Middleware support for adaptive dependability

Abstract. Generic middleware can often not provide satisfactory solu-tions, but neither is it acceptable to let the application developer re-invent the wheel each time. Therefore, middleware shall support reuse of infrastructural services while leaving the application in control. In par-ticular, we contribute with a middleware approach to support adaptive dependability by balancing integrity and availability in distributed sys-tems. To achieve this goal, we add a new middleware service for explicit runtime management of data integrity constraints. In order to provide the desired balancing with respect to an application’s requirements and environment conditions, our approach supports the application developer with explicit interaction between middleware, application, and metadata. Based on our prototype implementation, we show how adaptive balanc-ing of integrity and availability improves the overall dependability. The performance impairments of our approach are typically worth their costs in systems where the read-to-write ratio is high or write performance is not a limiting factor