Applying software failure modes and effects analysis to interfaces

Software failure modes and effects analysis (SFMEA) is sometimes applied to new mission-critical and safety-critical system development. This kind of analysis, like its older cousin Hardware FMEA (HFMEA), tries to determine all possible types of failure for each component, one by one, and attempts to predict system-level effects for each failure. While software variables and classes don't fail in the sense that hardware fails, variables do sometimes assume unexpected values [1] and class methods don't always perform as expected.