Linköping Studies in Science and Technology Dissertation No. 1005 Developing Reusable and Reconfigurable Real-Time Software using Aspects and Components by Aleksandra Tešanović Department of Computer and Information Science Linköpings universitet SE-581 83 Linköping, Sweden Linköping 2006 To Goran Abstract Our main focus in this thesis is on providing guidelines, methods, and tools for de- sign, con¯guration, and analysis of con¯gurable and reusable real-time software, developed using a combination of aspect-oriented and component-based software development. Speci¯cally, we de¯ne a recon¯gurable real-time component model (RTCOM) that describes how a real-time component, supporting aspects and en- forcing information hiding, could e±ciently be designed and implemented. In this context, we outline design guidelines for development of real-time systems using components and aspects, thereby facilitating static con¯guration of the system, which is preferred for hard real-time systems. For soft real-time systems with high availability requirements we provide a method for dynamic system recon¯guration that is especially suited for resource-constrained real-time systems and it ensures that components and aspects can be added, removed, or exchanged in a system at run-time. Satisfaction of real-time constraints is essential in the real-time domain and, for real-time systems built of aspects and components, analysis is ensured by: (i) a method for aspect-level worst-case execution time analysis; (ii) a method for formal veri¯cation of temporal properties of recon¯gurable real-time components; and (iii) a method for maintaining quality of service, i.e., the speci¯ed level of performance, during normal system operation and after dynamic recon¯guration. We have implemented a tool set with which the designer can e±ciently con¯- gure a real-time system to meet functional requirements and analyze it to ensure that non-functional requirements in terms of temporal constraints and available memory are satis¯ed. In this thesis we present a proof-of-concept implementation of a con¯gurable embedded real-time database, called COMET. The implementation illustrates how our methods and tools can be applied, and demonstrates that the proposed solutions have a positive impact in facilitating e±cient development of families of real-time systems. i Acknowledgements With mixed feelings I approach the end of my PhD studies. On one hand I am very happy that I have ¯nished my thesis and will be moving onto another stage in my life, and on the other hand I am really sad for not being a student anymore. I blame the sadness on JÄorgenHansson, my supervisor. He has not only provided guidance through technical issues, but also made me feel protected, supported, encouraged, and happy during my studies. JÄorgenhas, over the years, become one of my best friends and allies. I was fortunate to do my research within the COMET project, a joint project between LinkÄopingand MÄalardalenUniversity, working alongside Dag NystrÄom and Christer NorstrÄom. Collaboration with Dag had a catalytic e®ect on my research and has also showed me that great ideas are a product of spirited and witty discussions. Christer's feedback, questions, and suggestions have helped greatly in shaping my research. ARTES, a network for real-time research and graduate education in Sweden, and CUGS, the Swedish computer science graduate school, have both provided ¯nancial support for my graduate studies, as well as given me the opportunity to meet new friends and exchange ideas. My last two years of studies would not be as interesting if I was not ¯nanced by the SAVE project. SAVE meetings and their members have shown me another, much more fun, dimension of research collabo- ration. ARTES and SAVE have been founded by the SSF, Swedish foundation for strategic research. I extend my gratitude to past and present members of RTSLAB for providing an enjoyable and lively working environment. Simin Nadjm-Tehrani has suppor- ted me gracefully through the years of my PhD studies at RTSLAB. She is also responsible for the heaviness of formal analysis that, when I was not paying atten- tion, sneaked into my thesis. The miracle woman and my friend, Anne Moe, has done wonders when it comes to helping me with administrative and other personal matters. Mehid Amirijoo and Thomas Gustafsson deserve praise for many gossip sessions and all the help they have unsel¯shly given me. United in supervision, we successfully traumatized many master's thesis students, of which a majority was working on the implementation of the COMET database platform. Calin Curescu has shown his real (soft) side and, in the last and most stressful days of thesis writing, helped out with teaching so I could focus on writing. Traveling iii iv back and forth from the SAVE meetings would not be as fun without the company