International Journal of Software Engineering and Knowledge Engineering

Embedded software is used to control the functions of mechanical and physical devices by dedicated digital signal processor and computers. Nowadays, heterogeneous and collaborative embedded software systems are widely adopted to engage the physical world. To make such software extremely reliable, very efficient and highly flexible, component-based embedded software development can be employed for the complex embedded systems, especially those based on object-oriented (OO) approaches. In this paper, we introduce a component-based embedded software framework and the features it inherits. We propose a quality assurance (QA) model for component-based embedded software development, which covers both the component QA and the system QA as well as their interactions. Furthermore, we propose a generic quality assessment environment for component-based embedded systems: ComPARE. ComPARE can be used to assess real-life off-the-shelf components and to evaluate and validate the models selected for their evaluation. The overall component-based embedded systems can then be composed and analyzed seamlessly.

Many mobile and wireless devices are connecting to the Internet nowadays, among them, mobile phones and PDAs are the most popular ones. Thus, in this paper, we will focus on how to develop embedded software running on the two devices by using design patterns and Java based software components. Notably, some components may be used directly in an embedded software system, whereas most components must be specialized prior to reuse. Developers have to identify the variation points on these components. In order to develop a reusable embedded software system, we will identify several variation points with some variants, and introduce some useful design patterns for implementing variation points. Consequently, we can customize an embedded software system just through attaching variants on corresponding variation point in our system.

The design patterns we are using are property container, strategy, decorator, and model-view-controller. The component technology we are using is J2ME. J2ME is a specification focused on the development of mobile applications. It provides a similar environment as standard Java environment. J2ME's components programming includes the Spotlet programming for PDA, and the MIDlet programming for Java phone. In addition, along with the XML, J2ME can also provide the XMIDlet programming for dynamic downloading and execution of XML-based applications for PDA and Java phones.

The definition of a transparent software architecture is one of the key issues in the early development phases for complex distributed and reactive software systems. In this paper, we show how to derive an architecture systematically for systems with communication models based on broadcasting. Adequate graphical description techniques for capturing interaction requirements and logical component architectures for broadcasting systems are unavailable so far. We introduce an extension to UML's sequence diagrams to capture broadcasting scenarios. Furthermore, we present methodological steps for constructively deriving structural and behavioral aspects of the architecture under consideration from the captured scenarios.

Automated generation of test cases is a prerequisite for fast testing. Whereas the research in automated test data generation addressed the creation of individual test points, test trajectory generation has attracted limited attention. In simple terms, a test trajectory is defined as a series of data points, with each (possibly multidimensional) point relying upon the value(s) of previous point(s). Many embedded systems use data trajectories as inputs, including closed-loop process controllers, robotic manipulators, nuclear monitoring systems, and flight control systems. For these systems, testers can either handcraft test trajectories, use input trajectories from older versions of the system or, perhaps, collect test data in a high fidelity system simulator. While these are valid approaches, they are expensive and time-consuming, especially if the assessment goals require many tests.

We developed a framework for expanding a small, conventionally developed set of test trajectories into a large set suitable, for example, for system safety assurance. Statistical regression is the core of this framework. The regression analysis builds a relationship between controllable independent variables and closely correlated dependent variables, which represent test trajectories. By perturbing the independent variables, new test trajectories are generated automatically. Our approach has been applied in the safety assessment of a fault tolerant flight control system. Linear regression, multiple linear regression, and autoregressive techniques are compared. The performance metrics include the speed of test generation and the percentage of "acceptable" trajectories, measured by the domain specific reasonableness checks.

Embedded systems have become ubiquitous and essential entities in our ever growing high-tech world. The backbone of today's information-highway infrastructure are embedded systems such as telecommunication systems. They demand high reliability, so as to prevent severe consequences of failures including costly repairs at remote sites. Technology changes mandate that embedded systems evolve, resulting in a demand for techniques for improving reliability of their future system releases. Reliability models based on software metrics can be effective tools for software engineering of embedded systems, because quality improvements are so resource-consuming that it is not feasible to apply them to all modules. Identification of the likely fault-prone modules before system testing, can be effective in reducing the likelihood of faults discovered during operations.

A software quality classification model is calibrated using software metrics from a past release, and is then applied to modules currently under development to estimate which modules are likely to be fault-prone. This paper presents and demonstrates an effective case-based reasoning approach for calibrating such classification models. It is attractive for software engineering of embedded systems, because it can be used to develop software reliability models using a faster, cheaper, and easier method. We illustrate our approach with two large-scale case studies obtained from embedded systems. They involve data collected from telecommunication systems including wireless systems. It is indicated that the level of classification accuracy observed in both case studies would be beneficial in achieving high software reliability of subsequent releases of the embedded systems.