Flavius Ștef: Big Rewrites Without Big Risks at I T.A.K.E. Unconference

1. Big rewrites without big risks
Flavius Ștef
https://flic.kr/p/9iuMzn

2. About meI train and coach
people in agile, lean
and leadership

3. Iterative and
incremental
Images: http://www.yoomee.com/about-agile

4. Why?
time
risk
time
risk
validate
validate validate validate validate

5. New skill: story splitting
●
Create-Read-Update-Delete
●
Workflow steps
●
Less usability first
●
etc.

6. x
x x
x
x
x x
x x x
Splitting
features
is easy

7. THE PROBLEM OFTHE PROBLEM OF
INCREMENTAL REFACTORINGINCREMENTAL REFACTORING

8. Sometimes we need a new architecture
●
Go faster
●
Reduce number of bugs
●
Improve an NFR
●
Respond to client demands
●
Respond to market (ex: cloud, mobile, web)

9. IncrementalIncremental
ArchitectureArchitecture
Refactoring?Refactoring?

10. Agile doesn't apply here!!!

11. But the questions remain
How do we know
the app still works?
How do we know
how much is done?
How do we know
when we'll finish?

12. STRATEGIESSTRATEGIES

13. Sorry, still
no silver bullet
Get creative!Get creative!

14. 1. Fake it till
you make it

15. Product 1
Desktop (C#)
Windows
Product 2 ~ Product 1
Desktop (C#)
Windows
Product 3
Desktop (C#)
Windows
Front-end platform
Java, JS
Awesome
NextGen Product
Linux-based
Web UI (Java, JS)

16. GUI
(C#)
Middleware
(C#)
RPC Hardware
Manager
(C++)
Packet
Generators
RPC
Old Product
WIN CLIENT TRAFFIC GENERATOR

17. GUI
(C#)
Middleware
(C#)
RPC Hardware
Manager
(C++)
Packet
Generators
RPC
Step 1. Research (1 Sprint)
TRAFFIC GENERATOR
GUI
(C#)
Middleware
(C#)
RPC Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATOR
GUI
(C#)
Middleware
(C#)
RPC Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATOR
WIN CLIENT
WIN CLIENT
WIN CLIENT

18. Step 2. Make MW run on Linux (2 Sprints)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI

19. Step 3. Link web UI with middleware (1 week)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI Send basic message between the two.

20. Step 3. Link web UI with middleware (1 week)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI
C# bindings
exist
PROBLEM:
Java bindings
don't exist
RPC
expected

21. Step 4. Walking skeleton (2 days)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI
Old MW
(C#)
Configure
different
scenarios Dump to disk
Hack: load dump
Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATOR
x
Start
Conf. #: 3
Google Chrome
OK!

22. Step 4. Walking skeleton (2 days)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI
RPC
Old MW
(C#)
Configure
different
scenarios Dump to disk
Hack: load dump
Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATOR
x
Start
Conf. #: 3
Google Chrome

23. Step 5. Read+write configuration (3 weeks)
Middleware
(C#)
LINUX CLIENT
Mono
Web
UI
RPC
Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATOR
RPC endpoint in C# existed in old product.
New product built Java RPC incrementally.
Read: How many NICs in the configuration?
Read: What are their Ips?
Write: Set IP of NIC #4
Write: Add a machine to configuration
Read: Another statistic
...
B
A
C
K
L
O
G

24. Timeline
Research
Make it run on Linux
Walking
Skeleton
Stories for demo version10d
20d
7d
15d
About 1 month

25. 2. I just don't love
you anymorehttps://flic.kr/p/rrHjG

26. Same product, different team
Middleware
(C#)
Mono
Web
UI
RPC
Hardware
Manager
(C++)
Packet
Generators
RPC
TRAFFIC GENERATORLINUX CLIENT

27. Step 1. Analyze dependencies & possible
replacements (2 Weeks)
Hardware
Manager
(C++)
MFC WinAPI
STL Boost
Find substitutes

28. Step 2. Proof of concept (2 Months)
Hardware
Manager
(C++)
MFC WinAPI
Hack alternatives for:
- (De)Serialization (MFC)
- IPC (WinAPI)
- …
STL Boost
CString → CMyString
CArray → CMyArray

29. Step 2. Proof of concept (2 Months)
“Hacked”
Hardware
Manager
STL Boost
Packet
Generators
#ifdef __vm
Implemented ~1% of use cases
- Select only one HW card
- Comment out other code

30. Step 3. Unit testing (2 Weeks)
CString sut = “foo”; CMyString sut = “foo”;
StringTestvalidate
against
validate
against

