Context is everywhere. From our daily conversations to complex marketing campaigns, context is king. But in Software Development, are we suffering due to the lack of context? Sure we are. This presentation will give you a few highlights of why context is crucial to building software in the right way. The target audience of this presentation is engineers, managers, and product owners, looking for a DDD introduction.

1. Benefits of Context in
Software Development
By Frederico Cabral

2. Person A Person B
Where are you from?
I’m from Vancouver

3. Person A Person B
Where are you from?
I’m from Canada
? ?

4. Person A Person B
Where do you want to eat?
Sushi
Pizzaria
What do you want to eat?
Are you nuts?

6. Benefits of Context in
Software Development
By Frederico Cabral

7. Use case: Football Fans

8. Advertiseme
nt
Live Ticker
News
Products
Invoicing
Statistics
Football Fans Subdomains
Let’s dive
into it
Core
Support

11. Match
+ location (String)
+ when (DateTime)
+ nameTeamA (String)
+ nameTeamB (String)
+ currentScore (Score)
+ status (Status)
+ comments (List<Comment>)
+ score(…)
+ undo(…)
+ comment(…)
Score
+ teamA (Int)
+ teamB (Int)
+ asText(String)
Comment
+ by (String)
+ when (DateTime)
+ content (String)
Status (Enum)
+ Not started
+ Started
+ 2nd half Started
+ Finished
Football Live Ticker Model

12. Football & Tennis Live
Ticker

13. Match
+ location (String)
+ when (DateTime)
+ nameTeamA (String)
+ nameTeamB (String)
+ currentScore (Score)
+ status (Status)
+ isGrandSlan? (boolean)
+ comments (List<Comment>)
+ score(…)
+ undo(…)
+ comment(…)
Score
+ teamA (Int)
+ teamB (Int)
+ Sets (List<Set>)
+ asText()
Comment
+ by (String)
+ when (DateTime)
+ content (String)
Status (Enum)
+ Not started
+ Started
+ 2nd half Started
+ Suspended
+ Finished
Set
+ gamesWonPlayerA (Int)
+ gamesWonPlayerB (Int)
+ games (List<Game)
Point (Enum)
+ zero
+ fifteen
+ thirty
+ forty
+ deuce
+ advantage
+ game
Game
+ pointsPlayerA (Point)
+ pointsPlayerB (Point)
+ next(…)
Football & Tennis Live Ticker
Tennis specifics
(and very
simplified for
pedagogical
reasons)
Tennis Only
Football Only
Common
Huge Switch!
Football Score
<> Tennis
Score
Nullables!
Because they
are used for
different
scenarios

14. Football & Tennis &
Volleyball Live Ticker

15. Match
+ location (String)
+ when (DateTime)
+ nameTeamA (String)
+ nameTeamB (String)
+ currentScore (Score)
+ status (Status)
+ isGrandSlan? (boolean)
+ comments (List<Comment>)
+ scoreFootball(…)
+ scoreTennis(…)
+ scoreVolleyball(…)
+ comment(…)
Score
+ teamA (Int)
+ teamB (Int)
+ Sets (List<Set>)
+ asText()
Comment
+ by (String)
+ when (DateTime)
+ content (String)
Status (Enum)
+ Not started
+ Started
+ 2nd half Started
+ Suspended
+ Finished
Set
+ gamesWonPlayerA (Int)
+ gamesWonPlayerB (Int)
+ pointsTeamA (Int)
+ pointsTeamB (Int)
+ isTieBreak? (Boolean)
+ games (List<Game)
Point (Enum)
+ zero
+ fifteen
+ thirty
+ forty
+ deuce
+ advantage
+ game
Game
+ pointsPlayerA (Point)
+ pointsPlayerB (Point)
+ next(…)
Volley has sets,
but no “games"
Everything must
be nullable!
Volley use
“Teams" instead
of “Players"
Football & Tennis & Volleyball Live Ticker
MDDP
Monster Decomposition Design Pattern
Rules to mark as
“Finished" are
very unique

