a way to reflect on past decision-making activities devoted to both tentative and concluding decisions in the development of software-intensive systems. The canvas has been assessed by means of preliminary internal and external evaluations with four scenarios. The results are promising as the canvas fulfills its intended objectives while satisfying most of the needs of the subjects participating in the evaluation.

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Automatic Synthesis and Adaption of Gray-Box Components for Embedded Systems - Reuse vs. Optimization

Component-based development of embedded systems has been suggested as a means to increase develop... more Component-based development of embedded systems has been suggested as a means to increase development efficiency by, for example, facilitating reuse. However, the specifics of the embedded systems domain also raise some particular difficulties when applying this approach. For example, when glue code is automatically produced from an architectural specification, a systematic approach where fully reusable code is generated for all entities in the system, can lead to unaffordable overhead in embedded systems with severe resource limitations and temporal constraints. If, on the other hand, highly optimized code is produced by taking advantage of the specific context in which each component is used, then the generated code is not reusable in other contexts, and the potential benefits of component-based development are not fully exploited. In this paper, we present a component-based framework that permits a more detailed trade-off between optimization and reusability, by automating the integration of components for which the software designer can specify the desired reuse potential. Depending on this specification, the integration code is either reused and adapted, or completely optimized.

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Towards evidence‐based decision‐making for identification and usage of assets in composite software: A research roadmap

Journal of software, Mar 19, 2021

Software engineering is decision intensive. Evidence-based software engineering is suggested for ... more Software engineering is decision intensive. Evidence-based software engineering is suggested for decision-making concerning the use of methods and technologies when developing software. Software development often includes the reuse of software assets, for example, open-source components. Which components to use have implications on the quality of the software (e.g., maintainability). Thus, research is needed to support decision-making for composite software. This paper presents a roadmap for research required to support evidence-based decision-making for choosing and integrating assets in composite software systems. The roadmap is developed as an output from a 5-year project in the area, including researchers from three different organizations. The roadmap is developed in an iterative process and is based on (1) systematic literature reviews of the area; (2) investigations of the state of practice, including a case survey and a survey; and (3) development and evaluation of solutions for asset identification and selection. The research activities resulted in identifying 11 areas in need of research. The areas are grouped into two categories: areas enabling evidence-based decision-making and those related to supporting the decision-making. The roadmap outlines research needs in these 11 areas. The research challenges and research directions presented in this roadmap are key areas for further research to support evidence-based decision-making for composite software.

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Tool-Supported Safety-Relevant Component Reuse: From Specification to Argumentation

Lecture Notes in Computer Science, 2018

Contracts are envisaged to support compositional verification of a system as well as reuse and in... more Contracts are envisaged to support compositional verification of a system as well as reuse and independent development of their implementations. But reuse of safety-relevant components in safety-critical systems needs to cover more than just the implementations. As many safety-relevant artefacts related to the component as possible should be reused together with the implementation to assist the integrator in assuring that the system they are developing is acceptably safe. Furthermore, the reused assurance information related to the contracts should be structured clearly to communicate the confidence in the component. In this work we present a tool-supported methodology for contract-driven assurance and reuse. We define the variability on the contract level in the scope of a trace-based approach to contract-based design. With awareness of the hierarchical nature of systems subject to compositional verification, we propose assurance patterns for arguing confidence in satisfaction of requirements and contracts. We present an implementation extending the AMASS platform to support automated instantiation of the proposed patterns, and evaluate its adequacy for assurance and reuse in a real-world case study.

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Developing CPU-GPU Embedded Systems Using Platform-Agnostic Components

Nowadays, there are many embedded systems with different architectures that have incorporated GPU... more Nowadays, there are many embedded systems with different architectures that have incorporated GPUs. However, it is difficult to develop CPU-GPU embedded systems using component-based development (CBD), since existing CBD approaches have no support for GPU development. In this context, when targeting a particular CPU-GPU platform, the component developer is forced to construct hardware-specific components, which are problematic to (re-)use in different contexts. Moreover, hard-coding specific GPU-usage characteristics (e.g., the number of utilized GPU threads) inside the component is not possible without making detailed assumptions about the system in which the component is used, which conflicts with separation-of-concerns CBD principle.The paper presents a solution to allow component-based development of platform-agnostic CPU-GPU embedded systems through: i) high-level API, ii) adapters, and iii) code template. The API abstracts the specifics of the different platforms, while the adapters externalize hardware-specific activities outside components. We also raise the decision regarding the GPU-usage specifications, from the component to the system level. Furthermore, to minimize the development effort, we provide a code template that contains ready-made code fragments required for GPU development. As a case study, we examine the feasibility of our solution applied on a component-based vision system of an underwater robot.

Towards the architecture of a decision support ecosystem for system component selection

2017 Annual IEEE International Systems Conference (SysCon), Apr 1, 2017

When developing complex software-intensive systems, it is nowadays common practice to base the so... more When developing complex software-intensive systems, it is nowadays common practice to base the solution partly on existing software components. Selecting which components to use becomes a critical decision in development, but it is currently not well supported through methods and tools. This paper discusses how a decision support system for this problem could benefit from a software ecosystem approach, where participants share knowledge across organizations both through reuse of analysis models, and through partially disclosed past decision cases. We show how the ecosystem architecture becomes fundamental to deal with efficient knowledge sharing, while respecting constraints on integrity of intellectual property. A concrete architecture proposal is outlined, which is a web-based distributed system-of-systems. Experiences of a proof-of-concept implementation are also described.

A Method to Generate Reusable Safety Case Fragments from Compositional Safety Analysis

Springer eBooks, 2014

Safety-critical systems usually need to be accompanied by an explained and well-founded body of e... more Safety-critical systems usually need to be accompanied by an explained and well-founded body of evidence to show that the system is acceptably safe. While reuse within such systems covers mainly code, reusing accompanying safety artefacts is limited due to a wide range of context dependencies that need to be satisfied for safety evidence to be valid in a different context. Currently the most commonly used approaches that facilitate reuse lack support for reuse of safety artefacts. To facilitate reuse of safety artefacts we provide a method to generate reusable safety case argument-fragments that include supporting evidence related to safety analysis. The generation is performed from safety contracts that capture safety-relevant behaviour of components within assumption/guarantee pairs backed up by the supporting evidence. We illustrate our approach by applying it to an airplane wheel braking system example.

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ProCom : Formal Semantics

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Extending the Rubus Component Model with GPU-Aware Components

To support the complex functionality expected of modern embedded systems, the trend is to supplem... more To support the complex functionality expected of modern embedded systems, the trend is to supplement CPUs with Graphical Processing Units (GPUs), thus creating heterogeneous embedded systems. However, taking full advantage of GPUs increases the complexity of the development and requires dedicated support, and no such support exists in the component models currently available. The only solution today is to completely encapsulate all GPU-specific information and operations within the components, which increases the communication overhead and reduces component reusability, thus significantly limiting the applicability of component-based development to heterogeneous embedded systems. In this paper, we propose to extend Rubus, an industrial component model for embedded systems, with dedicated support for GPUs. We introduce new constructs, including GPU ports and automatically generated adapters to facilitate seamless component communication over the heterogeneous processing units, regardless of whether the components use the CPU, GPU, or both. A running example is used for the problem description, the proposed extension, and to evaluate our solution.

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