This paper presents a new model for exception handling, called the replacement model. The replacement model, in contrast to other exception-handling proposals, supports all the handler responses of resumption, termination, retry, and exception propagation, within both statements and expressions, in a modular, simple, and uniform fashion. The model can be embedded in any expression-oriented language and can also be adapted to languages which are not expression oriented with almost all the above advantages. This paper presents the syntactic extensions for embedding the replacement model into Algol 68 and its operational semantics. An axiomatic semantic definition for the model can be found in [271. Categories and Subject Descriptors: D.3.3 [Programming Languages]: Language Constructsabstract

this article differentiate the exception-handling needs of CB-RTS as compared to other software paradigms and can serve as a driving force for future research into exception-handling technology.

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. How-ever, 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