The document discusses agile architecture and lean principles. It advocates applying systems thinking to understand how users and processes really work in order to improve them without relying solely on technology. The document also discusses techniques like domain-driven design, modeling approaches like data-context-interaction, and the importance of exploring architecture and design upfront through spikes and prototypes to develop the right system.

1. Agile architecture
The next silver bullet to solve all your problems
Magnus Mickelsson, Citerus AB
magnus.mickelsson@citerus.se
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2. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Upfront
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3. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Upfront
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4. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Agile methods
• Deliver working software
• Individuals/communication > processes and tools
• Close to the business
As a .. <role>
• User stories I want .. <function>
So that .. <purpose>
• Engineering practices
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5. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Engineering Practices
DONE
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6. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Cowboy-architecture
• Hack something that works, then ”refactoring”
• Structures and patterns emerge..
• .... sometimes.
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7. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Cowboy-architecture
• Hack something that works, then ”refactoring”
• Structures and patterns emerge..
• .... sometimes.
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8. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Where do we place ourselves on the scale?
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9. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Lean-principles
• Go out and see
• Optimize value flow
• Eliminate waste
• 5xWhy?
• Pull, not push
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10. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Lean-principles
• Defects
• Go out and see
• Waiting
• Optimize value flow
• Over-production
• Eliminate waste
• Transport
• 5xWhy?
• Complexity
• Pull, not push
• Unused creativity
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11. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Systems thinking
• How do things really work?
• How do our users work?
• What are the consequences of the current way?
• Improve the process (without IT)
• Pull IT into the improvement work
http://vimeo.com/19122939
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12. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Lean/Agile architecture work
• Working software
• Working with people > specifications
• Increase knowledge in the organisation
• Eliminate waste
• Systems thinking - optimise the whole
• Be ready to get ”pulled” in
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13. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
”Lean Architecture” - Coplien/Björnvig
• ”All together, from early on”
• Reduce need for things that slow down
• Think Lean, be Agile
• Some upfront-work => what the system is
• Use-cases good for what the system does
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14. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DDD - Domain-driven Design
• Cooperation with domain
experts yields invaluable
knowledge
• Let the domain control the
solution design, not technology
• Design that makes maintenance
and developer testing easier
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15. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DDD is not just application design
• Big Balls of Mud + Entropy -> Core Domain
• Context mapping
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16. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Whirlpool model exploration method
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17. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Example #1 - simple/isolated webapp
• Now, target, expectations
• How do things really work?
• What can be done without IT?
• Gather user stories (detail a few)
• Ubiqutous language (DDD)
• Explore architecture/design - sprint 0
• 1-2 spikes
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18. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Explore, think, test, measure, improve...
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19. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
... and maybe, just maybe ...
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20. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Example #2 - average to large system
• Systems thinking
• Use-cases or user stories?
• Context mapping
• Architecture (form) - what is the system?
• Map subsystems to teams
• Explore what the system does
• Focus on Lean, to be Agile
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21. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Model-View-Controller
Model
View Customer
Service
Controller Account
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22. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DCI - Data, Context, Interaction
Model/Data
View Customer
Controller Context Account
Role Role
Interaction
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23. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DCI - Data, Context, Interaction
Model/Data
View Customer
Controller Account Account
transfer
Source Target
account account
Interaction
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24. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DCI - Data, Context, Interaction
Model/Data
View Customer
Controller Account Account
transfer
Source Target
account account
Account Account
Interaction
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25. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
DCI - Data, Context, Interaction
Model/Data
View Customer
Controller Account Account
transfer
€
Source Target
account account
Account Account
Interaction
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26. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
What’s worth taking home?
• What can be done without IT? Systems thinking
• Use-cases or user stories?
• How much ”form” upfront depends
• Lean principles help us stay Agile
• DDD, Context mapping, DCI
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27. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Questions?
magnus.mickelsson@citerus.se
magnus.mickelsson@gmail.com
Twitter: magnusmickel
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28. Citerus - Magnus Mickelsson, 2011 - magnus.mickelsson@citerus.se - 0708-444183
Reading tips
• Lean architecture (Coplien/Björnvig)
• The Pragmatic Programmer (Hunt/Thomas)
• Domain Driven Design (Evans)
• Working effectively with legacy code (Feathers)
• Refactoring to patterns (Kerievsky)
• Lean Software Development (2*Poppendieck)
• Freedom from Command & Control ... (Seddon)
• Evolutionary architecture & Emergent Design (Ford)
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