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• 1.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Institutionen för datavetenskap Linköpings universitet. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Automatic Control. Department of Computer Science University of Virginia.
Toward Adaptive Control of QoS-Importance Decoupled Real-Time Systems2007In: IEEE International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks,2007, 2007Conference paper (Refereed)

This paper deals with differentiated services in real-time systems. Tasks submitted to a real-time system are differentiated with respect to importance and QoS requirements. We use feedback control to enforce the requirements in QoS and ensure a hierarchical admission policy based on the importance of the tasks. The results show that the requirements are met during steady state when the workload is constant. The feedback control approach does not satisfactorily manage QoS when there is a sudden and significant workload change (transient state) due to the time-variant nature of the system. To address this, we present preliminary and promising results using adaptive control, and report on some challenges we are facing when applying the theory.

• 2.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Software Engineering Institute, Carnegie Mellon University, USA. Dept. of Computer Science, University of Virginia, Charlottesville, USA. Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
Generalized performance management of multi-class real-time imprecise data services2005In: Real-Time Systems Symposium, 2005. RTSS 2005. 26th IEEE International, 2005, p. 12-49Conference paper (Other academic)

The intricacy of real-time data service management increases mainly due to the emergence of applications operating in open and unpredictable environments, increases in software complexity, and need for performance guarantees. In this paper we propose an approach for managing the quality of service of real-time databases that provide imprecise and differentiated services, and that operate in unpredictable environments. Transactions are classified into service classes according to their level of importance. Transactions within each service class are further classified into subclasses based on their quality of service requirements. In this way transactions are explicitly differentiated according to their importance and quality of service requests. The performance evaluation shows that during overloads the most important transactions are guaranteed to meet their deadlines and that reliable quality of service is provided even in the face of varying load and execution time estimation errors.

• 3.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology. Software Engineering Institute, Carnegie Mellon University, Pittsburgh, PA, USA. University of Virginia, USA.
Quantifying and Suppressing the Measurement Disturbance in Feedback Controlled Real-Time Systems2008In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 40, no 1, p. 44-76Article in journal (Refereed)

In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the dynamics of the system. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantify the disturbance present in the measured variable as a function of the data set size and the sampling period, and we propose a feedback control structure that suppresses the measurement disturbance. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability.

• 4.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology. University of Virginia, VA, USA.
Enhancing Feedback Control Scheduling Performance by On-line Quantification and Suppression of Measurement Disturbance2005In: Proceedings of the 11th IEEE Real-Time and Embedded Technology and Applications Symposium, 2005, p. 2-11Conference paper (Refereed)

In the control of continuous and physical systems, the controlled system is sampled sufficiently fast to capture the system dynamics. In general, this property cannot be applied to the control of computer systems as the measured variables are often computed over a data set, e.g., deadline miss ratio. In this paper we quantize the disturbance present in the measured variable as a function of the sampling period and we propose a measurement disturbance suppressive control structure. The experiments we have carried out show that a controller using the proposed control structure outperforms a traditional control structure with regard to performance reliability and adaptation.

• 5.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. University of Virginia.
Algorithms for Managing QoS for Real-Time Data Services Using Imprecise Computation2003In: Proceedings of the 9th International Conference on Real-Time and Embedded Computing Systems and Application (RTCSA 2003), Springer Verlag , 2003Conference paper (Refereed)
• 6.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. University of Virginia.
Algorithms for managing QoS for real-time data services using imprecise computation2004In: Real-Time and Embedded Computing Systems and Applications 9th International Conference, RTCSA 2003, Tainan City, Taiwan, February 18-20, 2003. Revised Papers / [ed] Jing Chen and Seongsoo Hong, Springer Berlin/Heidelberg, 2004, Vol. 2968, p. 136-157Chapter in book (Refereed)

Lately the demand for real-time data services has increased in applications where it is desirable to process user requests within their deadlines using fresh data. The real-time data services are usually provided by a real-time database (RTDB). Here, since the workload of the RTDBs cannot be precisely predicted, RTDBs can become overloaded. As a result, deadline misses and freshness violations may occur. To address this problem we propose a QoS-sensitive approach to guarantee a set of requirements on the behavior of RTDBs. Our approach is based on imprecise computation, applied on both data and transactions. We propose two algorithms to dynamically balance the workload and the quality of the data and transactions. Performance evaluations show that our algorithms give a robust and controlled behavior of RTDBs, in terms of transaction and data quality, even for transient overloads and with inaccurate run-time estimates of the transactions.

• 7.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Dept. of Computer Science University of Virginia.
Error-Driven QoS Management in Imprecise Real-Time Databases2003In: Euromicro Conference on Real-Time Systems,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, p. 63-Conference paper (Refereed)

In applications such as web-applications, e-commerce, and engine control, the demand for real-time data services has increased. In these applications, requests have to be processed within their deadlines using fresh data. Since the workload of these systems cannot be precisely predicted, they can become overloaded and as a result, deadline and freshness violations may occur. To address this problem we propose a QoS-sensitive approach based on imprecise computation, applied on transactions and data objects. We propose two algorithms FCS-HEF and FCS-HEDF that give a robust and controlled behavior of RTDBs in terms of transaction and data preciseness, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms including FCS-EDF, which schedules the transactions using EDF.

