Design and management of image processing pipelines within CPS: Acquired experience towards the end of the FitOptiVis ECSEL Project

Cyber-Physical Systems (CPSs) are dynamic and reactive systems interacting with processes, environment and, sometimes, humans. They are often distributed with sensors and actuators, characterized for being smart, adaptive, predictive and react in real-time. Indeed, image- and video-processing pipelines are a prime source for environmental information for systems allowing them to take better decisions according to what they see. Therefore, in FitOptiVis, we are developing novel methods and tools to integrate complex image- and video-processing pipelines. FitOptiVis aims to deliver a reference architecture for describing and optimizing quality and resource management for imaging and video pipelines in CPSs both at design- and run-time. The architecture is concretized in low-power, high-performance, smart components, and in methods and tools for combined design-time and run-time multi-objective optimization and adaptation within system and environment constraints.     

An architecture-driven software mobility framework

Software architecture has been shown to provide an appropriate level of granularity for assessing a software system’s quality attributes (e.g., performance and dependability). Similarly, previous research has adopted an architecture-centric approach to reasoning about and managing the run-time adaptation of software systems. For mobile and pervasive software systems, which are known to be innately dynamic and unpredictable, the ability to assess a system’s quality attributes and manage its dynamic run-time behavior is especially important. In the past, researchers have argued that a software architecture-based approach can be instrumental in facilitating mobile computing. In this paper, we present an integrated architecture-driven framework for modeling, analysis, implementation, deployment, and run-time migration of software systems executing on distributed, mobile, heterogeneous computing platforms. In particular, we describe the framework’s support for dealing with the challenges posed by both logical and physical mobility. We also provide an overview of our experience with applying the framework to a family of distributed mobile robotics systems. This experience has verified our envisioned benefits of the approach, and has helped us to identify several avenues of future work.     

CADSE: communication aware design space exploration for efficient run-time MPSoC management

Real-time multi-media applications are increasingly mapped on modern embedded systems based on multiprocessor systems-on-chip (MPSoC). Tasks of the applications need to be mapped on the MPSoC resources efficiently in order to satisfy their performance constraints. Exploring all the possible mappings, i.e., tasks to resources combinations exhaustively may take days or weeks. Additionally, the exploration is performed at design-time, which cannot handle dynamism in applications and resources’ status. A runtime mapping technique can cater for the dynamism but cannot guarantee for strict timing deadlines due to large computations involved at run-time. Thus, an approach performing feasible compute intensive exploration at design-time and using the explored results at run-time is required. This paper presents a solution in the same direction. Communicationaware design space exploration (CADSE) techniques have been proposed to explore different mapping options to be selected at run-time subject to desired performance and available MPSoC resources. Experiments show that the proposed techniques for exploration are faster over an exhaustive exploration and provides almost the same quality of results.     

Architecture for embedded open software ecosystems

Software is prevalent in embedded products and may be critical for the success of the products, but manufacturers may view software as a necessary evil rather than as a key strategic opportunity and business differentiator. One of the reasons for this can be extensive supplier and subcontractor relationships and the cost, effort or unpredictability of the deliverables from the subcontractors are experienced as a major problem.The paper proposes open software ecosystem as an alternative approach to develop software for embedded systems, and elaborates on the necessary quality attributes of an embedded platform underlying such an ecosystem. The paper then defines a reference architecture consisting of 17 key decisions together with four architectural patterns, and provides the rationale why they are essential for an open software ecosystem platform for embedded systems in general and automotive systems in particular.The reference architecture is validated through a prototypical platform implementation in an industrial setting, providing a deeper understanding of how the architecture could be realised in the automotive domain.Four potential existing platforms, all targeted at the embedded domain (Android, OKL4, AUTOSAR and Robocop), are evaluated against the identified quality attributes to see how they could serve as a basis for an open software ecosystem platform with the conclusion that while none of them is a perfect fit they all have fundamental mechanisms necessary for an open software ecosystem approach.     

