Adapting Web Services to Maintain QoS Even When Faults Occur

Abstract

Abstract-The paper addresses the problem of maintaining the quality of service (QoS) of an orchestration of Web services (WS), which can be affected by exogenous events (i.e., faults). The main challenge in dealing with this problem is that typically the service where a failure is detected is not the one where a fault has occurred: faults have cascade effects on the whole orchestration of services. The paper presents a novel methodology to treat the problem that is not based on Web service (re)composition, but on an adaptive re-execution of the original orchestration. Specifically, an orchestrator Manager exploits an abstract representation of the whole orchestration and a diagnostic module to localize the source of the detected failure. Then, the Manager drives the re-execution of the orchestration by deciding which service activities can be skipped, and which others must be re-executed.

Composite Service Reselection Method in Correlation Context

“…The first experiment aims at comparing two composite service initial selection methods on computation cost and quality: the integer programming algorithm based on correlated tasks (simply called IP-CT), and the general integer programming algorithm IP (such as, Marie, Roberto et al 2013). For the latter algorithm, tasks t 1 , t 2 and t 3 are regarded as independent tasks, the number of their candidate services also set to 40.…”

“…When a large deviation from estimated values and actual running status is monitored, then the slice of the service workflow that still has to be executed will be determined, simply referred to as rebinding slice (Gerardo, Massimiliano et al 2008). In finally, a new execution plan will be revised for the rebinding slice at runtime according to the current execution status (i.e., the actual QoS delivered by successfully completed services) (Danilo and Barbara et al 2007;Lina, Simon et al 2013;Marie, Roberto et al 2013).…”