• 8.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Dept. of Computer Science University of Virginia.
Specification and Management of QoS in Imprecise Real-Time Databases2003In: International Database Engineering and Applications Symposium,2003, Los Alamitos, CA, USA: IEEE Computer Society , 2003, p. 192-Conference paper (Refereed)

Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services. Since the workload of real-time databases RTDBs, providing real-time data services, cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in a damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework consisting of a model for expressing QoS requirements in terms of data and transaction preciseness, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of RTDBs, even for transient overloads and with inaccurate run-time estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms, including FCS-EDF that schedules the transactions using EDF and feedback control.

• 9.
Linköping University, Department of Computer and Information Science, RTSLAB. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB. Linköping University, The Institute of Technology. Dept. of Computer Science, University of Virginia, Charlottesville, USA.
Specification and Management of QoS in Real-Time Databases Supporting Imprecise Computations2006In: IEEE Transactions on Computers, ISSN 0018-9340, Vol. 55, no 3, p. 304 - 319Article in journal (Refereed)

Real-time applications such as e-commerce, flight control, chemical and nuclear control, and telecommunication are becoming increasingly sophisticated in their data needs, resulting in greater demands for real-time data services that are provided by real-time databases. Since the workload of real-time databases cannot be precisely predicted, they can become overloaded and thereby cause temporal violations, resulting in damage or even a catastrophe. Imprecise computation techniques address this problem and allow graceful degradation during overloads. In this paper, we present a framework for QoS specification and management consisting of a model for expressing QoS requirements, an architecture based on feedback control scheduling, and a set of algorithms implementing different policies and behaviors. Our approach gives a robust and controlled behavior of real-time databases, even for transient overloads and with inaccurate runtime estimates of the transactions. Further, performance experiments show that the proposed algorithms outperform a set of baseline algorithms that uses feedback control.

• 10.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. University of Virginia, USA. Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
Experimental Evaluation of Linear Time-Invariant Models for Feedback Performance Control in Real-Time Systems2007In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, no 3, p. 209-238Article in journal (Refereed)

In recent years a new class of soft real-time applications operating in unpredictable environments has emerged. Typical for these applications is that neither the resource requirements nor the arrival rates of service requests are known or available a priori. It has been shown that feedback control is very effective to support the specified performance of dynamic systems that are both resource insufficient and exhibit unpredictable workloads. To efficiently use feedback control scheduling it is necessary to have a model that adequately describes the behavior of the system. In this paper we experimentally evaluate the accuracy of four linear time-invariant models used in the design of feedback controllers. We introduce a model (DYN) that captures additional system dynamics, which a previously published model (STA) fails to include. The accuracy of the models are evaluated by validating the models with regard to measured data from the controlled system and through a set of experiments where we evaluate the performance of a set of feedback control schedulers tuned using these models. From our evaluations we conclude that second order models (e.g., DYN) are more accurate than first order models (e.g. STA). Further we show that controllers tuned using second order models perform better than controllers tuned using first order models.

• 11.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Department of Computer Science University of Virgina. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
QoD Adaptation for Achieving Lifetime Predictability of WSN Nodes Communicating over Satellite Links2007In: International Conference on Networked Sensing Systems INSS,2007, IEEE , 2007, p. 19-26Conference paper (Refereed)

In this paper we propose an architecture consisting of a particular type of node, namely a communication server that collects and aggregates data, and establishes a link between the users and the sensor nodes through satellite communication. A key challenge with satisfying a lifetime requirement of the communication server is the unpredictability of the sensor data volume arriving at the communication server and the transmission power of the satellite terminal. To provide lifetime predictability we propose an approach that automatically adjusts the quality of the data such that the specified lifetime if achieved. We have shown through an extensive evaluation that the approach manages to provide an actual lifetime within 2% of the specified lifetime despite variations in workload and communication link quality.

• 12.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Enea Epact. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Department of Computer Science University of Virginia, USA.
Finite Horizon QoS Prediction of Reconfigurable Firm Real-Time Systems2006In: IEEE International Conference on Embedded and Real-Time Computing Systems and Applications,2006, Los Alamitos, California, USA: IEEE Computer Society , 2006, p. 233-Conference paper (Refereed)

Updating real-time system software is often needed in response to errors and added requirements to the software. Stopping a running application, updating the software, and then restarting the application is not suitable for systems with high availability requirements. On the other hand, dynamically updating a system may increase the execution time of the tasks, thus, degrading the performance of the system. Degradation is not acceptable for performance-critical real-time systems as there are strict requirements on the performance. In this paper we present an approach that enables dynamic reconfiguration of a real-time system, where the performance of the system during a reconfiguration satisfies a given worst-case performance specification. Evaluation shows that the presented method is efficient in guaranteeing the worst-case performance of dynamically reconfigurable firm real-time systems.

