User-oriented and -perceived software availability measurement and assessment with environmental factors

This paper proposes the methods of the operation-oriented software availability measurement and assessment. Considering the difference of the software failure-occurrence phenomena and the restoration characteristics between the testing and the operation phases, we first introduce the environmental factors into the existing Markovian software availability model. Next we discuss the stochastic modeling for measuring software service availability; this is one of the customer-oriented attribute and defined as the attribute that the software system can successfully satisfy the end users' requests. We derive several service-oriented software availability assessment measures which are given as the functions of time and the number of debuggings. Finally, we present several numerical examples of these measures for software service availability analysis.