NCSWT: An integrated modeling and simulation tool for networked control systems

Networked Control Systems (NCS) are becoming increasingly ubiquitous in a growing number of applications, such as groups of unmanned aerial vehicles and industrial control systems. The evaluation of NCS properties such as stability and performance is very important given that these systems are typically deployed in critical settings. This paper presents the Networked Control Systems Wind Tunnel (NCSWT), an integrated modeling and simulation tool for the evaluation of Networked Control Systems (NCS). NCSWT integrates Matlab/Simulink and ns-2 for modeling and simulation of NCS using the High Level Architecture (HLA) standard. The tool is composed of two parts, the design-time models and the run-time components. The design-time models use Model Integrated Computing (MIC) to define HLA-based model constructs such as federates representing the simulators and interactions representing the communication between the simulators. MIC techniques facilitate the modeling and design of complex systems by using abstractions defined in domain-specific modeling languages (DSMLs) to describe the systems. The design-time models represent the control system dynamics and networking system behaviors in order to facilitate the run-time simulation of a NCS. The run-time components represent the main software components and interfaces for the actual realization of a NCS simulation using the HLA framework. Our implementation of the NCSWT based on HLA guarantees accurate time synchronization and data communication. Two case studies are presented to demonstrate the capabilities of the tool as well as evaluate the impact of network effects on NCS.     

Scenario-based run-time adaptive MPSoC systems

The ever-increasing performance demand of modern embedded applications drives the development of multi-processor system-on-chip (MPSoC) systems in the embedded domain. Today’s MPSoC-based products increasingly have to deal with multiple application execution scenarios which may change dynamically at run time. To improve the system performance, a state-of-the-art solution is to dynamically adapting the allocation of system resources at run time for each execution scenario based on pre-determined resource schemes that have been optimized at design time. However, such approaches will not work well for MPSoC systems that have a large number of execution scenarios and/or frequent run-time variations in execution scenario behavior. In this work, we therefore propose a scalable run-time self-adaptive framework for MPSoC systems that addresses these problems, thereby considerably improving the system efficiency.     

System-specific static code analyses: a case study in the complex embedded systems domain

In this paper, we are exploring the approach to utilize system-specific static analyses of code with the goal to improve software quality for specific software systems. Specialized analyses, tailored for a particular system, make it possible to take advantage of system/domain knowledge that is not available to more generic analyses. Furthermore, analyses can be selected and/or developed in order to best meet the challenges and specific issues of the system at hand. As a result, such analyses can be used as a complement to more generic code analysis tools because they are likely to have a better impact on (business) concerns such as improving certain software quality attributes and reducing certain classes of failures. We present a case study of a large, industrial embedded system, giving examples of what kinds of analyses could be realized and demonstrate the feasibility of implementing such analyses. We synthesize lessons learned based on our case study and provide recommendations on how to realize system-specific analyses and how to get them adopted by industry.     

Knowledge based quality-driven architecture design and evaluation

Modelling and evaluating quality properties of software is of high importance, especially when our every day life depends on the quality of services produced by systems and devices embedded into our surroundings. This paper contributes to the body of research in quality and model driven software engineering. It does so by introducing; (1) a quality aware software architecting approach and (2) a supporting tool chain. The novel approach with supporting tools enables the systematic development of high quality software by merging benefits of knowledge modelling and management, and model driven architecture design enhanced with domain-specific quality attributes. The whole design flow of software engineering is semi-automatic; specifying quality requirements, transforming quality requirements to architecture design, representing quality properties in architectural models, predicting quality fulfilment from architectural models, and finally, measuring quality aspects from implemented source code. The semi-automatic design flow is exemplified by the ongoing development of a secure middleware for peer-to-peer embedded systems.     

Embedded software engineering: the state of the practice

Technologies for the development of embedded systems should address specific constraints such as hard timing constraints, limited memory and power use, predefined hardware platform technology, and hardware costs. Existing development technologies don't address their specific impact on, or necessary customization for, the embedded domain. Nor do these technologies give developers any indication of how to apply them to specific areas in this domain, for example, automotive systems, telecommunications, or consumer electronics. Consequently, tailoring a technology for a specific use is difficult. Furthermore, the embedded domain is driven by reliability factors, cost factors, and time to market. So, this embedded domain needs specifically targeted development technologies. An inventory of eight European companies reveals what tools developers of embedded-systems software are and aren't using, and why. The need exists for more specific, yet flexible, tools.     