• 13.
Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. University of Virginia, Charlottesville, USA.
Robust Quality Management for Differentiated Imprecise Data Services2004In: Proceedings of the 25th IEEE International Real-Time Systems Symposium, 2004, p. 265-275Conference paper (Refereed)

Several applications, such as Web services and e-commerce, are operating in open environments where the workload characteristics, such as the load applied on the system and the worst-case execution times, are inaccurate or even not known in advance. This implies that transactions submitted to a real-time database cannot be subject to exact schedulability analysis given the lack of a priori knowledge of the workload. In this paper we propose an approach, based on feedback control, for managing the quality of service of real-time databases that provide imprecise and differentiated services, given inaccurate workload characteristics. For each service class, the database operator specifies the quality of service requirements by explicitly declaring the precision requirements of the data and the results of the transactions. The performance evaluation shows that our approach provides reliable quality of service even in the face of varying load and inaccurate execution time estimates.

• 14. Gustafsson, Fredrik
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. University of Virginia.
Process Migration in Distributed Real-Time Systems2002In: Proceedings of the 8th International Conference on Real-Time Computing Systems and Applications (RTCSA'02), 2002Conference paper (Refereed)
• 15.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Data Freshness and Overload Handling in Embedded Systems2006In: 12th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2006, Los Alamitos, CA, USA: IEEE Computer Society, 2006, p. 173-182Conference paper (Refereed)

In this paper we consider data freshness and overload handling in embedded systems. The requirements on data management and overload handling are derived from an engine control software. Data items need to be up-to-date, and to achieve this data dependencies must be considered, i.e., updating a data item requires other data items are up-to-date. We also note that a correct result of a calculation can in some cases be calculated using a subset of the inputs. Hence, data dependencies can be divided into required and not required data items, e.g., only a subset of data items affecting the fuel calculation in an engine control needs to be calculated during a transient overload in order to reduce the number of calculations. Required data items must always be up-to-date, whereas not required data items can be stale. We describe an algorithm that dynamically determines which data items need to be updated taking workload, data freshness, and data relationships into consideration. Performance results show that the algorithm suppresses transient overloads better than $(m,k)$- and skip-over scheduling combined with established algorithms to update data items. The performance results are collected from an implementation of a real-time database on the real-time operating system $\mu$C/OS-II. To investigate whether the system is occasionally overloaded an offline analysis algorithm estimating period times of updates is presented.

• 16.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Data Management in Real-Time Systems: a Case of On-Demand Updates in Vehicle Control Systems2004In: The 10th IEEE Real-Time and Embedded Technology and Applications Symposium,2004, Los Alamitos, CA, USA: IEEE Computer Society Press , 2004, p. 182-Conference paper (Refereed)

Real-time and embedded applications normally have constraints both with respect to timeliness and freshness of data they use. At the same time it is important that the resources are utilized as efficient as possible, e.g., for CPU resources unnecessary calculations should be lowered as much as possible. This is especially true for vehicle control systems, which are our targeting application area. The contribution of this paper is a new algorithm ODTB for updating data items that can skip unnecessary updates allowing for better utilization of the CPU. Performance evaluations on an engine electronic control unit for automobiles show that a database system using the new updating algorithm reduces the number of recalculations to zero in steady states. We also evaluate the algorithm using a simulator and show that the ODTB performs better than well-established updating algorithms up to 50 procent more committed transactions.

• 17.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Dynamic On-Demand Updating of Data in Real-Time Database Systems2004In: in 19th Annual ACM Symposium on Applied Computing Special track on Embedded Systems (SAC04), 2004Conference paper (Other academic)
• 18.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Dynamic on-demand updating of data in real-time database systems2004In: The 2004 ACM symposium on Applied computing,2004, New York: ACM Press , 2004, p. 846-Conference paper (Refereed)

The amount of data handled by real-time and embedded applications is increasing. Also, applications normally have constraints with respect to freshness and timeliness of the data they use, i.e., results must be produced within a deadline using accurate data. This calls for data-centric approaches when designing embedded systems, where data and its meta-information temporal correctness requirements etc are stored centrally. The focus of this paper is on maintaining data freshness in soft real-time embedded systems and the target application is vehicular systems. The contributions of this paper are three-fold. We i define a specific notion of data freshness by adopting data similarity in the value-domain of data items using data validity bounds that express required accuracy of data, ii present a scheme for managing updates in response to changes in the data items; and iii present a new on-demand scheduling algorithm, On-Demand Depth-First Traversal denoted ODDFT, for enforcing data freshness by scheduling and executing update transactions. Performance experiments show that, by using our updating scheme and introduced notion of data freshness in the value-domain, computational work imposed by updates is reduced for both the new ODDFT and well-established on-demand algorithms. Moreover, ODDFT improves the consistency of produced results compared to well-established algorithms.

• 19.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Performance Evaluations and Estimations of Workload of On-Demand Updates in Soft Real-Time Systems2007In: 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2007, IEEE Computer Society, 2007, p. 337-344Conference paper (Refereed)

Data being used in real-time systems must be up-to-date to produce correct results. The use of outdated data can have catastrophic consequences since calculated control signals are based on stale data. Two distinct methods to update data exist: (i) dedicated tasks (DT) update data items, and (ii) on-demand (OD) updating being a conditioned part of the execution flow of tasks. On-demand updating has not been studied in terms of CPU utilization analysis for real-time systems. This paper studies on-demand updating in terms of (i) imposed workload and compares the workload to deferrable scheduling (DS), and (ii) analytical formula for estimating workload to be used in CPU utilization based schedulability tests. It is found that on-demand updating uses less workload for updates compared to DS, which suggests on-demand updating should be used for resource constrained systems. However, using on-demand updating makes the execution times of updates unpredictable, which currently gives two possibilities (i) be pessimistic and assume all updates always execute or (ii) be less pessimistic but estimate the times between executions of updates. This paper devises a formula for such estimates and compares their result to approach (i). Evaluations show the formula can be useful for soft real-time systems.

