Andreas Hjertström

A data-entity approach for component-based real-time embedded systems development

In this paper the data-entity approach for efficient design-time management of run-time data in component-based real-time embedded systems is presented. The approach formalizes the concept of a data entity which enable design-time modeling, management, documentation and analysis of run-time data items. Previous studies on data management for embedded real-time systems show that current data management techniques are not adequate, and therefore impose unnecessary costs and quality problems during system development. It is our conclusion that data management needs to be incorporated as an integral part of the development of the entire system architecture. Therefore, we propose an approach where run-time data is acknowledged as first class objects during development with proper documentation and where properties such as usage, validity and dependency can be modeled. In this way we can increase the knowledge and understanding of the system. The approach also allows analysis of data dependencies, type matching, and redundancy early in the development phase as well as in existing systems.

Design-time management of run-time data in industrial embedded real-time systems development

Efficient design-time management and documentation of run-time data elements are of paramount importance when developing and maintaining modern real-time systems. In this paper, we present the results of an industrial case-study in which we have studied the state of practice in data management and documentation. Representatives from five companies within various business segments have been interviewed and our results show that various aspects of current data management and documentation are problematic and not yet mature. Results show that companies today have a fairly good management of distributed signals, while internal ECU signals and states are, in many cases, not managed at all. This lack of internal data management results in costly development and maintenance and is often entirely dependent of the know-how of single individual experts. Furthermore, it has, in several cases, resulted in unused and excessive data in the systems due to the fact that whether or not a data is used is unknown.

Data management for component-based embedded real-time systems: The database proxy approach

We introduce the concept of database proxies intended to mitigate the gap between two disjoint productivity-enhancing techniques: component based software engineering (CBSE) and real-time database management systems (RTDBMS). The two techniques promote opposing design goals and their coexistence is neither obvious nor intuitive. CBSE promotes encapsulation and decoupling of component internals from the component environment, whilst an RTDBMS provide mechanisms for efficient and predictable global data sharing. A component with direct access to an RTDBMS is dependent on that specific RTDBMS and may not be useable in an alternative environment. For components to remain encapsulated and reusable, database proxies decouple components from an underlying database residing in the component framework, while providing temporally predictable access to data maintained in a database. Our approach provide access to features such as extensive data modeling tools, predictable access to hard real-time data, dynamic access to soft real-time data using standardized queries and controlled data sharing; thus allowing developers to employ the full potential of both CBSE and an RTDBMS. Our approach primarily targets embedded systems with a subset of functionality with real-time requirements. The implementation results show that the benefits of using proxies do not come at the expense of significant run-time overheads or less accurate timing predictions.

Introducing database-centric support in AUTOSAR

We propose to integrate a real-time database management system into the basic software of the AUTOSAR component model. This integration can be performed without violating the fundamental principles of the component-based approach of AUTOSAR. Our database-centric approach allows developers to focus on application development instead of reinventing data management techniques or develop solutions using internal data structures. We use state-of-the-art database pointer techniques to achieve predictable timing, and database proxies to maintain component encapsulation and independence of data-management strategies. The paper illustrates the feasibility of our proposal when database proxies are used to manage the data communication between components and to perform run-time monitoring on the virtual function bus. Our implementation results show that the above benefits do not come at the expense of less accurate timing predictions while only introducing a total application CPU overhead, in the order of 4%.

Database Proxies for Component-Based Real-Time Systems

We introduce the concept of database proxies capable of mitigating the gap between two disjoint productivity-enhancing techniques: Component Based Software Engineering (CBSE) and Real-Time Database Management Systems (RTDBMS). The coexistence of the two techniques is neither obvious nor intuitive since CBSE and RTDBMS promotes opposing design goals, CBSE promotes encapsulation and decoupling of component internals from the component environment, whilst RTDBMS provide mechanisms for efficient and predictable global data sharing. Database proxies decouple components from an underlying database residing in the component framework. This enables components to remain encapsulated and reusable, while providing temporally predictable access to data maintained in a database. We specifically target embedded systems with a subset of functionality with real-time requirements. Our implementation results show that the above benefits do not come at the expense of run-time overheads or less accurate timing predictions.

Database Proxy Tool Support in an AUTOSAR Development Environment

AUTOSAR has been introduced as a remedy for the increasing complexity and rising costs within automotive systems development. However, AUTOSAR does not provide sufficient support for the increased complexity with respect to data management. Database proxies have been presented as a promising solution to provide software component technologies with the capabilities of a state-of-the-art real-time database management system. In this paper, we show how an industrial AUTOSAR development environment can be extended to include support for real-time data management.