J Johan Muskens

Predicting real-time properties of component assemblies: a scenario-simulation approach

This work addresses the problem of predicting timing properties of multitasking component assemblies during the design phase. For real-time applications, it is of vital importance to guarantee that the timing requirements of an assembly are met. We propose a simulation-based approach for predicting the real-time behaviour of an assembly based on models of its constituent components. Our approach extends the scenario-based method in [J. Muskens et al. (2004)] by offering a system model that is tailored to the domain of real-time applications. Contributions of This work include the possibility to handle the following features: mutual exclusion, combinations of aperiodic and periodic tasks and synchronization constraints. The analytical approach we used in previous work cannot handle these features. Therefore, we introduce the simulation-based approach. Our simulator provides data about dynamic resource consumption and real-time properties like response time, blocking time and number of missed deadlines per task. We have validated our approach using a video-decoder application.

Modelling of input-parameter dependency for performance predictions of component-based embedded systems

The guaranty of meeting the timing constraints during the design phase of real-time component-based embedded software has not been realized. To satisfy real-time requirements, we need to understand behaviour and resource usage of a system over time. In this paper, we address both aspects in detail by observing the influence of input data on the system behaviour and performance. We extend an existing scenario simulation approach that features the modelling of input parameter dependencies and simulating the execution of the models. The approach enables specification of the dependencies in the component models, as well as initialisation of the parameters in the application scenario model. This gives a component-based application designer an explorative possibility of going through all possible execution scenarios with different parameter initialisations, and finding the worst-case scenarios where the predicted performance does not satisfy the requirements. The identification of these scenarios is important because it avoids system redesign at the later stage. In addition, the conditional behaviour and resource usage modelling with respect to the input data provide more accurate prediction.

Generalizing Consistency Checking between Software Views

Inconsistencies between software views are a source of errors for software systems. In this paper we present a general approach that aids in finding inconsistencies between different views. This approach supports both intra phase consistency checking and inter phase consistency checking. The approach is suitable for detecting consistency problems between, for example, multiple diagrams in a UML design as well as between a design and an implementation. The approach is based on verification of rules using relation partition algebra. In this paper, we present two types of rules: obligations and the more commonly used constraints, which can be viewed as lower bounds and upper bounds, respectively. To check consistency between views, rules are derived from one view, the so-called prevailing view, and imposed on another view, the so-called subordinate view. Because our approach does not prescribe which views are prevailing, it can be used in any arbitrary process. Violations to rules can be expressed in terms of either the prevailing view or the subordinate view. Exceptions to rules are easiliy embedded in our general approach to consistency checking.

A component framework for consumer electronics middleware

Developers of Consumer Electronics (CE) devices face the problem of the ever increasing amount of software that needs to be developed. At the same time the time to market of their products needs to decrease. In other domains Component Based software development aids in solving the resulting problems. However, existing component frameworks fail to meet some of the requirements specific for the CE domain. In order to improve this situation a component-based framework has been developed. In this chapter we describe this framework and motivate the architectural choices. These choices are influenced by the requirements on the framework. Some of these requirements are specific for the CE domain, others are more general.

Prediction of Run-Time Resource Consumption in Multi-task Component-Based Software Systems

Embedded systems must be cost-effective. This imposesstrict requirements on the resource consumption of their applications. It is therefore desirable to be able to determine the resource consumption of applications as early as possible in its development. Only then, a designer is able to guarantee that an application will fit on a target device.

Integrity management in component based systems

There is a need for mechanisms for maintaining and restoring software integrity on deployed systems. Dynamic replacement, removal and addition of components in deployed systems is supported by most component models. This is needed to enable the software on a device to evolve in the period that it is owned by a consumer, but endangers the integrity of the software on these devices. For high volume consumer devices the challenge is to keep the devices operating reliable and robust in the period that it is owned, used and possibly reconfigured by a consumer. To this end, we propose mechanisms and tools, for maintaining system integrity on deployed systems.

Investigations in applying metrics to multi-view architecture models

The goal of our research is to develop industry-proof software architecture and design metrics. We identify a number of problems that arise in computing software architecture and design metrics in industrial settings that were not encountered in computing source-code metrics. These problems include the absence of a single, unifying representation for architectures and they arise from the fact that architecture diagrams are used in an informal manner. We describe our approach towards defining metrics for architectures and designs which are represented in the 4+1 views paradigm using UML. We report our experiences with architectural metrics in industrial settings.

A compositional claim-based component certification procedure

Component-based software construction is of much interest in software engineering due to its promise of black-box composition and independent deployment. Because of this black-box nature, users of components must be concerned with their trustworthiness, in particular when third parties are involved. Component certification is used to improve trust, usually relating the component to the party that made it. In order to support predictable assembly the certification procedure should also address extra-functional properties. In addition, certificates should remain valid across certain compositions. We present a certification procedure in the context of the ROBOCOP component architecture. We discuss specific requirements, introduce terminology and present a solution.

Introduction from session chair component models for dependable systems

This session introduces 8 papers in the area of component models for depenable systems. These papers are grouped into 3 themes.