Despite advances in software engineering, software faults continue to cause system downtime. Software faults are difficult to detect before the system fails, especially since the first symptom of a fault is often system failure itself.This paper presents a computational geometry technique and a supporting tool to tackle the problem of timely fault detection during the execution of a software application. The approach involves collecting a variety of runtime measurements and building a geometric enclosure, such as a convex hull, which represents the normal (i.e., non-failing) operating space of the application being monitored. When collected runtime measurements are classified as being outside of the enclosure, the application is considered to be in an anomalous (i.e., failing) state. This paper presents experimental results that illustrate the advantages of using a computational geometry approach over the distance based approaches of Chi-Squared and Mahalanobis distance. Additionally, we present results illustrating the advantages of using the convex-hull enclosure for fault detection in favor of a simpler enclosure such as a hyperrectangle
The transmission of voice-over-Internet protocol (VoIP) network traffic is used in an increasing variety of applications and settings. Many of these applications involve communications where VoIP systems are deployed under unpredictable conditions with poor network support. These conditions make it difficult for users to configure and optimize VoIP systems and this creates a need for self configuring and self optimizing systems. To build an autonomic system for VoIP communications, it is valuable to be able to measure the user perceived utility of a system. In this paper we identify factors important to the estimation of user perceived utility in task dependent VoIP communications.
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