the empirical process at agile india 2012

The Empirical Process

- at the very core of agile everything

Daniel Brolund @danielbrolund [email protected]

mailto:[email protected]




Daniel Brolund — @danielbrolund — [email protected]

Lets start with an exercise!




Drop-zone





Drop-zone

Robot





Drop-zone

RobotController





Drop-zone

RobotController


↑↰

P

↱

D

↑

↑




Drop-zone

RobotController

Goal: Max nr of paper balls in dropzone!


↑↰

P

↱

D

↑

↑




Discussion - groups of 4-6




What happened?




Daniel Brolund — @danielbrolund — [email protected] Brolund — @danielbrolund — [email protected]

An everyday empirical process...





Me





Me

Do I jump in...?





Schematic: Me

Do I jump in...?





Desired

Schematic: Me

Do I jump in...?





Desired

Desired

Schematic: Me

Do I jump in...?





Desired

Desired

Controller

Schematic: Me

Do I jump in...?





ControllerDesired

Desired

Controller

Schematic: Me

Do I jump in...?





ControllerDesired

Desired

Systeminput

Controller

Schematic: Me

Do I jump in...?





ControllerDesired

Systeminput

Desired

Systeminput

Controller

Schematic: Me

Do I jump in...?





ControllerDesired

Systeminput

Desired

Systeminput

Controller

System

Schematic: Me

Do I jump in...?





Controller SystemDesired

Systeminput

Desired

Systeminput

Controller

System

Schematic: Me

Do I jump in...?





Controller SystemDesired

Systeminput

Desired

Systeminput

ActualController

System

Schematic: Me

Do I jump in...?





Controller SystemActualDesired

Systeminput

Desired

Systeminput

ActualController

System

Schematic: Me

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

Schematic: Me

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

Time

Schematic: MeTemp

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

Time

Desired

Schematic: MeTemp

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

Actual

Time

Desired

Schematic: MeTemp

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

?Actual

Time

Desired

Schematic: MeTemp

Do I jump in...?





Actual==Desired ?


Systeminput

Desired

Systeminput

ActualController

System

Actual

Time

Desired

Schematic: MeTemp

Do I jump in...?

Robot




What is the control error?




Time

What is the control error?Temp




Time

Desired





Actual

Time

Desired





Actual

Time

Desired


"Error surface"




Actual

Time

Desired

Control Error = ∫|Desired-Actual|


"Error surface"




Actual

Time

Desired



"Error surface"

Time

Control error




Actual

Time

Desired



"Error surface"

Time

Control error∞




The "simplistic" solution


Systeminput






Systeminput Controller=(System)-1







⇒Desired = Actual







⇒Desired = Actual

Requires: - detailed knowledge of System, Desired and hence Actual - that such a Controller exists and can create such System input- that the System can handle System input







⇒Desired = Actual


Errorsε







⇒Desired = Actual


Errorsε

"Unlimited"energy

∞







⇒Desired = Actual


Errorsε

Change"Unlimited"

energy

∞







⇒Desired = Actual


Errorsε

Change"Unlimited"

energy

∞

Complexity







⇒Desired = Actual


Errorsε

Change"Unlimited"

energy

∞

Complexity

Won't work in reality




Drop-zone

Robot

Controller

Exercise 2




Drop-zone

Robot

Controller

Exercise 2

As before, but now only one step at a time!




Drop-zone

Robot

Controller

Exercise 2

↑





Drop-zone

Robot

Controller

Exercise 2

↑↰





Drop-zone

Robot

Controller

Exercise 2

↑↰↑





Drop-zone

Robot

Controller

Exercise 2

↑↰

P

↑





Drop-zone

Robot

Controller

Exercise 2

↑↰

P

↱

↑





Drop-zone

Robot

Controller

Exercise 2

↑↰

P

↱

↑

↑





Drop-zone

Robot

Controller

Exercise 2

↑↰

P

↱

D

↑

↑





What happened this time?





Adding feedback!