A formal approach to adaptive software: continuous assurance of non-functional requirements

Modern software systems are increasingly requested to be adaptive to changes in the environment in which they are embedded. Moreover, adaptation often needs to be performed automatically, through self-managed reactions enacted by the application at run time. Off-line, human-driven changes should be requested only if self-adaptation cannot be achieved successfully. To support this kind of autonomic behavior, software systems must be empowered by a rich run-time support that can monitor the relevant phenomena of the surrounding environment to detect changes, analyze the data collected to understand the possible consequences of changes, reason about the ability of the application to continue to provide the required service, and finally react if an adaptation is needed. This paper focuses on non-functional requirements, which constitute an essential component of the quality that modern software systems need to exhibit. Although the proposed approach is quite general, it is mainly exemplified in the paper in the context of service-oriented systems, where the quality of service (QoS) is regulated by contractual obligations between the application provider and its clients. We analyze the case where an application, exported as a service, is built as a composition of other services. Non-functional requirements—such as reliability and performance—heavily depend on the environment in which the application is embedded. Thus changes in the environment may ultimately adversely affect QoS satisfaction. We illustrate an approach and support tools that enable a holistic view of the design and run-time management of adaptive software systems. The approach is based on formal (probabilistic) models that are used at design time to reason about dependability of the application in quantitative terms. Models continue to exist at run time to enable continuous verification and detection of changes that require adaptation.     

嵌入式软件全数字仿真测试环境设计

嵌入式软件所具有的实时性、嵌入性特点,使得仿真测试成为保证嵌入式软件质量的一种重要测试方法.首先分析了当前仿真测试方法现状及存在的问题,然后提出了一种基于宿主机的嵌入式软件全数字仿真测试环境设计方案,用软件来仿真嵌入式软件运行所需的目标机硬件及外部设备,能够在不具备目标硬件系统情况下,进行非干涉、实时的嵌入式软件闭环测试,最后提出了通过建立仿真构件库实现快速建立全数字仿真测试环境的方法.     

Design for Timing Predictability

A large part of safety-critical embedded systems has to satisfy hard real-time constraints. These need sound methods and tools to derive run-time guarantees that are not only reliable but also precise. The achievable precision highly depends on characteristics of the target architecture, the implementation methods and system layers of the software. Trends in hardware and software design run contrary to predictability. This article describes threats to timing predictability of systems, and proposes design principles that support timing predictability. The ultimate goal is to design performant systems with sharp upper and lower bounds on execution times.     

Quality specification and metrication,results from a case-study in a mission-critical software domain

Software quality is of increasing importance in mission-critical embedded software systems. Due to the fast growing complexity and accompanying risks of failures of these systems, software quality needs to be addressed explicitly by software developers, preferably with a systematic method for an optimal implementation of software qualities, such as reliability, time-behavior and usability. At the Centre of Automation of Mission-critical Systems (CAMS) of the Dutch Royal Navy, a new approach has been defined for software developers to improve the way that they deal with software quality in the process of mission-critical systems engineering. The stepwise approach is based on both an international quality standard for software product quality, i.e. ISO9126, and on Multi-Criteria Decision Making techniques, i.e. analytical hierarchy process (AHP). The stepwise approach has been validated in a case study. In particular, the tailoring of the ISO9126 standard toward the specific CAMS development situation, and the applicability of AHP techniques, from the perspective of software developers, has been investigated. The case study is carried out in a representative software development project, i.e. the software for combat management systems (CMS) of warships. Results of the case study show that software developers can explicitly deal with quality on the basis of both the ISO9126 standard and the AHP techniques, respectively regarding the specification, prioritization and metrication of software product quality.     

Periodic timers revisited: The real-time embedded system perspective

Common sense dictates that single-shot timer mechanisms are more suitable for real-time applications than periodic ones, specially in what concerns precision and jitter. Nevertheless, real-time embedded systems are inherently periodic, with tasks whose periods are almost always known at design-time. Therefore a carefully designed periodic timer should be able to incorporate much of the advantages of single-shot timers and yet avoid hardware timers reprogramming, an expensive operation for the limited-resource platforms of typical embedded systems.In this paper, we describe and evaluate two timing mechanisms for embedded systems, one periodic and another single-shot, aiming at comparing them and identifying their strengths and weaknesses. Our experiments have shown that a properly designed periodic timer can usually match, and in some cases even outperform, the single-shot counterpart in terms of precision and interference, thus reestablishing periodic timers as a dependable alternative for real-time embedded systems.     

