Automatic Synthesis of SRN Models from System Operation Templates for Availability Analysis

Abstract

In order to cost-effectively verify whether system designs of information systems satisfy availability requirements, it is reasonable to utilize a model-based availability assessment of system design containing administrative operation procedures and a system configuration, because it does not require installing and testing in a real environment. However, since the model-based availability assessments typically require special expertise in mathematical modeling, it would be difficult for a practical system designer to build a correct availability model to assess his/her system design. Although there have been several methods to automatically synthesize the availability model from widely-used design description languages, the synthesized models do not capture impacts caused by operations in operation procedures on availability. To address this issue, this paper proposes a method to automatically synthesize an availability model in the form of stochastic reward net (SRN) from Systems Modeling Language (SysML) diagrams to specify operation procedures and system configurations. Modeling all the features of individual operations is impractical because the amount of required information in SysML diagrams input by system designers becomes larger as the number of features increases. To design the availability models with a smallest possible number of features, we classify typical availability-related features of operations into operation templates. The feasibility of the proposed method is studied by a case study based on a real system of a local government. We succeeded in synthesizing the availability models from the SysML diagrams based on an operation procedure and system configuration of the real system, and analyzing the synthesized availability models with an existing model analysis tool.