31. Step 4. Performance testing (2 Weeks)
CFile sut; CMyFile sut;
StringPerformanceTest
validate
against
validate
against
for (i=0; i<20000; i++)
CFile (MFC) 20x faster
than CMyFile (Boost)

32. Step 5. Incrementally remove Win dependency
2m 2m 1m
Remove MFC Remove WinAPI Final
testing
Windows Linux

33. Process
TRUNK
DEV
...1w
Runtests
Runtests
3d
Code
Freeze
Practices:
●
Software buildable and running at all times
●
Pull weekly from trunk
●
Run regression (10.000+ tests) every 3 days
●
Continuous integration (team level)

34. 3. One bite
at a time
https://flic.kr/p/CaNo1

35. Rewrite #1
4m 7m
Rewrite #2 Beta
Launch
An interface rewrite
2m
Abort!

36. Rally:
circa
2008

37. Rally:
circa
2009

38. What about
the stories
page?

39. Oh, there
were
changes...

40. 4. Rewrite the
story book

41. Three Amigos
Dev QA BA
Feature: ________
Scenario:________
Given ________
When ________
Then _________
Scenarios

42. PROCESSPROCESS

43. Set goal
Analyze
architecture
Create
backlog
Talk to QA
Pick
refactoring
RefactorTest
Update
backlog
Stop
Done?
YES
Integrate
NO
Add tests
if needed

44. Analyze
architecture
Create
backlog
Talk to QA
Pick
refactoring
RefactorTest
Update
backlog
Stop
Done?
YES
Integrate
NO
Add tests
if needed
Business
“Switch database vendors”
“Implement new features faster”
Or Technical
“Support 3000 concurrent connections”
“Centralize security controls”
Set goal

45. Set goal
Create
backlog
Talk to QA
Pick
refactoring
RefactorTest
Update
backlog
Stop
Done?
YES
Integrate
NO
Add tests
if needed
SWOT Analysis
(Strengths, Weaknesses,
Opportunities, Threats)
- What do we keep?
- What do we drop?
- What do we improve?
Analyze
architecture

46. Analyze
architecture
Set goal Talk to QA
Pick
refactoring
RefactorTest
Update
backlog
Stop
Done?
YES
Integrate
NO
Add tests
if needed
Architecture Epics
“Remove MFC”
“Move DB code from JSPs”
Create
backlog

47. Create
backlog
Analyze
architecture
Set goal
Pick
refactoring
RefactorTest
Update
backlog
Stop
Done?
YES
Integrate
NO
Add tests
if needed
What is the testing strategy?
Automation vs. exploratory
How often
Make sure testers are available
Talk to QA

48. Stop
YES
Talk to QA
Create
backlog
Analyze
architecture
Set goal
Pick
refactoring
RefactorTest
Update
backlog
Done?
Integrate
NO
Add tests
if needed
Mikado Method

49. Goal
Prerequisite Prerequisite
Prerequisite Prerequisite Prerequisite
The Mikado Method

50. Mikado Method
Move service
from Windows
to Linux
Fix Win API
compiler errs
Fix MFC
compiler errs
Fix CString
compiler errs
Write
CMyString
Replace CString
invocations

51. If you need some guidance selecting the
refactoring
http://www.sigs.de/download/oop_08/Stal%20Mi3-4.pdf+ Michael Stal: Architecture Refactoring Catalog

52. Michael Stal: source of architecture refactorings
●
Rename Entities
●
Remove Duplicates
●
Introduce Abstraction
Hierarchies
●
Remove Unnecessary
Abstractions
●
Substitute Mediation with
Adaptation
●
Break Dependency Cycles
●
Inject Dependencies
●
Insert Transparency Layer
●
Reduce Dependencies with
Facades
●
Merge Subsystems
●
Split Subsystems
●
Enforce Strict Layering
●
Move Entities
●
Add Strategies
●
Enforce Symmetry
●
Extract Interface
●
Enforce Contract
●
Provide Extension
Interfaces
●
Substitute Inheritance with
Delegation
●
Provide Interoperability
Layers
●
Aspectify
●
Integrate DSLs
●
Add Uniform Supp. to
Runtime Aspects
●
Add Configuration Subsystem
●
Introduce the Open/Close
Principle
●
Optimize with Caching
●
Replace Singleton
●
Separate Synchronous and
Asynchronous Processing
●
Replace Remote Methods
with Messages
●
Add Object Manager
●
Change Unidirectional
Association to Bidirectional

53. CONCLUSIONCONCLUSION

54. It's hard, but it can be done
Chunk the problem down
Encapsulate, stub, simulate
Work incrementally
Run tests
Validate against the goal
SUMMARY

55. THANKS!
Flavius Ștef
Twitter: @flaviusstef
Slides: slideshare.net/fstef
www.mozaicworks.com/blog/