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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.

In this paper the data-entity approach for efficientdesign-time management of run-time data in componentbasedreal-time embedded systems is presented. The approachformalizes the concept of a data entity which enabledesign-time modeling, management, documentationand analysis of run-time data items. Previous studies ondata management for embedded real-time systems showthat current data management techniques are not adequate,and therefore impose unnecessary costs and quality problemsduring system development. It is our conclusion thatdata management needs to be incorporated as an integralpart of the development of the entire system architecture.Therefore, we propose an approach where run-time datais acknowledged as first class objects during developmentwith proper documentation and where properties such asusage, validity and dependency can be modeled. In thisway we can increase the knowledge and understanding ofthe system. The approach also allows analysis of data dependencies,type matching, and redundancy early in the developmentphase as well as in existing systems.

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.

We propose to integrate a real-time databasemanagement system into the basic software of the AUTOSARcomponent model. This integration can be performed withoutviolating the fundamental principles of the component-basedapproach of the AUTOSAR standard. Our database-centricapproach allows developers to focus on application developmentinstead of reinventing data management techniques ordevelop solutions using internal data structures. We use stateof-the-art database pointer techniques to achieve predictabletiming, and database proxies to maintain component encapsulationand independence of data-management strategy. Thepaper illustrates the feasibility of our proposal when databaseproxies are used to manage the data communication betweencomponents and to perform run-time monitoring on the virtualfunction bus. Our implementation results show that the abovebenefits do not come at the expense of run-time overheadsor less accurate timing predictions. Under typical workloadconditions, our concept only introduces in the order of 4%CPU overhead.