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Sensor

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Sensor

Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Sensor

SensorObserved result

Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Sensor

Error-


Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!

Feed-back or Closed-loop system

Sensor

Error-


Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!


Sensor

Error-


Time

Temp

Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!


Sensor

Error-


Time

Desired

Temp

Observed result

Systeminput

ActualController

Me

Desired

System




Schematic:


Systeminput


Adding feedback!


Sensor

Error-

SensorObserved result Actual

Time

Desired

Temp

Observed result

Systeminput

ActualController

Me

Desired

System




What is the control error now?





Actual

Desired

Temp






Time

Control error

Actual

Desired

Temp






Actual

Time

Control error

Actual

Desired

Temp






Actual

Time

Control error

bounded!!

Actual

Desired

Temp




In software: There are many feedback loops at play!




Live user feedback/release





Live user feedback/release Usability tests





Retrospective






Retrospective


Whiteboard discussions





Daily stand-up

Retrospective







ATDD

Daily stand-up

Retrospective







TDD

ATDD

Daily stand-up

Retrospective







TDD

ATDD

Daily stand-up

Retrospective


Pairing






TDD

ATDD

Daily stand-up

Retrospective


Compilation Pairing






SquigglesTDD

ATDD

Daily stand-up

Retrospective


Compilation Pairing






SquigglesTDD

ATDD

Daily stand-up

Retrospective


Compilation Pairing



...AND MANY MORE!




Exercise 3: Draw your own feedback loops

TDD 10s

Retros 1w

Release 1m




Drop-zone

RobotController

Exercise 4




Drop-zone

RobotController

Exercise 4

As before, but now now three steps at a

time!




Drop-zone

RobotController

Exercise 4

↑As before, but now now three steps at a

time!




Drop-zone

RobotController

Exercise 4

↑↰


time!




Drop-zone

RobotController

Exercise 4

↑↰↑


time!




Drop-zone

RobotController

Exercise 4

↑↰

P

↑


time!




Drop-zone

RobotController

Exercise 4

↑↰

P

↱

↑


time!




Drop-zone

RobotController

Exercise 4

↑↰

P

↱

↑

↑


time!




Drop-zone

RobotController

Exercise 4

↑↰

P

↱

D

↑

↑


time!




What happened this time?





The impact of delay

Systeminput

ActualController

System

Sensor

Me

Desired




The impact of delay

Systeminput

ActualController

System

Sensor

Error

-

Schematic:


Systeminput


-

Me

Desired




The impact of delay

Systeminput

ActualController

System

Sensor

Delay

Error

-

Schematic:


Systeminput


-

Me

Desired




The impact of delay

Systeminput

ActualController

System

Sensor

Delay

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Time

Temp

Delay

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Time

Desired

Temp

Delay

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Time

Desired

Temp

Delay

Tap temp

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Time

Desired

Temp

Delay

Tap temp

Tap tempError

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Time

Desired

Temp

Delay

Tap temp

Tap temp

Tap temp

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




The impact of delay

Systeminput

ActualController

System

Sensor

Observed result

Time

Desired

Temp

Delay

Tap temp

Tap temp

Tap temp

Error

-

Schematic:


Systeminput


-

Me

Desired

Delay




Delay considerations




Observed result

Desired

Temp

Tap temp





Observed result

Desired

Temp

Tap temp


delay > half of required cycletime ⇒

Guaranteed instability!(in practice, instability comes earlier)




Observed result

Desired

Temp

Tap temp


delay > half of required cycletime ⇒

Guaranteed instability!(in practice, instability comes earlier)

It often takes about 5-10 times the delay to tune the system




More delay considerations





Error

- Controller SystemActualDesired

Systeminput

Sensor

Observed result

-





Error


Systeminput

Sensor

Observed result

Delay position in loop is irrelevant w.r.t. instability!

-





Error


Systeminput

Sensor

Observed result

DelayDelay position in loop is irrelevant w.r.t. instability!

