1. Tinkertoy Tower Design Post Mortem Discussion

2. The point of the exercise  “It is your job to discover the system requirements.”  Who is the customer?  Exercise consists of 2 phases:  Design (40 minutes)  Implementation (15 minutes)  “It is your job to discover the system requirements.”  Who is the customer?  Exercise consists of 2 phases:  Design (40 minutes)  Implementation (15 minutes)

3. Design phase  Planning (problem & solution)  Classes of components  Deliverables are a design and its inventory of technologies  Finding & fixing issues cheap  Deadline (40 min)  Penalty (large)  Bonus (smaller)  Ends with PDR  Planning (problem & solution)  Classes of components  Deliverables are a design and its inventory of technologies  Finding & fixing issues cheap  Deadline (40 min)  Penalty (large)  Bonus (smaller)  Ends with PDR

4. Implementation phase  Build  Specific components (objects)  Deliverable is a prototype  Must pass system test  Resolve unplanned issues  but at a steep cost  Deadline (15 min)  Penalty (absolute)  Bonus (large)  Ends with CDR  Build  Specific components (objects)  Deliverable is a prototype  Must pass system test  Resolve unplanned issues  but at a steep cost  Deadline (15 min)  Penalty (absolute)  Bonus (large)  Ends with CDR

5. Operations phase  Not addressed in exercise  Customer will operate  Design must address maintenance and other life cycle issues  Never ends  The clearer the milestones between phases, the better  Not addressed in exercise  Customer will operate  Design must address maintenance and other life cycle issues  Never ends  The clearer the milestones between phases, the better

6. Construct Figures of Merit

7. All choices are trade-offs

8. Schedule always matters

9. Prototypes must pass tests  Include cost of test equip.  Environment is described  Flat hard surface  Free standing  Minimum test is stated, but  Additional requirements are always present  Include cost of test equip.  Environment is described  Flat hard surface  Free standing  Minimum test is stated, but  Additional requirements are always present

10. Discovering requirements

11. Design life  Implicit in every project  Should be explicitly stated  Y2K was a design life issue  Observatory systems can have an especially long life  STB running since 20 July 1993  Lifecycle planning  Retirement requirements  Evolving environments  Implicit in every project  Should be explicitly stated  Y2K was a design life issue  Observatory systems can have an especially long life  STB running since 20 July 1993  Lifecycle planning  Retirement requirements  Evolving environments

12. Analyze Risks  Unprecedented challenges  Software projects are notorious for collapsing under own weight  Either a project is tied to core mission of the organization or  It isn’t - which is riskier?  Unprecedented challenges  Software projects are notorious for collapsing under own weight  Either a project is tied to core mission of the organization or  It isn’t - which is riskier?

13. Implementation Issues  Different technologies have different acquisition costs  Different recurring costs  Integration issues  Quality assurance  Maintenance and reliability  Availability of HW/SW/personnel  Different technologies have different acquisition costs  Different recurring costs  Integration issues  Quality assurance  Maintenance and reliability  Availability of HW/SW/personnel

14. All design is evolutionary  Improve Tinkertoy exercise?  Display example tower?  “Here is a 60’ tower. It earns minus $33K. Why?”  Swap designs w/ other teams?  Hand out requirements with less prodding from teams?  One shared can of Tinkertoys during design phase?  Improve Tinkertoy exercise?  Display example tower?  “Here is a 60’ tower. It earns minus $33K. Why?”  Swap designs w/ other teams?  Hand out requirements with less prodding from teams?  One shared can of Tinkertoys during design phase?

15. Not applicable to software?  The tower exercise is only a cartoon model of real towers  No civil engineering, per se  No beams or trusses  No welds or rivets  No tension or compression  The tower exercise is only a cartoon model of real towers  No civil engineering, per se  No beams or trusses  No welds or rivets  No tension or compression

16. The essence of Systems  System engineering is responsible for identifying and satisfying the life cycle requirements.  One problem  Many solutions  System engineering is responsible for identifying and satisfying the life cycle requirements.  One problem  Many solutions