Visar Januzaj

Performance Modelling for Avionics Systems

The new paradigm of Integrated Modular Avionics (IMA) [1] necessitates the analysis and validation of non-functional requirements for IMA systems. This includes the analysis of their performability. In this paper we present an initial approach of a performance modelling framework, based on the SAE standardised modelling and analysis language AADL [2,3], to integrate performance analysis in the toolchain of this practical context. The proposed framework is a hybrid of static and dynamic systems analysis and includes aspects of performance evaluation.

Seamless testing for models and code

This paper describes an approach to model-based testing where a test suite is generated from a model and automatically concretized to drive an implementation. Motivated by an industrial project involving DO-178B compliant avionics software, where the models are UML activity diagrams and the implementation is ANSI C, we developed a seamless testing environment based on our test specification language FQL. We demonstrate how to apply FQL to activity diagrams in such a way that FQL test specifications easily translate from UML to C code. Our approach does not require any additional glue or auxiliary code but is fully automatic except for straightforward source code annotations that link source and model. In this way, we can check for modeled but unimplemented behavior and vice versa, and we can also evaluate the degree of abstraction between model and implementation.

An Application of Data Mining to Identify Data Quality Problems

Modern information systems consist of many distributed computer and database systems. The integration of such distributed data into a single data warehouse system is confronted with the well known problem of low data quality. In this paper we present an approach that facilitates a dynamic identification of spurious and error-prone data stored in a large data warehouse. The identification of data quality problems is based on data mining techniques, such as clustering, subspace clustering and classification. Furthermore, we present via a case study the applicability of our approach on real data. The experimental results show that our approach efficiently identifies data quality problems.

Timely time estimates

Estimations of execution time are essential for design and development of safety critical embedded real-time systems, such as avionics, automotive and aerospace systems. In such systems, execution time is part of the functional specification, hence correct behaviour requires sufficiently powerful target hardware to meet deadlines or achieve required polling rates, etc. Yet, grossly overestimated resource usage results in excessive cost per unit. For a proper choice of the target platform, qualitatively good execution time estimates are required at an early stage of the development process. In this paper we propose a framework which provides software engineers with execution time estimates of the software under development in a demand-driven manner, i. e., the engineers ask for timing information at program or function level with respect to different target hardware platforms. In a platform-independent manner we extract the necessary information from the code and combine it with platform-specific information, resulting in the time estimate. We implemented our framework on top of the test input generator FSHELL and its query language FQL. Preliminary experiments on C code show the viability of our approach.

A configuration approach for IMA systems

In this paper, we focus on system configurations of Integrated Modular Avionics (IMA) systems and present a novel approach for their calculation. We consider IMA systems based on ASAAC standards (STANAG 4626, EN 4660). These systems are modelled, by means of blueprints, using the SAE standardised modelling and analysis language AADL. For the calculation of system configurations, the required data is gathered from the system model and is transformed into a SAT modulo theory (SMT) formula. This formula includes a set of user input parameters, which steer the resource allocation. All feasible solutions satisfy the schedulability by a given set of scheduling schemes. The as schedulable considered configurations serve in choosing the final system configuration, for which a set of possible valid reconfigurations is calculated. To facilitate more compact allocations and increase the quality of (re-)configurations, we consider system modes. Both the chosen configuration and its corresponding reconfigurations are stored in the AADL system model, making all necessary data available within the same developing environment.

New challenges in the development of critical embedded systems: an aeromotive perspective

During the last decades, embedded systems have become increasingly important in highly safety-critical areas such as power plants, medical equipment, cars, and aeroplanes. The automotive and avionics domains are prominent examples of classical engineering disciplines where conflicts between costs, short product cycles and legal requirements concerning dependability, robustness, security, carbon footprint and spatial demands have become a pressing problem.

Towards Resource Consumption-Aware Programming

In order to check the fulfilment of non-functional requirements at an early system design and development stage, we provide a framework that facilitates the combination of platform-independent and platform-specific information in a query-based manner to calculate estimates for the resource consumption of the software under investigation at fine grained levels of code. Based on an already optimised intermediate representation of the source code, using a testing infrastructure for C code, we count the occurrence of instructions during program executions in a platform-independent manner. These instruction counters can be determined at program or function level. By combining these counters with cost information of a hardware platform we can provide resource consumption estimates. This allows the software developer to tailor the code steadily towards the non-functional characteristics of the software.

Data mining meets system modelling

Motivated by the system management concept of Integrated Modular Avionics (IMA), where the system is manually divided into a hierarchical structure of clusters of closely related system components, so called integration areas, we introduce a data mining-based approach to automatically calculate such integration areas or clusters. Thus, facilitating the modelling process by clustering software components with dense intercommunication, achieving in this way a reduced off-board intercommunication, once the software is mapped to the underlying hardware. Even though the idea emerged from the avionics domain, the proposed approach can be applied to other domains, e.g., automotive, as well.