Multi-level modeling approach for the availability assessment of e-business applications

This paper defines a multi-level modeling approach for availability assessment of e-business applications, based on two main steps: 1) hierarchical description of the system and its interactions with the users, from the functional and structural points of view, and 2) hierarchical construction and solution of the availability models based on information from the first step. Four modeling abstraction levels are considered. The highest level (user level) describes the availability of the e-business application as perceived by the users. Intermediate levels describe the availability of functions and services provided to the users. The lowest level describes the availability of the component systems on which functions and services are implemented. The availability measures of a given level are computed based on the measures provided by the immediately lower level.