• 20.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mecel AB. GM Powertrain Europe AB. GM Powertrain Europe AB.
Database Functionality in Engine Management System2006In: SAE World Congress,2006, Proceedings of Software/Hardware Systems SAE World Congress 2006: SAE , 2006Conference paper (Refereed)

Embedded systems of today need to manage more data than ever before. The main reasons for the increase in number of data items are increased functional requirements on the software. With a larger amount of data to manage comes the problems of storing data and its meta-information, sharing between programmers which data items exist, and ensuring freshness and consistency requirements of the data items. In this work we focus on efficient data management in embedded systems, and develop a database for such systems. The database has support for transactions, snapshots, and data freshness. We argue that the software maintenance efforts can be reduced using a database, and our performance results show that the performance can be increased without affecting consistency of data values.

• 21.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
A similarity-aware multiversion concurrency control and updating algorithm for up-to-date snapshots of data2005In: The 17th Euromicro Conference on Real-Time Systems ECRTS05,2005, Washington, DC, USA: IEEE Computer Society Press , 2005, p. 229-Conference paper (Refereed)

Real-time databases handle reading and writing of data with time constraints on transactions. Normally, data items in a real-time system have freshness requirements which need to be guaranteed, and for many transactions it is important that accessed data items origin from the same system state, which can be ensured by letting the transactions read a snapshot of the database. In this context, a snapshot at a specific time represents values on data items that were stored in the database at this time. Furthermore, similar values can be considered equal because values within given bounds do not affect the results from calculations. Previous work shows that using similarity among values of data items greatly increases the performance because there is a possibility to skip calculations. In this paper we present the MVTO-S concurrency control algorithm, which supports similarity and multiple versions of data and ensures that transactions read an up-to-date snapshot of a database. Performance evaluations show that MVTO-S increases the performance considerably compared to well-established single-version concurrency control algorithms.

• 22.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Engineering Active Behavior of Embedded Software to Improve Evolution and Performance: an Aspect-Oriented Approach2007In: The 22nd Annual ACM Symposium on Applied Computing,2007, New York: ACM , 2007Conference paper (Refereed)

In this paper we propose a novel aspect-oriented scheme for implementing active behavior in embedded software with requirements on data freshness. The scheme improves system performance by combining active behavior in terms of event-condition-action (ECA) rules and on-demand updating. We design and implement the scheme in terms of aspects, thereby exploiting aspect-oriented programming technology to efficiently handle crosscutting nature of active behavior. The benefits of our approach are demonstrated using a case study of an embedded database system called COMET. Namely, simulations on the COMET database indicate that its performance increases by incorporating our scheme. Furthermore, using the COMET example we show that aspect-oriented implementation of active behavior has benefits when it comes to easier evolution of the system.

• 23.
Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
Value-driven multi-class overload management in real-time database systems1999Doctoral thesis, monograph (Other academic)

In complex real-time applications, real-time systems handle significant amounts of information that must be managed efficiently, motivating the need for incorporating real-time database management into real-time systems. However, resource management in real-time database systems is a complex issue. Since these systems often operate in environments of imminent and transient overloads, efficient overload handling is crucial to the performance of a real-time database system.

In this thesis, we focus on dynamic overload management in real-time database systems. The multi-class workload consists of transaction classes having critical transactions with contingency transactions and non-critical transactions. Non-critical transaction classes may have additional requirements specifying the minimum acceptable completion ratios that should be met in order to maintain system correctness. We propose a framework which has been implemented and evaluated for resolving transient overloads in such workloads.

The contributions of our work are fourfold as the framework consists of (i) a new scheduling architecture and (ii) a strategy for resolving transient overloads by re-allocating resources, (iii) a value-driven overload management algorithm (OR-ULD) that supports the strategy, running in O(n log n) time (where n is the number of transactions), and (iv) a bias control mechanism (OR-ULD/BC). The performance of OR-ULD and OR-ULD/BC is evaluated by extensive simulations. Results show that, within a specified operational envelope, OR-ULD enforces critical time constraints for multi-class transaction workloads and OR-ULD/BC further enforces minimum class completion ratio requirements.

• 24.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Högskolan i Skövde. University of Virginia.
Using Artificial Neural Networks for Admission Control in Firm Real-Time Systems2002In: Proceedings of the 8th InternationaConference on Real-Time Computing Systems and Applications (RTCSA'02), Tokyo, Japan, March 2002., 2002Conference paper (Refereed)
• 25.
Mälardalen University .
Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Pessimistic Concurrency-Control and Versioning to Support Database Pointers in Real-Time Databases2004In: 16th Euromicro Conference on Real-Time Systems ECRTS04,2004, Los Alamitos, California: IEEE Computer Society Press , 2004Conference paper (Refereed)

In this paper we present a concurrency control algorithm that allows co-existence of soft real-time, relational database transactions, and hard real-time database pointer transactions in real-time database management systems. The algorithm uses traditional pessimistic concurrency control i.e. locking for soft transactions and versioning for hard transactions to allow them to execute regardless of any database lock. We provide formal proof that the algorithm is deadlock free and formally verify that transactions have atomic semantics. We also present an evaluation that demonstrates significant benefits for both soft and hard transactions when our algorithm is used. The proposed algorithm is suited for resource-constrained safety critical, real-time systems that have a mix of hard real-time control applications and soft real-time management, maintenance, or user-interface applications.

