Recent technological advances have made it possible to design bandwidth demanding distributed interactive multimedia applications such as the World Opera application. In this application artists from different opera houses across the globe, can participate in a single united performance and interact almost as if they were co-located. One of the main design challenges in this application domain is to determine the composition of system components necessary to satisfy the desired quality of

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... e in presence of failures and budget constraints. This challenge is exacerbated by the fact that quality of service depends on a multitude of factors such as human perception of video and audio, the type of audience, performance elements, etc. These factors cannot be captured by traditional approaches for dependability evaluation such as reliability, i.e., continuous delivery of correct service. This calls for developing a more comprehensive "Quality of Experience" concept. In this paper, we propose a novel method to assess the quality of experience in presence of failures, based on a new metric called perceived reliability. This method can help the system designers and engineers compare architectural variants and to determine the dependability budget. We show the feasibility of our method by applying it to a World Opera performance. Our experimental results provide useful guidelines for system engineers towards improving the quality of experience of World Opera performances despite presence of failures.