4. Real-time Operating Systems

by Peter Puschner (Technische Universität Wien, Austria)

Link to the SOTA Chapter

Ongoing Research

In recent developments one can find a trend towards smart (re)programmable devices (PDAs, mobile phones, etc.) that can be adapted to the users needs by replacing software modules or adding new ones. In order to execute code of applications on a variety of different platforms, the portability of code is of highest importance. The demand for portability and the need for real-time responsiveness gave rise to a whole new stream of reasearch in the area of real-time Java. The main activities towards building run-time environments for real-time embedded systems were initiated by Sun. The real-time specification for Java (RTSJ) [Bollella 2000a, Bollella 2000b] attempts to define a real-time Java environment that can be realized with minimal modifications to the original Java semantics [Gosling 2000]. Subsets of the RTSJ for high-integrity systems have been proposed in [Puschner 2001, Kwon 2002]. The second strong development besides the real-time Java efforts is in direction of real-time middleware. In this direction the research on real-time Corba [OMG 1998], but also other approaches [Kim 1999] are notable.

Future Directions

In the near future, networked systems and operating systems will become even more important. Therefore, composability will be a central property of future real-time networks and systems (both large systems and small devices). Clearly, composability is only achievable if the necessary operating system and middleware support is provided. To facilitate this, appropriate specifications of composable real-time interfaces are needed [Kopetz 2001].

CaberNet Related Activities

• Analysis and Implementation of a System for Parameters Measuring and Operation Controlling of Automotive Diesel Engines

• Universidad Politécnica de Valencia, Spain

The objective of this project is to design an open architecture for the control of a diesel engine in a benchmark laboratory.

• DEAR-COTS

  • Instituto Politécnico do Porto, Portugal

  The main purpose of the DEAR-COTS project (funded by the Portuguese government - PRAXIS/P/EEI/14187/1998) was the specification of an architecture based on the use of commercial off-the-shelf (COTS) components, able to support distributed computer controlled systems where reliability and timeliness are major requirements. The group's involvement in the project allowed to contribute with studies and protocols for fault-tolerance in CAN networks [Pinho 2001], and to provide a transparent framework for the replication of hard real-time applications [Pinho 2002].

• FIRST (Flexible Integrating Scheduling Technology)

  • Malardalen University, Sweden
    

  The objective of the proposed research is to develop a real-time scheduling framework for applications demanding various types of tasks, constraints, and scheduling paradigms within the same system. The FIRST project will investigate the following issues:

  • co- operation and coexistence of standard real-time scheduling schemes, time- triggered and event-triggered, dynamic and fixed priority based, as well as off-line based.
  • integration of different task types such as hard and soft, or more flexible notions, e.g., from control or quality-of- service demands, and fault-tolerance mechanisms
  • temporal encapsulation of subsystems in order to support the composability and reusability of available components including legacy subsystems
  • monitoring and maintenance of control systems over the Internet.

  
  FIRST will provide functionality for the schemes for POSIX compliant operating systems, including monitoring and maintenance of control systems over the Internet.

• High-Security Real Time Distributed System: Mobile Robot Control Application

• Universidad Politécnica de Valencia, Spain
• Universitat Politècnica de Catalunya, Spain
  

The objective of this project is to develop a distributed fault tolerant architecture for a mobile robot control. This architecture uses a vision and a wireless subsystem and motion control subsystem interconnected by a fibre optics area network (CAN).

• HYSYS (Modular Design of Hybrid Systems)

  • Universität Dortmund

  The approach concentrates on the formal development of real-life hybrid technical systems. A specification technique for the formal design, analysis, and verification of continuous-discrete models is developed which, particularly, facilitates the modular development of distributed process control software.

• REMUNE (Advanced REal-time MUlti-media and Networking Execution Platform and Development Environment)

• Ecole Polytechnique Fédérale de Lausanne, Switzerland

REMUNE is a European IST project (IST-2000-65002). The main goal of REMUNE is to develop and validate through industrial test-beds an advanced Real-Time Operating System and Development Environment (RTOS) supporting multimedia and networking services for embedded systems and product-services.

• SISTER

  • Instituto Politécnico do Porto, Portugal

  The SISTER project (funded by the American-Portuguese Development Foundation - FLAD 471/97) main goals were to stimulate research in the broad area of Real-Time Systems, and to support pos-graduation (mainly PhD) of the group elements. Within this project, the group developed computational models and tools to guarantee fault-tolerant real-time communication in distributed computer-controlled systems, based in industrial communication networks, such as PROFIBUS [Tovar 1999b], P-NET [Tovar 1999a] or CAN [Pinho 2000].

References

[Bollella 2000a] G. Bollella et al. The Real-Time Specification for Java. Addison Wesley. 2000.

[Bollella 2000b] G. Bollella, and J. Gosling. "The Real-Time Specification for Java". IEEE Computer 33(6). June 2000.

[Gosling 2000] J. Gosling, B. Joy, G. Steele, and G. Bracha. The Java Language Specification. 2nd edition. Addison Wesley. 2000.

[Kim 1999] K. Kim. "Group Communication in Real-time Computing Systems: Issues and Directions". Proceedings of the 7th IEEE Workshop on Future Trends of Distributed Computing Systems. 1999.

[Kopetz 2001] H. Kopetz. "The Temporal Specification of Interfaces in Distributed Real-Time Systems". Proceedings of the EMSOFT Conference. 2001.

[Kwon 2002] J. Kwon, A. Wellings, and S. King. Ravenscar-Java: A High Integrity Profile for Real-Time Java. Technical Report YCS 342. University of York. York, UK. 2002.

[OMG 1998] OMG. Real-Time Corba. OMG Technical Document ORBOS/98-10-05. 1998.

[Pinho 2000] L. Pinho, F. Vasques, and E. Tovar. "Integrating Inacessibility in Response Time Analysis of CAN Networks". Proceedings of the 3rd IEEE International Workshop on Factory Communication Systems (WFCS'2000). Porto, Portugal. Setember 2000. pp. 77-84.

[Pinho 2001] L. Pinho, F. Vasques."Timing Analysis of Reliable Real-Time Communication in CAN Networks". Proceedings of the 13th Euromicro Conference on Real-Time Systems. Delft, Netherlands. June 2001. pp. 103-112.

[Pinho 2002] L. Pinho, F. Vasques. "Transparent Environment for Replicated Ravenscar Applications". Proceedings of the 7th International Conference on Reliable Software Technologies - Ada-Europe 2001. Vienna, Austria. June 2002.

[Puschner 2001] P. Puschner, and A. Wellings. "A Profile for High-Integrity Real-Time Java Programs". Proceedings of the 4th IEEE International Symposium on Object-oriented Real-time Distributed Computing. 2001.

[Tovar 1999a] E. Tovar, F. Vasques, and A. Burns. "Supporting Real-Time Distributed Computer-Controlled Systems with Multi-hop P-NET Networks". Control Engineering Practice 7(8). Pergamon, Elsevier Science. August 1999. pp. 1015-1025.

[Tovar 1999b] E. Tovar, and F. Vasques."Real-Time Fieldbus Communications Using Profibus Networks". IEEE Transactions on Industrial Electronics 46(6). December 1999. pp. 1241-1251.

Maintained by Rogério de Lemos (r.delemos@ukc.ac.uk)
Last updated 4 November, 2002