• 26.
Mälardalen University .
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University . Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
COMET: A Component-Based Real-Time Database for Automotive Systems2004In: Workshop on Software Engineering for Automotive Systems at 26th International Conference on Software engineering ICSE04,2004, 2004Conference paper (Refereed)

With the increase of complexity in automotive control systems, the amount of data that needs to be managed is also increasing. Using a real-time database management system (RTDBMS) as a tightly integrated part of the software development process can give significant benefits with respect to data management. However, the variability of data management requirements in different systems, and the heterogeneousness of the nodes within a system may require a distinct database configuration for each node. In this paper we introduce a software engineering approach for generating RTDBMS configurations suitable for resource-constrained automotive control systems, denoted the COMET development suit. Using software engineering tools to assist developers with design and analysis of the system under development, different database configurations can be generated from pre-fabricated components. Each generated COMET database contains only functionality required by the node it is executing on.

• 27.
Mälardalen University .
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Database Pointers: a Predictable Way of Manipulating Hot Data in Hard Real-Time Systems2003In: 9th International Conference on Real-Time and Embedded Computing Systems and Applications RTCSA 2003,2003, Heidelberg: Springer Verlag , 2003, p. 454-Conference paper (Refereed)

Traditionally, control systems use ad hoc techniques such as shared internal data structures, to store control data. However, due to the increasing data volume in control systems, these internal data structures become increasingly dicult to maintain. A real-time database management system can provide an efficient and uniform way to structure and access data. However the drawback with database management systems is the overhead added when accessing data. In this paper we introduce a new concept called database pointers, which provides fast and deterministic accesses to data in hard real-time database management systems compared to traditional database management systems.The concept is especially benefcial for hard real-time control systems where many control tasks each use few data elements at high frequencies. Database pointers can co-reside with a relational data model, and any updates made from the database pointer interface are immediately visible from the relational view. We show the effciency with our approach by comparing it to tuple identifers and relational processing.

• 28.
Mälardalen University, Sweden.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Mälardalen University, Sweden. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Database pointers: A predictable way of manipulating hot data in hard real-time systems2005In: Real-Time and Embedded Computing Systems and Applications: 9th International Conference, RTCSA 2003, Tainan City, Taiwan, February 18-20, 2003. Revised Papers / [ed] Jing Chen and Seongsoo Hong, Springer Berlin/Heidelberg, 2005, Vol. 2968, p. 454-465Chapter in book (Refereed)

Traditionally, control systems use ad hoc techniques such as shared internal data structures, to store control data. However, due to the increasing data volume in control systems, these internal data structures become increasingly difficult to maintain. A real-time database management system can provide an efficient and uniform way to structure and access data. However the drawback with database management systems is the overhead added when accessing data. In this paper we introduce a new concept called database pointers, which provides fast and deterministic accesses to data in hard real-time database management systems compared to traditional database management systems. The concept is especially beneficial for hard real-time control systems where many control tasks each use few data elements at high frequencies. Database pointers can co-reside with a relational data model, and any updates made from the database pointer interface are immediately visible from the relational view. We show the efficiency with our approach by comparing it to tuple identifiers and relational processing.

• 29.
Mälardalen University, Västerås.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Mälardalen University, Västerås. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Volvo Construction, Eskilstuna.
Data Management Issues in Vehicle Control Systems: A Cae Study2002In: Proceedings of the 14th Euromicro Conference on Real Time Systems, 2002, p. 249-256Conference paper (Refereed)

In this paper we present a case study of a class of embedded hard real-time control applications in the vehicular industry that, in addition to meeting transaction and task deadlines, emphasize data validity requirements. We elaborate on how a database could be integrated into the studied application and how the database management system(DBMS) could be designed to suit this particular class of systems.

• 30.
Chalmers University of Gothenburg, Sweden.
Chalmers University of Gothenburg, Sweden; Ericsson, Sweden; University of Gothenburg, Sweden; Volvo Cars, Sweden; Volvo AB, Sweden. Chalmers University of Gothenburg, Sweden; Chalmers University of Gothenburg, Sweden. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Chalmers University of Gothenburg, Sweden; University of Skovde, Sweden. Volvo Car Corp, Sweden. Volvo Car Corp, Sweden. Ericsson, Sweden. SAAB AB, Sweden.
Selecting software reliability growth models and improving their predictive accuracy using historical projects data2014In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 98, p. 59-78Article in journal (Refereed)

During software development two important decisions organizations have to make are: how to allocate testing resources optimally and when the software is ready for release. SRGMs (software reliability growth models) provide empirical basis for evaluating and predicting reliability of software systems. When using SRGMs for the purpose of optimizing testing resource allocation, the models ability to accurately predict the expected defect inflow profile is useful. For assessing release readiness, the asymptote accuracy is the most important attribute. Although more than hundred models for software reliability have been proposed and evaluated over time, there exists no clear guide on which models should be used for a given software development process or for a given industrial domain. Using defect inflow profiles from large software projects from Ericsson, Volvo Car Corporation and Saab, we evaluate commonly used SRGMs for their ability to provide empirical basis for making these decisions. We also demonstrate that using defect intensity growth rate from earlier projects increases the accuracy of the predictions. Our results show that Logistic and Gompertz models are the most accurate models; we further observe that classifying a given project based on its expected shape of defect inflow help to select the most appropriate model.

