Risk Assesment

Risk Assessment and performability Analysis of Software Systems Specifications

"Risk Assessment of Functional Specification of Software Systems Using Colored Petri Nets,"
Proceedings of the International Symp. On Software Reliability Engineering (ISSRE'97), IEEE Comp. Soc.,
November 1997.
This paper presents an example of risk assessment in complex real-time software systems at the early stages of development. A heuristic risk assessment technique based on Colored Petri Nets (CPN) Models is used to classify software according to their relative importance in terms of such factors as severity and complexity. The methodology of this technique is presented in a companion paper in [1]. This technique is applied on the Earth Operation Commanding Center (EOC _COMMANING); a large component of NASA’s Earth Observing System (EOS) project. Two specifications of the system are considered: a sequential model and a pipeline model. Results of applying the above technique to both CPN-based models yield different complexity measures. The pipeline model shows clearly a higher risk factor than the sequential model. Whereas using traditional complexity measures, the risk factors were similar in both
models. components with high risk factor which would require the development of effective fault tolerance mechanisms.
A Methodology for Risk Assessment and Performability Analysis of Large Scale Software Systems
International Conferance on Engineering Mathematics and Physics. Cairo Egypt, Dec, 1997
(PDF file,95k)
This paper describes a methodology for modeling and analysis of large scale software specifications of concurrent real-time systems. Two types of analysis, namely, risk assessment and performability analysis are presented. Both types of analysis are based on simulations of Colored Petri Nets (CPN) software specification models. These CPN models are mapped from the software specifications originally developed using Computer-Aided Software Engineering (CASE) tools. Thus the methodology lends itself to a three step process. In the first step CASE based models are mapped to the CPN notation. The CPN models are completed for scenario based simulations in the second step. Finally in the third step the models are simulated for risk assessment and performability analysis. A model of a large industrial scale software
specifications is presented to illustrate the usefulness of this approach. The model is based on a component of NASA’s Earth Observing System (EOS).
A Methodology For Risk Assessment of Functional Specification of Software Systems Using Colored Petri
Nets
International Symp. on Software Metrics, IEEE Computer Soc., Nov. 1997
(Word Doc file,95k)
This paper presents a methodology for risk assessment in complex real-time software systems at the early stages of development, namely the analysis/design phase. A heuristic risk assessment technique is described based on Colored Petri Nets (CPN) Models. The technique uses complexity metrics and severity measures in developing a heuristic risk factor from software functional specifications. The objective of risk assessment is to classify the software components according to their relative importance in terms of such factors as severity and complexity. Both traditional static and dynamic complexity measures are supported. Concurrency complexity, is presented as a new dynamic complexity metric. This metric measures the added dynamic complexity due to concurrency in the system. Severity analysis is conducted using failure mode and effect analysis (FMEA).
Performability Analysis of the Commanding Component of NASA’s Earth Observing System
The 10th International Conf. on Parallel and Distributed Computing, New Orleans, Oct. 1997
(PDF file,26k)
The objective of this work is to develop methods and techniques for generating verification and analysis models from notations used for Parallel and Distributed Systems specifications. The resulting verification models can be subjected to extensive and exhaustive verification of the requirement specifications. This paper presents an application of the methodology developed by us to integrate a CASE environment based on SART (Structured Analysis with Real Time) notation and CPN (Coloured Petri Nets) based verification environment.