From Local Impact Functions to Global Adaptation of Service Compositions
L. Rosa, L. Rodrigues, A. Lopes, M. Hiltunen, and R. Schlichting
Proceedings of the the 11th International Symposium on Stabilization,
Safety, and Security of Distributed Systems (SSS 2009), Lyon,
France, November 3-6, 2009.
The problem of self-optimization and adaptation in the context
of customizable systems is becoming increasingly important
with the emergence of complex software systems and unpredictable
execution environments. Here, a general framework for automatically
deciding on when and how to adapt a system whenever it deviates from
the desired behavior is presented. In this framework, the adaptation
targets of the system are described in terms of a high-level policy
that establishes goals for a set of performance indicators.
The decision process is based on information provided independently for
each service that describes the available adaptations, their impact on
performance indicators, and any limitations or requirements. The
technique consists of both offline and online phases. Offline, rules are
generated specifying service adaptations that may help to achieve the
specified goals when a given change in the execution context
occurs. Online, the corresponding rule is evaluated when a change occurs
to choose which adaptations to perform.
Experimental results using a prototype framework in the context of
a web-based application demonstrate the effectiveness of this approach.
Also available extended report (pdf) .