An O(1) Distributed Exception Handling Mechanism for Dynamcially Reconfigurable Real-time Software

Title of Thesis: AN O(1) DISTRISBUTED EXCEPTION HANDLING MECHANISM FOR DYNAMICALLY RECONFIGURABLE REAL-TIME SOFTWARE Degree Candidate: Jun Lang Degree and Year: Master of Science, Electrical Engineering, 1997 Thesis directed by: David B. Stewart, Assistant Professor Department of Electrical Engineering With programs growing in size and complexity, the quality and cost of developing and maintaining them are still deep concerns to software industries. Dynamically reconfigurable software, which is one paradigm for using component-based software, is a promising approach in reducing the developmental cost while increasing the quality and the reliability. For real-time embedded systems, a dynamically reconfigurable real-time software paradigm provides many major advantages over conventional real-time software development techniques. As with any other real-time software, dynamically reconfigurable software needs exception detection and handling mechanisms to satisfy reliability requirements. However, the focus of developing reusable software has been on the structure of initialization and normal operation code within reusable components. This can make an application composed of reusable software non-deterministic and difficult to understand in the presence of errors. Even if 100 percent of modules are reused, there may still be the need for significant amounts of new code for error handling. Our goal is to create a structured exception handling mechanism for dynamically reconfigurable real-time software (DRRTS) that helps programmers to create reliable exception handling components that can be integrated with the main functional components. The key contributions of the work presented in this thesis include establishing functional requirements of an exception handling mechanism for DRRTS, doing a comprehensive literary survey investigating the applicability of existing exception handling technologies to DRRTS, and designing an exception handling mechanism that supports distributed and O(1) time exception handling for DRRTS. The mechanism we designed is an operating system service that targets shared memory based multi-processor multi-threading real-time computing environments. We have created a new DRRTS component which we call Exception Handling Object (EHO), which is a dynamically reconfigurable exception handling component that derives from the Port-Based Object (PBO) model as defined by the Chimera Methodology. AN O(1) DISTRIBUTED EXCEPTION HANDLING MECHANISM FOR DYNAMCIALLY RECONFIGURABLE