Supporting coordinated adaptation in networked systems

Summary form only given. Our position is that the true potential of adaptation can only be realized if support is provided for more general solutions, including adaptations that span multiple hosts and multiple system components, and algorithmic adaptations that involve changing the underlying algorithms used by the system at runtime. Such a general solution must, however, address the difficult issues related to these types of adaptations. Adaptation by multiple related components, for example, must be coordinated so that these adaptations work together to implement consistent adaptation policies. Likewise, large-scale algorithmic adaptations need to be coordinated using graceful adaptation strategies in which as much normal processing as possible continues during the changeover. Here, we summarize our approach to addressing these problems in Cactus, a system for constructing highly-configurable distributed services and protocols.