Tinkertoy Tower Design

Tinkertoy Tower Design

Post Mortem DiscussionPost Mortem Discussion

The point of the exerciseThe 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)

Design phaseDesign 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

Implementation phaseImplementation 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

Operations phaseOperations 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

Construct Figures of MeritConstruct Figures of Merit

All choices are trade-offsAll choices are trade-offs

Schedule always mattersSchedule always matters

Prototypes must pass tests

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

Discovering requirementsDiscovering requirements

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

Design lifeDesign 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

Analyze RisksAnalyze 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?

Implementation IssuesImplementation 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

All design is evolutionary 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?

Not applicable to software?

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

The essence of Systems 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