1. CPSC 872 John D. McGregor Session 12 Software Design, cont’d

2. Specification and design problem solution specification implementation specification

3. Requirements/Design Traceability is the concept of following the requirements through the specification into the design. Want to have associations that can change as requirements change or designs change.

4. Fault analysis Fault is an anomaly at a point in the system Error is the result of executing an instruction Fault analysis looks for typical places where faults could reside Error modeling looks at where incorrect values might flow http://www.hq.nasa.gov/office/codeq/risk/do cs/ftacourse.pdf

5. Where do errors occur? At interfaces – Hw to sw – Hw to hw In wires – Near magnets In execution – Processor overheating Logic does not spontaneously change but…

6. What goes wrong in a software- intensive system? Buffer overflows Failure to receive input in time Failure to produce output in time Data out of range Logic errors Incorrect process priorities Data visible outside of module

7. Isolette https://wiki.sei.cmu.edu/aadl/index.php/Isole tte_example#Behavior_description https://wiki.sei.cmu.edu/aadl/index.php/Isole tte_example#Behavior_description http://www.santoslab.org/pub/high- assurance/module-aadl/slides/AADL- Isolette.pdf http://www.santoslab.org/pub/high- assurance/module-aadl/slides/AADL- Isolette.pdf http://dl.acm.org/citation.cfm?id=2527271

8. Assignment Develop a Fault Tree Analysis for the OBD system Develop a Failure Modes and Effects Analysis for the OBD system Due Oct 8 by 11:59pm