• 31.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Empowering Configurable QoS Management in Real-Time Systems2005In: Proceedings of the Fourth ACM SIG International Conference on Aspect-Oriented Software Development AOSD05,2005, USA: ACM Press , 2005Conference paper (Refereed)

Current Quality of Service (QoS) management methods in real-time systems using feedback control loop lack support for configurability and reusability as they cannot be configured for a target application or reused across different applications. In this paper we present a method for developing reconfigurable feedback-based QoS management for real-time systems, denoted Re-QoS. By combining component-based design with aspect-oriented software development Re-QoS enables successful handling of crosscutting nature of QoS policies, as well as evolutionary design of real-time systems and QoS management architectures. Re-QoS defines a QoS aspect package, which is an implementation of a set of aspects and components that provide a number of different QoS policies. By adding a QoS aspect package to an existing system without QoS guarantees, we are able to use the same system in unpredictable environments where performance guarantees are essential. Furthermore, by exchanging aspects within the QoS aspect package one can efficiently tailor the QoS management of a real-time system based on the application requirements. We demonstrate the usefulness of the concept on a case study of an embedded real-time database system, called COMET. Using the COMET example we show how a real-time database system can be adapted to be used in different applications with distinct QoS needs.

• 32.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Providing configurable QoS management in real-time systems with QoS aspect packages2006In: Transactions on Aspect-Oriented Software Development II / [ed] Awais Rashid and Mehmet Aksit, Springer Berlin/Heidelberg, 2006, Vol. 4242, p. 256-288Chapter in book (Refereed)

Current quality of service (QoS) management approaches in real-time systems lack support for configurability and reusability as they cannot be configured for a target application or reused across many applications. In this paper we present the concept of a QoS aspect package that enables developing configurable QoS management for real-time systems. A QoS aspect package represents both the specification and the implementation of a set of aspects and components that provide a number of QoS policies. A QoS aspect package enables upgrades of already existing systems to support QoS performance assurance by adding aspects and components from the package. Furthermore, a family of real-time systems can easily be developed by adding aspects from the QoS aspect package into an existing system configuration. We illustrate the way a family of real-time database systems is developed using the QoS aspect package with a case study of an embedded real-time database system, called COMET. Our experiments with the COMET database have shown that it is indeed possible to design a real-time system without QoS management and then with a reasonable effort add the QoS dimension to the system using a QoS aspect package.

• 33.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Institutionen för datavetenskap Linköpings universitet. Institutionen för datavetenskap Linköpings universitet. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Dynamically Reconfigurable QoS-aware Embedded Systems2007In: Embedded Systems: Status and Perspective / [ed] Raj Kamal, USA: American Scientific Publisher , 2007, 2, p. -633Chapter in book (Other academic)

This book, equally applicable for a CSE or ECE course, gives an extensive account of Embedded Systems, keeping a balanced coverage of hardware and software concepts. Adhering to syllabus needs, this title is ‘microprocessor’ and ‘software design methodology’ specific, giving due weightage to architecture, programming and design aspects.

• 34.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Ensuring Real-Time Performance Guarantees in Dynamically Reconfigurable Embedded Systems2005In: IFIP International Conference on Embedded And Ubiquitous Computing EUC,2005, Heidelberg: Springer Verlag , 2005, p. 131-Conference paper (Refereed)

In this paper we present a quality of service (QoS) adaptive framework for dynamic reconfiguration of component-based real-time systems. Our framework is light-weighted enabling reconfiguration in resource constrained embedded environments. Furthermore, it is possible to reconfigure both components and aspects of a system, hence, enabling finer tuning of a real-time system. Real-time QoS guarantees are maintained in the system and under reconfiguration by employing feedback-based scheduling methods.

• 35.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Ensuring real-time performance guarantees in dynamically reconfigurable embedded systems2005In: Embedded and Ubiquitous Computing – EUC 2005: International Conference EUC 2005, Nagasaki, Japan, December 6-9, 2005. Proceedings / [ed] Laurence T. Yang, Makoto Amamiya, Zhen Liu, Minyi Guo and Franz J. Rammig, Springer Berlin/Heidelberg, 2005, Vol. 3824, p. 131-141Chapter in book (Refereed)

In this paper we present a quality of service (QoS) adaptive framework for dynamic reconfiguration of component-based realtime systems. Our framework is light-weighted enabling reconfiguration in resource constrained embedded environments. Furthermore, it is possible to reconfigure both components and aspects of a system, hence, enabling finer timing of a real-time system. Real-time QoS guarantees are maintained in the system and under reconfiguration by employing feedback-based scheduling methods.

