Reliability Analysis and Assessment of Web Services-based System with Fault Tolerance Design

具容錯設計之網路服務系統可靠度分析與評估

王品珩(Pin-Heng Wang)

指導教授 ： 黃慶育

國立清華大學/電機資訊學院/資訊系統與應用研究所/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00539

摘要

In recent years, Service-Oriented Architecture (SOA) and cloud computing have become more and more popular. Web Services (WS) are used to build the critical system (i.e., real-time system, transaction processing system, etc.) more often. Therefore, a number of fault tolerance strategies for WSs and some WSs-based system reliability models have been proposed. However, the reliability of hardware (i.e., host, network, connection device, etc.) has not been considered in the reliability analysis of the WSs-based system with fault tolerance, and the acceptance test (AT) and the decision mechanism (DM) are usually assumed error free.
In order to obtain more accurate reliability of WSs-based fault tolerance systems, this research proposes the analysis and assessment for WSs-based system with the NVP and the RB called ENVP and ERB. A WSs-based fault tolerance system is regard as a composition of software and hardware components and the reliability of each component may affect the system reliability in different scenarios. The operation of the ENVP and the ERB are proposed, and then simulations are implemented to evaluate the system reliability and the probability that various operations will occur in the system. Finally, the reliability of different compositions of WSs and ATs are analyzed and the adaptive ENVP architecture and ERB architecture in general are proposed.

關鍵字

網路服務 ； 軟體可靠度 ； 軟體容錯

並列摘要

近年來由於大環境發展成熟，使用服務導向架構和雲端運算逐漸成為一種新趨勢。相較以往，網路服務更常被用來建構關鍵性系統，例如即時系統、交易處理系統等，因此一些針對網路服務的容錯策略和網路服務系統的可靠度模型相繼被提出。然而，以往在對於具備容錯設計的網路服務系統分析上並未考慮硬體，如主機、網路、通訊設備等的可靠度，容錯技術中使用的接受度測試軟體和決策機制也常被假設為無誤的(此種假設可能不符合實際情形)。
為了更精確地評估網路服務容錯系統的可靠度，本研究針對此種系統提出一套可靠度的分析與評估方法，以ENVP和ERB兩種架構進行說明及分析。我們認為分析一個網路服務容錯系統的可靠度時，需考慮其中軟體和硬體元件的組成，以及這些元件的運作情形對於整體系統可靠度的影響。本研究說明了ENVP和ERB架構的運作情形，並模擬系統運作以獲得各種運作情形發生的機率和系統可靠度。最後針對數種ENVP和ERB組合進行可靠度分析，並提出適用於一般情形的ENVP和ERB架構。

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