Middleware Support for Adaptive Dependability

Generic middleware can often not provide satisfactory solutions, but neither is it acceptable to let the application developer reinvent the wheel each time. Therefore, middleware shall support reuse of infrastructural services while leaving the application in control. In particular, we contribute with a middleware approach to support adaptive dependability by balancing integrity and availability in distributed systems. 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 balancing 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.