of the SAVE silver member, Jonas Elmqvist, and an RTSLAB ¯ka would not be as enjoyable without the companionship of remaining RTSLAB members: Diana Szentiv¶anyi, Kalle Burbeck, Mikael Asplund, and Erik Kuiper. I also thank the merry ESLAB bunch for their hospitality in the "ESLAB corridor" and, most importantly, for keeping me up to date with all spicy events that happen in their and neighboring labs. My friends in Sweden and abroad have been great throughout all these years of my studies. I could always count on their kindness and encouragement. Love and gratitude go to my parents. To my mother, for bringing up an ambitious and stubborn daughter in the world of men, and my father, who's patience and understanding has helped me in many situations. I also thank them for getting me a great younger sister. It is a bless having a younger sibling: you at the same time get a friend, admirer, and a follower, who is, for the greater part of her life, blind to your many flaws. I think that we are all constructed out of two related opposites, positive pole and negative pole, and that the two need to be in balance for the person to be complete. I would have been incomplete without my husband, Goran. He has been and continues to be my positive pole. Without his unconditional love and encouragement I would not have been able to ¯nish this thesis. He is Neo of my Matrix. Hvala, Aleksandra Te·sanovi¶c LinkÄoping,February 2006 List of Publications This work is done as a part of the COMET research project, a joint project between LinkÄopingUniversity and MÄalardalenUniversity. The principal inve- stigators of the project are JÄorgenHansson (LinkÄopingUniversity) and Chris- ter NorstrÄom(MÄalardalenUniversity). The doctoral students in the project are Aleksandra Te·sanovi¶c(LinkÄoping)and Dag NystrÄom(MÄalardalen). The COMET project has over the years evolved and involved collaboration with addi- tional senior researchers (Mikael Nolin, MÄalardalenUniversity, and Simin Nadjm- Tehrani, LinkÄopingUniversity), and doctoral students (Mehdi Amirijoo and Tho- mas Gustafsson, both at LinkÄopingUniversity). Furthermore, several master's students have completed their thesis work by implementing or investigating spe- ci¯c issues related to the COMET project, and thereby also contributed to the research presented in this thesis; their contributions are recognized in the author lists of the papers produced within the project. The COMET project has resulted in the following published papers. Publications Included in the Thesis The contributions of this thesis are based on the following publications (the list contains descriptions of the content of each paper, relating it to the other papers, and the role of the thesis author in contributing to the paper). Data Management Issues in Vehicle Control Systems: a Case Study, Dag NystrÄom,Aleksandra Te·sanovi¶c,Christer NorstrÄom,JÄorgenHansson, and Nils-Erik Bºankestad, In Proceedings of the 14th IEEE Euromicro International Conference on Real-Time Systems (ECRTS'05), pages 249-256, IEEE Computer Society, June 2002. This paper presents 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. The paper also presents how a database could be integrated into the studied application and how the database management system could be designed to suit this particular class of systems. The paper was written based on the industrial stay at Volvo Construction Equipment Components AB, Sweden. The industrial stay, and thereby the wri- v vi ting of this case study paper, was made possible by Nils-Erik Bºankestad.Alek- sandra Te·sanovi¶cand Dag NystrÄominvestigated two di®erent real-time systems, one each. Additionally, Te·sanovi¶cstudied the impact of current data management in both systems. Integrating Symbolic Worst-Case Execution Time Analysis into Aspect-Oriented Software Development, Aleksandra Te·sanovi¶c, Dag NystrÄom,JÄorgenHansson, and Christer NorstrÄom,OOPSLA 2002 Workshop on Tools for Aspect-Oriented Software Development, November 2002. This workshop paper presents an initial proposal for providing support for predictable aspect-oriented software development by enabling symbolic worst-case execution time analysis of aspect-oriented software systems. Aleksandra Te·sanovi¶cdeveloped a way of representing temporal information of aspects and an algorithm that enables worst-case execution time analysis of aspect-oriented systems. Towards Aspectual Component-Based Development of Real-Time Systems, Aleksandra Te·sanovi¶c,Dag NystrÄom,JÄorgenHansson, and Christer NorstrÄom,In Proceeding of the 9th International Conference on Real-Time and Embedded Computing Systems and Applications (RTCSA 2003), Lecture Notes in Computer Science, vol. 2968, pp. 558-577, Springer-Verlag, 2003. This paper introduces 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, and space and resource management constraints.