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Performability Modeling with UltraSAN
September/October 1991 (vol. 8 no. 5)
pp. 69-80

The utility of stochastic activity networks (SANs) for performability evaluation is discussed. UltraSAN, a new graphical, X-Windows-based software package that uses SANs, is described. UltraSAN incorporates three innovations: a class of SAN-level performability variables common to both analytical and simulation solution methods, methods that use the performability-variable choice and the SAN structure to greatly reduce the size of the stochastic process required for an analytical solution, and methods that use the performability-variable choice and the SAN structure to reduce the number of activities checked on each state change, thus speeding the simulation. The UltraSAN modeling framework, organization, and user interface are examined. Model construction and solution are described.

Index Terms:
performability modelling; graphical software package; stochastic activity networks; performability evaluation; UltraSAN; X-Windows-based software package; performability variables; stochastic process; state change; user interface; graphical user interfaces; performance evaluation; Petri nets; stochastic processes
Joseph A. Couvillion, Roberto Freire, Ron Johnson, W. Douglas Obal, M. Akber Qureshi, Manish Rai, William H. Sanders, Janet E. Tvedt, "Performability Modeling with UltraSAN," IEEE Software, vol. 8, no. 5, pp. 69-80, Sept.-Oct. 1991, doi:10.1109/52.84218
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