• 36.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Separating Active and On-demand Behavior of Embedded Systems into Aspects2006In: Workshop on Non-functional Properties of Embedded Systems NFPES06,2006, Berlin: VDE VERLAG GMBH , 2006Conference paper (Refereed)
• 37.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Structuring Criteria for the Design of Component-Based Real-Time Systems2004In: IADIS International Conference on Applied Computing 2004,2004, Lisbon: IADIS Press , 2004, p. 401-Conference paper (Refereed)

Using component-based software development in real-time system development offers significant benefits especially in enabling configurability, and rapid development and deployment of real-time software. Successful integration of component-based software development into real-time system development is greatly dependent on identifying issues that a design method for component-based real-time systems needs to address. The issues focused on by existing design approaches are decomposition of a real-time system into tasks and temporal analysis, while issues such as components, their relationship to tasks, and separation of concerns are not addressed. In this paper, we identify the criteria a design method for component-based real-time systems should fulfill to enable efficient, reuse-oriented, development of reliable and configurable real-time systems. The criteria include a real-time component model that supports mapping of components to tasks, separation of concerns in real-time systems through the notion of different types of aspects, and composition support, namely support for configuration and analysis of the composed real-time software. By introducing a new set of criteria for the design of component-based real-time systems, we help bridging the gap between the real-timeand software engineering community and offer a good basis for evaluating existing, and developing new, design methods for building component-based real-time systems.

• 38.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University . Mälardalen University .
Aspect-Level Worst-Case Execution Time Analysis of Real-Time Systems Compositioned Using Aspects and Components2003In: 27th IFAC IFIP IEEE Workshop on Real-Time Programming WRTP03,2003, Kidlington: Elsevier , 2003, p. 129-Conference paper (Refereed)

Increasing complexity in development of real-time systems accompanied by the demand for enabling their configurability requires the integration of aspect-oriented software development with real-time system development. Since software technology for building real-time systems has to support predictability in the time domain, methods and tools for analyzing temporal behavior of the aspect-oriented software are needed. Knowing worst-case execution time is of primary importance for timing analysis of real-time systems. We contribute by providing support for predictable aspect-oriented software development, by enabling symbolic worst-case execution time analysis of the aspect-oriented software systems.

• 39.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University . Mälardalen University .
Aspect-Level WCET Analyzer: a Tool for Automated WCET Analysis of a Real-Time Software Composed Using Aspects and Components2003In: 3rd International Workshop on Worst-Case Execution Time Analysis WCET 2003,2003, 2003Conference paper (Refereed)

Increasing complexity in development of real-time systems requires the integration of new software engineering techniques, such as aspect-oriented and component-based software development,with real-time system development. Since software technology for building real-time systems has to support timeliness,methods and tools for analyzing temporal behavior of the softwarecomposed out of components and aspects are needed. We contribute by providing a tool that enables automated worst-case execution time analysis of different configurations of aspects and components.

• 40.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Development Environment for Configuration and Analysis of Embedded Real-Time Systems2005In: Proceedings of the 4th AOSD International Workshop on Aspects, Components, and Patterns for Infrastructure Software ACP4IS05,2005, 2005Conference paper (Refereed)

In this paper we present a tool framework that provides developers of real-time systems with support for building and configuring a system out of components and aspects, as well as real-time analysis of the configured system. This way a real-time system can efficiently be configured to meet functional requirements and analyzed to ensure that non-functional requirements are also fulfilled, e.g., available resources such as memory and CPU. We illustrate the usability of the tool by a case study of an embedded real-time database system.

• 41.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Modular Verification of Reconfigurable Components2005In: Component-Based Software Development for Embedded Systems: An Overview on Current Research Trends / [ed] Colin Atkinson (Editor), Christian Bunse, Hans-Gerhard Gross, Christian Peper, Heidelberg: Springer Verlag , 2005, 1, p. -353Chapter in book (Other academic)

This book provides a good opportunity for software engineering practitioners and researchers to get in sync with the current state-of-the-art and future trends in component-based embedded software research. The book is based on a selective compilation of papers that cover the complete component-based embedded software spectrum, ranging from methodology to tools. Methodology aspects covered by the book include functional and non-functional specification, validation, verification, and component architecture. As tools are a critical success factor in the transfer from academia-generated knowledge to industry-ready technology, an important part of the book is devoted to tools. This state-of-the-art survey contains 16 carefully selected papers organised in topical sections on specification and verification, component compatibility, component architectures, implementation and tool support, as well as non-functional properties.

• 42.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Modular verification of reconfigurable components2005In: Component-Based Software Development for Embedded Systems: An Overview of Current Research Trends / [ed] Colin Atkinson, Christian Bunse, Hans-Gerhard Gross and Christian Peper, Springer Berlin/Heidelberg, 2005, Vol. 3778, p. 59-81Chapter in book (Refereed)

This chapter presents a framework for modular verification of reconfigurable real-time components. The framework enables proving that the reconfiguration of components via aspect weaving provides expected functional and temporal behavior in the reconfigured component. Within the framework we formally represent components and aspects as augmentations of timed automata. The verification is based on two algorithms: an algorithm that extracts necessary information into component verification interfaces, and an algorithm that checks, on an aspect, whether the property is preserved upon reconfiguration. Hence, the method ensures that components are verified only once for a particular property, while the property satisfaction under reconfiguration is checked only on aspects. Verification interfaces for a given property can be reused for multiple aspects and reconfigurations.