CRITON: A Hypermedia Design Tool

The WWW has turned into a development and run-time environment for large-scale and complex applications. Such sophisticated applications are being deployed in increasing numbers without having been developed according to appropriate methodologies, tools and quality standards. The reason is not only that the hypermedia industry resists to utilize formal methods, but also that these methods and corresponding tools are very few and of dubious standards. The consequence is that the hypermedia applications being developed are of poor functionality and lack qualities such as modifiability, usability and maintainability. Especially the design phase is one of the phases that lack sufficient support from methods and CASE tools. This paper presents CRITON, a cross platform tool, built to support a hypermedia design method within an integrated environment. CRITON manages all three aspects of hypermedia design: conceptual design, navigational design and graphical user interface design, utilizing well-established theories and practices from software as well as hypermedia engineering. It employs these designs to generate a preliminary, exemplary form of the hypermedia application for the purpose of assessing the designs before the implementation phase.     

Exploring Alternative Software Architecture Designs: A Planning Perspective

Software architecture designs give us blueprints to build systems, enabling key early decisions that can help us achieve a system's functional and quality-attribute requirements. Architectural decisions have far-reaching effects on development in terms of quality, time, and cost. Architects apply technical knowledge and experience to guide their decision making, choosing among multiple design solutions to find a reasonable balance of quality attributes such as performance, modifiability, or security. This is complex and time consuming because qualities can conflict and lead to trade-offs. A trade-off means that the improvement of one quality comes at the cost of degrading another for example, modifiability versus performance. The DesignBots framework supports architects in searching for design alternatives by capturing quality-attribute design concepts into a hierarchical, mixed-initiative planning model. Overall, this work reinforces the argument that Al-based tools can facilitate the design of architectures driven by quality-attribute issues.     

Impact analysis of ERP post-implementation modifications: Design,tool support and evaluation

ERP systems evolve in the post-implementation phase because of changing business requirements. Post-implementation changes are likely to decrease the quality of ERP systems and of the data that they use, which negatively impacts organisational performance. We propose a framework for impact analysis of ERP post-implementation modifications. Our framework allows mapping dependencies among ERP system components and, based on these dependencies, automatically assessing the impact of a proposed change on both the design-time structure and run-time landscape of the system through a novel set of impact metrics. The framework also provides semi-automatic support to safely terminating the running process instances affected by change. The framework is evaluated with expert users in two pseudo-real ERP system implementations.     

Interoperable Run-Time Tools for Distributed Systems—A Case Study

Tools that observe and manipulate the run-time behavior of parallel and distributed systems are essential for developing and maintaining these systems. Sometimes users would even need to use several tools at the same time in order to have a higher functionality at their disposal. Today, tools developed independently by different vendors are, however, not able to interoperate. Interoperability not only allows concurrent use of tools, but also can lead to an added value for the user. A debugger interoperating with a checkpointing system, for example, can provide a debugging environment where the debugged program can be reset to any previous state, thus speeding up cyclic debugging for long running programs.Using this example scenario, we derive requirements that should be met by the tools' software infrastructure in order to enable interoperability. A review of existing infrastructures shows that these requirements are only partially met today. In an ongoing research effort, support for all of the requirements is built into the OMIS compliant on-line monitoring system OCM.     

A component framework for reusing a proprietary computer-aided engineering environment

Nowadays, it is becoming more frequent for engineers to deal with problems and situations that require specific software and the commercially available applications may not result adequate. Because of this, the reuse of software components is becoming a normal practice for improving the productivity of the software programmers, and the quality of the products that they develop. The employment of reusable components presents a number of advantages, such as the reduction in time necessary to develop new software, or the simplification of many computational tasks.There are some proprietary software environments in the engineering domain that are practically de facto standards, since they offer a broad functionality, robustness and constant updating. Therefore, those environments could be ideal candidates to be reusable components when developing new software. An example of this is Matlab, which can be encapsulated, in order to use it as a true reusable component. This will provide the user with efficient tools for designing his/her own applications.Moreover, there is an increasing importance for any software to offer distributed services. To perform this task, it is fundamental to have at one’s disposal reusable components that support Internet-based distributed applications and services development.In the present work, a software component framework that effectively encapsulates Matlab is described. This software allows developers the reuse of Matlab, for both local and distributed applications. To address those issues the .NET technology was employed. The component framework developed can be integrated in the toolbars of software development environments supporting the .NET framework. This facilitates the construction of applications that can reuse the components, since the software developers can use and test them and change their properties in design-time.