A comparative study of exception handling mechanisms for building dependable object-oriented software

Modern object-oriented systems have to cope with an increasing number of exceptional conditions and incorporate fault tolerance into systems' activities in order to meet dependability-related requirements. An exception handling mechanism is one of the most important schemes for detecting and recovering errors, and for structuring fault-tolerant activities in a system. The mechanisms that were ill designed can make an application unreliable and difficult to understand, maintain and reuse in the presence of faults. This paper surveys various exception mechanisms implemented in different object-oriented languages, evaluates and compares different designs. A taxonomy is developed to help address 10 basic technical aspects for a given exception handling proposal, including exception representation, external exceptions in signatures, separation between internal and external exceptions, attachment of handlers, handier binding, propagation of exceptions, continuation of the control flow, clean-up actions, reliability checks, and concurrent exception handling. Practical issues and difficulties are summarized., major trends in actual languages are identified, and directions for future work are suggested. (C) 2001 Elsevier Science Inc. All rights reserved.