Links to document based files:

• Entire Document (196 pages, 669 KBytes)
• Document in pieces
  • Title, Table of Contents, List of Illustrations, List of Abbreviations and Acronyms, Abstract, and Acknowledgments (16 pages, 21 KBytes)
  • Chapter 1: Introduction (6 pages, 10 KBytes)
  • Chapter 2: A Review of Related Research (12 pages, 21 KBytes)
  • Chapter 3: Port-Based Objects (34 pages, 142 KBytes)
  • Chapter 4: Software Assembly (18 pages, 32 KBytes)
  • Chapter 5: Multiprocessor Real-Time Communication (32 pages, 74 KBytes)
  • Chapter 6: Real-time Scheduling for Reconfigurable Systems (40 pages, 263 KBytes)
  • Chapter 7: Generic Hardware/Software Interfaces (18 pages, 35 KBytes)
  • Chapter 8: Fault Detection and Handling (4 pages, 9 KBytes)
  • Chapter 9: Summary, Contributions, and Future Research (4 pages, 7 KBytes)
  • Appendix and Bibliography (12 pages, 20 KBytes)

Abstract

Development time and cost of software for real-time multi-sensor based systems can be significantly reduced by reusing software from previous applications. With today's systems, however, even if some software is reused, a large amount of new code is still required to create the "glue" which integrates modules created by programmers at different sites.

In this dissertation, the design and analysis of reconfigurable real-time software which supports a software assembly paradigm is presented. The primary contributions of the work are a framework based on modelling software modules as dynamically reconfigurable port-based objects; and the identification, design, and implementation of operating system services required to support the new paradigm.

A port-based object combines the design of software using objects with the use of the port-automata theory for formally modelling concurrent processes. Each object executes asynchronously, and has a predefined set of methods. Communication with other objects occurs only through its ports, which are implemented as state variables within a distributed shared memory hardware environment. The operating system services that have been designed and implemented to support the integration of reconfigurable port-based objects without the need for writing or generating new glue code include a global state variable communication mechanism, multiprocessor subsystem control, automatic task profiling, reconfigurable device drivers, global error handling, and external subsystem interfaces.

In order to support the real-time scheduling of these dynamically reconfigurable task sets, a mixed-priority algorithm has been developed which combines the advantages of the rate monotonic and earliest-deadline-first algorithms, and provides improved support of aperiodic servers and guarantees for soft real-time tasks.

Our reconfigurable software has been demonstrated in a joint Sandia National Laboratory and Carnegie Mellon University virtual laboratory demo, and is already being used by several institutions including NASA's Jet Propulsion Laboratory, Wright Patterson Air Force Base, and NIST (National Institute of Standards and Technology).