-





Error


Systeminput

Sensor

Observed result


-

Delay





Error


Systeminput

Sensor

Observed result

Delay


-





Error


Systeminput

Sensor

Observed result

DelayDelay position in loop is irrelevant w.r.t. instability!

-




Feedback delay considerations




Feedback cycle-time sweet-spots are different due to

processing and delays








slower that desired change ⇒

Unstable system








Unstable system

faster than desired change⇒

Controller overloaded or too expensive








Unstable system

faster than desired change⇒

Controller overloaded or too expensive

You want to shorten inner

feedback loops before outer!




Observability and controllability




Error- Controller System

ActualDesired

Systeminput



-





ActualDesired

Systeminput


Uncontrollable


-





ActualDesired

Systeminput


Uncontrollable

Unobservable


-




The Sensor has to measure

a relevant state (observability) that the

Controller can influence (controllability).


ActualDesired

Systeminput


Uncontrollable

Unobservable


-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Flow

-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Flow Acidity

-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Mineral tracesFlow Acidity

-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Mineral traces

Radioactivity

Flow Acidity

-








ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code


ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results


ActualDesired

Systeminput


Uncontrollable

Unobservable


Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results


ActualDesired

Systeminput


Uncontrollable

Unobservable


ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results

Acceptance test results


ActualDesired

Systeminput


Uncontrollable

Unobservable


ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results


Nr of checkins


ActualDesired

Systeminput


Uncontrollable

Unobservable


ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results


Nr of checkins Request statistics


ActualDesired

Systeminput


Uncontrollable

Unobservable


ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results




ActualDesired

Systeminput


Uncontrollable

Unobservable


User satisfaction

ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW







Lines of code

Unit test results




ActualDesired

Systeminput


Uncontrollable

Unobservable


User satisfactionUsability

ROI

Water temperature

Mineral traces

Radioactivity

Flow Acidity

-

SW




Noise




Signal

Noise




+

NoiseSignal

Noise




+ =

Huh?NoiseSignal

Noise




+ =

Huh?NoiseSignal

Signals must be filtered from noise. ⇒ Delays

⇒ Lower communication bandwidth

Noise




+ =

Huh?NoiseSignal

Signals must be filtered from noise. ⇒ Delays

⇒ Lower communication bandwidth

Noise

In SW-development, noise can be - Irrelevant information - Disinformation




What was the delay in the robot exercises?







What could you observe?






What could you observe? What could you control?







What was the noise?







What was the noise?

What was the signal?







How did all that affect you?

What was the noise?

What was the signal?




Error- Controller SystemActualDesired

Systeminput


Is feed-forward waste?

-





Systeminput


Feed-forward using the Controller is application of a priori knowledge.

We always need some of it to avoid re-inventing wheels.


-





Systeminput




TDD


-





Systeminput




TDD

ATDD


-





Systeminput




TDD

ATDD Daily standups


-





Systeminput




TDD

ATDD

Iterations

Daily standups


-





Systeminput




TDD

ATDD

Iterations

Daily standupsContinuous integration


-





Systeminput




TDD

ATDD

Iterations


Retrospectives


-





Systeminput




TDD

ATDD

Iterations


Deployment environments

Retrospectives


-




• How can you break the empirical process? What part?

• Controller?

• System?

• Sensor?

• Desired?

Failure modes - discussion in groups


Systeminput


-




• What does the following do to your feedback loops?

• Trust?

• Distrust?

• Lies?

• Care?

• What is noise according to you?

• What other "soft" issues will affect the system? How?

"Softer" issues - discussion in groups




http://www.azarask.in/blog/post/the-wrong-problem/






• Introduce feedback!

• Tune and prune the Sensors.

• Shorten inner feedback loops before outer.

• Reduce delays.

• Reduce noise.

Some of my best advice...



Thanks!

Daniel Brolund @danielbrolund [email protected]





the empirical process at agile india 2012

Business

everyday empirical process

medaniel brolund

medesired daniel brolund

discussion groups

max nr of paper balls

core of agile everythingdaniel