Survivability models and implementations in large distributed environments

As information systems have become ever more complex, the interdependence of these systems has increased; consequently, the issue of survivability has also become increasingly complicated. The need for survivability is most pressing for mission-critical systems, especially when they are integrated with commercial off-the-shelf (COTS) products or services. In the paper, we identify two survivability models - static and dynamic - and we discuss their trade-offs. The comparison of these trade-offs between the models resulted in the creation of a new hybrid survivability model that provides more robust survivability services than the static or dynamic models can provide by themselves. To prove the feasibility of our ideas, we describe our implementation of each of the three survivability models in the context of a mission-critical banking system in a distributed computing environment. Finally, we discuss the lessons we learned from our implementations.