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Abstract
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As the use of web services is growing, there is an
increasing demand for dependability of these services in
business-critical applications. In this paper we introduce
various proposals for dependable web services. The existing
solutions are divided into two categories: fault tolerance
techniques, such as active and passive replications, and the use
of design diversity. The main contribution of this paper is the
use of design diversity techniques and web services business
process execution language (WS-BPEL), which would result
in proposing a useful and flexible architecture for dependable
web services. The proposed architecture has been used as the
basis of the proposed design pattern for dependable web
services, called D3WS. We have implemented the proposed
architecture in a prototype application using N-version
programming (NVP) and N-self-checking programming
(NSCP) techniques. We have also modeled the architecture
using stochastic reward nets (SRNs) for further evaluation of
dependability measures. The proposed architecture, prototype
implementation, the SRN model and the results of its
evaluation are presented in this paper.
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