• 43.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University .
Aspects and Components in Real-Time System Development: Towards Reconfigurable and Reusable Software2004In: Journal of Embedded Computing, ISSN 1740-4460, E-ISSN 1875-9025, Vol. 1, no 1Article in journal (Refereed)

Increasing complexity of real-time systems, and demands for enabling their configurability and reusability are strong motivations for applying new software engineering principles, such as aspect-oriented and component-based development.In this paper we introduce a novel concept of aspectual component-based real-time system development. The concept is based on a design method that assumes composition of real-time systems into components and aspects, and provides a real-time component model that supports the notion of time and temporal constraints, space and resource management constraints, and composability. Initial results show that the successful application of the proposed concept has a positive impact on real-time system development in enabling efficient configuration of real-time systems, improved reusability and flexibility of real-time software, and modularization of crosscutting concerns. We provide arguments for this by presenting an application of the proposed concept on the design and development of a configurable embedded real-time atabase, called COMET. Furthermore, using the COMET system as an example, we introduce a novel way of handling concurrency in a real-time database system, where concurrency is modeled as an aspect crosscutting the system.

• 44.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Mälardalen University, Västerås. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Mälardalen University, Västerås.
Integrating Symbolic Worst-Case Execution Time Analysis with Aspect-Oriented System Development2002In: OOPSLA 2002 Workshop on Tools for Aspect-Oriented Software Development (Seattle, WA), 2002Conference paper (Other academic)
• 45.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Mälardalen University . Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Mälardalen University .
Towards Aspectual Component-Based Development of Real-Time Systems2004In: 9th International Conference on Real-Time and Embedded Computing Systems and Applications RTCSA 2003,2003, Heidelberg: Springer Verlag , 2004, p. 558-Conference paper (Refereed)

Increasing complexity of real-time systems, and demands for enabling their configurability and tailorability are strong motivations for applying new software engineering principles, such as aspect-oriented and component-based development. In this paper we introduce a novel concept of aspectual component-based real-time system development. The concept is based on a design method that assumes decomposition of real-time systems into components and aspects, and provides a real-time component model that supports the notion of time and temporal constraints, space and resource management constraints, and composability. We anticipate that the successful applications of the proposed concept should have a positive impact on real-time system development in enabling efficient configuration of real-time systems, improved reusability and flexibility of real-time software, and modularization of crosscutting concerns. We provide arguments for this assumption by presenting an application of the proposed concepton the design and development of a configurable embedded real-time database, called COMET. Furthermore, using the COMET system as an example, we introduce a novel way of handling concurrency in a real-time database system, where concurrency is modeled as an aspect crosscutting the system.

• 46.
Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
Department of Computer Engineering, Mälardalen University, Västerås, Sweden . Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology. Department of Computer Engineering, Mälardalen University, Västerås, Sweden .
Towards aspectual component-based development of real-time systems2003In: Real-Time and Embedded Computing Systems and Applications: 9th International Conference, RTCSA 2003, Tainan City, Taiwan, February 18-20, 2003. Revised Papers / [ed] Jing Chen and Seongsoo Hong, Springer Berlin/Heidelberg, 2003, Vol. 2968, p. 558-577Chapter in book (Refereed)

Increasing complexity of real-time systems, and demands for enabling their configurability and tailorability are strong motivations for applying new software engineering principles, such as aspect-oriented and component-based development. In this paper we introduce a novel concept of aspectual component-based real-time system development. The concept is based on a design method that assumes decomposition of real-time systems into components and aspects, and provides a real-time component model that supports the notion of time and temporal constraints, space and resource management constraints, and composability. We anticipate that the successful applications of the proposed concept should have a positive impact on real-time system development in enabling efficient configuration of real-time systems, improved reusability and flexibility of real-time software, and modularization of crosscutting concerns. We provide arguments for this assumption by presenting an application of the proposed concept on the design and development of a configurable embedded real-time database, called COMET. Furthermore, using the COMET system as an example, we introduce a novel way of handling concurrency in a real-time database system, where concurrency is modeled as an aspect crosscutting the system.

• 47.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
Application-Tailored Database Systems: a Case of Aspects in an Embedded Database2004In: 8th International Database Engineering and Applications Symposium IDEAS04,2004, Los Alamitos, California: IEEE Computer Society , 2004, p. 291-Conference paper (Refereed)

Current techniques used to design and implement database systems do not provide support for efficient implementation of crosscutting concerns in the database software, e.g., failure detection, database policies such as concurrency control and scheduling, and synchronization. Aspect-oriented software development (AOSD) is a new technique that provides an efficient way of modularizing crosscutting concerns in software systems. In this paper we evaluate the effectiveness of applying AOSD to database systems thereby paving way for successful application of aspect languages to the database domain. Our focus is on embedded database systems, as a representative for a class of database systems. We show, by analyzing and re-engineering one commercial well-known embedded database system Berkeley database, that aspect-orientation has promise, especially in enabling development of tailorable, maintainable, and evolvable database systems.

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