The Recovery Language Approach

Abstract

After having discussed the general approach of fault-tolerance languages and their main features, the focus is now set on one particular case: The ARIEL1 recovery language. It is also described as an approach towards resilient computing based on ARIEL and therefore dubbed the “recovery language approach” (ReL). In this chapter, first the main elements of ReL are introduced in general terms, coupling each concept to the technical foundations behind it. After this a quite extensive description of ARIEL and of a compliant architecture are provided. Target applications for such architecture are distributed codes, characterized by non-strict real-time requirements, written in a procedural language such as C, to be executed on distributed or parallel computers consisting of a predefined (fixed) set of processing nodes. The reason for giving special emphasis to ARIEL and its approach is not in their special qualities but more on the fact that, due to the first-hand experience of the author, who conceived, designed, and implemented ARIEL in the course of his studies, it was possible for him to provide the reader with what may be considered as a sort of practical exercise in system and fault modeling and in application-level fault-tolerance design, recalling and applying several of the concepts introduced.