貝式網路為基礎的商業級軟體組件決策評估研究

BBN-based decision making for adoption of COTS in nuclear safety systems

黃鈺綺(Yu-Chi Huang)

指導教授 ： 范金鳳

元智大學/資訊學院/資訊工程學系/碩士(2011年)

摘要

在軟體重用(reuse)的趨勢下，因商業級軟體組件(COTS)擁有縮短開發時程、降低開發成本及具有運轉經驗的優勢，有愈來愈多業者以商業級軟體組件(COTS)為基礎發展數位系統。COTS不像許多安全關鍵軟體，在開發過程並未針對特定應用領域，嚴格依循特定領域法規或標準，因此使用COTS發展安全關鍵系統的評估要求各有不同。可恃性(Dependability)是軟體獨有的特性，缺乏具體及可量化的評估證據，目前多採用檢核清單的方式，由評估者勾選評估要項是否符合需求，再透過其他討論決定該COTS的符合性，該評估方法對於具有不確定因素的軟體特性恐有遺漏。

本研究提出基於貝式網路(BBN-based)的COTS決策評估方案，以EPRI-106439核電廠安全相關系統應用商業級數位系統的評估與允收指引為例，首先對評估指引進行軟體關鍵特性分析，建立COTS BBN，並透過BBN提供圖形化的表達方式與對不確定事件的推論特性，協助使用者以量化且客觀的方式評估COTS的可恃性，有助於提高決策品質。

關鍵字

商業級軟體組件 ； 可恃性 ； 貝式信心網路

並列摘要

In the trend of software reuse, more and more software development vendors develop digital systems based on Commercial off-the Shelf software (COTS) due to the advantages of shortened development time, reduced costs, and past operating experience. However, unlike safety critical software, COTS did not strictly follow specific regulations or standards during development. Using COTS in safety critical systems has different requirements such as safety and dependability. Yet, such quality attributes are hard to obtain quantifiable assessment evidence. Evaluators usually use “reviews and checklists” to assess the dependability of the system. This approach may be controversial and may miss some important requirements for software, in which uncertainty is its intrinsic nature.

We proposed a BBN-based decision making technique for adoption of COTS following EPRI-106439 requirements. EPRI-106439 is a guideline for evaluation and acceptance of commercial grade digital equipment for nuclear safety application. First, we analyzed software critical characteristics of EPRI-10643. Then we proposed a COTS BBN. Through BBN, with graphical presentation and reasoning under uncertainties, our approach can help evaluators to assess the dependability of COTS with a quantified and objectively manner to improve decision quality.

並列關鍵字

Commercial off-the Shelf ； COTS ； Dependability ； BBN

參考文獻

[1] EPRI TR-106439, Guideline on Evaluation and Acceptance of Commercial Grade Digital Equipment for Nuclear Safety Applications, October 1996.

[2] DO-178B/ED-12B, Software Considerations in Airborne Systems and Equipment Certification, December 1, 1992.

[3] Abdallah Mohamed, Guenther Ruhe, Armin Eberlein, COTS Selection: Past, Present, and Future, in Proceedings of 14th Annual IEEE International Conference and Workshops on the Engineering of Computer-Based Systems (ECBS'07), 2007.

[4] Ljerka Beus-Dukic, Non-Functional Requirements for COTS Software Components, in Proceedings of ICSE workshop on COTS Software, 2000.

[5] Martin Neil, Bev Littlewood and Norman Fenton, Applying Bayesian belief networks to systems dependability assessment, in Proceedings of 4th Safety Critical Systems Symposium, Springer Verlag, 1996.