Presentation on Lean Architecture based on the Jim Coplien's book with the same name.

1. Lean Architecture
Dec.8, 2017
Kei Sugimoto (杉本 啓)
twitter: @sugimoto_kei
http://www.fusions.co.jp

2. ‘What-system-is’ and
‘what-system-does’
what-system-is
what-system-does
- user’s interest
- subject to change
- stable over time
- common across variants

3. What is a Lean Architecture?
• Is what-system-is.
• Should be designed upfront.
• Is not a ‘Big Upfront Design’.
• Does not have a lot of contents.
• Can be established in a relatively short time.

4. A Lean Architecture is a Form
Form
形態
Function
機能
Structure
構造
What end users and
customers cares.
What we implements.
Evolve over time
Stable over time

5. Traditional So-called
Architecture
Domain-dependent parts
(no contents)
Domain-neutral parts
(w/ contents)
function1 function2 function3
Based on the framework /application
dichotomy.

6. A Lean Architecture
Domain 1
Subsystem
(no content)
Domain 2
Subsystem
(no content)
Domain 3
Subsystem
(no content)
Domain 4
Subsystem
(no content)
How a system is partitioned regardless of
the framework /application dichotomy.
Module
1
Module
2
Module
3

7. 1st Design Step
Partitioning
• What-system-is versus what-system-does.
- Stable versus changing
• Conway’s law.
- Locality in dealing with changes.
- History, standards, convention, experience, common
sense.
• Partitioning is a business decision.
- Trade-off exists between team autonomy and
code duplication.

8. 2nd Design Step
Structuring into Modules
• Modules: not so administrative
as subsystems.
• Direct expression of the end-user mental
model.
• Follow domain knowledge (as timeless
compression of the end-user mental models).
• Apply a paradigm to separate commonalities
and variations.