software engineering process i

Copyright © 2012-2014 by Mark J. Sebern

Software Engineering

Process ISE-2800-03


Ch. 3: Agile Principles

• Topic: why agile?• Ch. 3: Issues with plan-driven• But why would anyone use plan-

driven development?

(from course textbook)


The case for plan-driven development

• A380• >5000 ft2 floor space• up to 853 passengers• One plane: €3e8, or about $4e8.

• Inertial reference system: where plane is at, where it’s headed, at what speed• Gimbals, GPS, pressure/temp sensors

• 30 people for verification alone, millions of $• Also have flight control, communications,

etc.• Some planning may be helpful!


Agile Principles• Variability and uncertainty• Prediction and adaptation• Validated learning• Work in progress• Progress• Performance

Pair exercise

For your assigned topic,•What does it mean?•Does it make sense to you?•Prepare brief summary


Variability & Uncertainty• Embrace helpful variability to

create innovative solutions• Employ iterative and incremental

development• Leverage variability through

inspection, adaptation, and transparency

• Reduce all forms (ends, means) of uncertainty simultaneously


Prediction & Adaptation• Keep options open

• Accept that you can't get it right up front

• Favor an adaptive, exploratory approach

• Embrace change in an economically sensible way

• Balance predictive up-front work with adaptive just-in-time work


Validated Learning• Validate important assumptions

fast• Leverage multiple concurrent learning loops

• Organize workflow for fast feedback

Assume

Build

FeedbackInspect

Adapt


Work in Progress• Use economically sensible batch

sizes• Recognize inventory and manage

it for good flow• Focus on idle work, not idle

workers• Consider cost of delay


Progress

• Adapt to real-time information and replan

• Measure progress by validating working assets

• Focus on value-centric delivery


Performance

• Go fast but never hurry• Build in quality• Employ minimally sufficient

ceremony


What is the goal of this chapter?

• What is the challenge to the engineer who wants to start using Scrum?

• Variability, uncertainty: a new way to process the unknown

• Prediction, adaption: adaption > prediction• Validated learning: allow knowledge gained

to drive process• Work in progress: radical thoughts on how to

get work done• Progress: how to measure• Performance: focus on decreasing useless

work


Review

• The case for the waterfall/predictive models• Advantages of agile• Principles behind scrum• Next: sprints

software engineering process i

Documents

work doneprogress

agile principlestopic

replanmeasure progress

passengersone plane

fast feedbackcopyright

sebernreviewthe case

sebernperformancego

time workcopyright