Extending conventional languages by distributed/concurrent exception resolution

The state of art in handling and resolving concurrent exceptions is discussed and a brief outline of all research in this area is given. Our intention is to demonstrate that exception resolution is a very useful concept which facilitates joint forward error recovery in concurrent and distributed systems. To do this, several new arguments are considered. We understand resolution as reaching an agreement among cooperating participants of an atomic action. It is provided by the underlying system to make it unified and less error prone, which is important for forward error recovery, complex by nature. We classify atomic action schemes into asynchronous and synchronous ones and discuss exception handling for schemes of both kinds. The paper also deals with introducing atomic action schemes based on exception resolution into existing concurrent and distributed languages, which usually have only local exceptions. We outline the basic approach and demonstrate its applicability by showing how exception resolution can be used in Ada 83, Ada 95 (for both concurrent and distributed systems) and Java. A discussion of ways to make this concept more object-oriented and, with the help of reflection, more flexible and useful, concludes the paper.