Planning the transformation of overlays

Reconfiguring a topology is an important technique to sustain high efficiency and robustness of an overlay. However, the problem of transforming the overlay from an old topology to a newly refined one, at runtime, has received relatively little attention. The key challenge is to minimize the disruption that can be caused by topology transformation operations. Excessive disruption can be costly thus hamper the decision to migrate to a better topology. To address this issue, we solve a problem of finding an appropriate sequence of steps to transform a topology that incurs the least service disruption. We call this the incremental topology transformation (ITT) problem. ITT can be formulated well as an automated planning problem and can be solved with numerous off-the-shelf planning algorithms. However, we found that state-of-the-art domain-independent planning techniques can not scale to solve large ITT problem instances. This shortcoming motivated us to develop a suite of planners that use novel domain-specific heuristics to guide the search for a solution. Our empirical evaluation shows that our planners offer a viable solution to a diversity of ITT problems.