A Qualitative Approach to Dependability Engineering

Dependability is usually defined in terms of other quality attributes such as reliability and security rather than being directly measurable. In order to design dependable systems, the architect must balance the attributes that define dependability with other quality attributes. Often these qualities have incompatible units and scales of measure. This investigation examined techniques for using qualitative reasoning to build reasoning frameworks that can accommodate measures of qualitative attributes, such as security, and quantitative values, such as reliability, to guide the architecture definition process. A technique for reasoning about these heterogeneous types of data is proposed.