Management of adaptation capability of networked systems in dynamic environments

The paper formulates methods to assess the QoS capability of a networked system S under hostile environment conditions incident on S. How good is the system S in meeting the QoS expectations of applications is analyzed in terms of the non-functional attributes of the QoS behavior of S (e.g., transaction latency & drop rate in on-line web services). A self-assessment mechanism programmed in S enables autonomic reconfiguration of the system-internal algorithmic processes & parameters to sustain an optimal behavior of S in the face of changing environment conditions. We employ PO-MDP based modeling tools to benchmark the QoS capability by stress-testing S with artificially injected environment conditions. As case study, we describe the assessment of a CDN (content delivery network) vis-a-vis the algorithmic processes for optimal placement of content caching nodes in a distribution topology to lower the content read latency and overhead experienced by clients.