16. Bob
The creator of
Chris (new Joiner)
Must understand

17. Chris doesn’t know the code

18. Chris doesn’t know the code
Chris doesn’t know the context

19. • Code
• Code Design becomes simpler
• Better naming and intention revealing
• Improves code testability
• Productivity
• Decrease cognitive load
• Less side-effects when changing things
(Aka Bugs)
Benefits of Context in Software Development

20. Microservices

21. Match
+ location (String)
+ when (DateTime)
+ nameTeamA (String)
+ nameTeamB (String)
+ currentScore (Score)
+ status (Status)
+ isGrandSlan? (boolean)
+ comments (List<Comment>)
+ scoreFootball(…)
+ scoreTennis(…)
+ scoreVolleyball(…)
+ comment(…)
Score
+ teamA (Int)
+ teamB (Int)
+ Sets (List<Set>)
+ asText()
Comment
+ by (String)
+ when (DateTime)
+ content (String)
Status (Enum)
+ Not started
+ Started
+ 2nd half Started
+ Suspended
+ Finished
Set
+ gamesWonPlayerA (Int)
+ gamesWonPlayerB (Int)
+ pointsTeamA (Int)
+ pointsTeamB (Int)
+ isTieBreak? (Boolean)
+ games (List<Game)
Point (Enum)
+ zero
+ fifteen
+ thirty
+ forty
+ deuce
+ advantage
+ game
Game
+ pointsPlayerA (Point)
+ pointsPlayerB (Point)
+ next(…)
Football & Tennis & Volleyball Live Ticker
Score Team?
Status
Management
Team?
Comment Team?
Match Team?

22. Live Ticker
Comment Team
Score Team
Match Team
Comment
Service
Match
Service
Score
Service
Status Management
Team
Status
Service
Conway’s Law in Practice!

23. Match
Service
Comment
Service
Status
Service
Score
Service
Live Ticker
Volleyball has new
rules! We need to adjust
Changes
required
We fixed Volley, but we
introduced a bug for Tennis
We need to support
20 new sports
Changes
required
Changes
required
Match Service is down!
X
X
X

24. Volley
Service
Comment
Service
Tennis
Service
Football
Service
Another approach - Teams oriented by context
"Volleyball has new rules!
We need to adjust”
"We fixed Volley, but we
introduced a bug for Tennis”
"We need to support 20
new sports”
Change
s
required
X
Basketball
Service
"Volley Service is down!"
Other sports not impacted
X

26. Microservice is the problem

27. Context dissolved in many
services is the problem
Microservice is the problem

28. Teams oriented by context
Comment Team
Score Team
Volley Team
Match Team
Football Team
Comment
Service
Match
Service
Score
Service
Status Management
Team
Tennis Team
Status
Service
Changing the teams will
not immediately change
the software

29. the sooner the better,
otherwise…

30. More microservices will emerge…
Comment Team
Score Team
Match Team
Status Management
Team

31. • Architecture
• More insights for Distributed Architecture
• Loosely coupled and strongly cohesive
Microservices
• Team Topology
• Teams with more autonomy
• Less coordination effort
Benefits of Context in Software Development

32. Bounded Context = Language Boundary
Terms
Rules
Behaviour
Expected
Jargons
Facts and Events
Relationships

33. “In general, microservices should cleanly
align to bounded contexts. So, if our
service boundaries align to the bounded
contexts in our domain, and our
microservices represent those bounded
contexts, we are off to an excellent
start ensuring that our microservices are
loosely coupled and strongly cohesive”
Building Microservices: Designing Fine-
Grained Systems, page 33
Sam Newman
(@samnewman)

34. • Code
• Code Design becomes simpler
• Better naming and intention revealing
• Improves code testability
• Productivity
• Decrease cognitive load
• Less side-effects when changing things (Aka Bugs)
• Architecture
• Insights for Distributed Architecture
• Loosely coupled and strongly cohesive Microservices
• Team Topology
• Teams with more autonomy
• Less coordination effort
Benefits of Context in Software Development

35. How to identify our
Bounded Contexts?

36. Context can be fuzzy!

37. “if our models were music, they
would have the unmistakable sound
of completeness, purity,
power, and possibly even elegance
and beauty”
Implementing Domain-Driven Design
Vaughn Vernon
(@VaughnVernon)

38. • Linguistic boundaries
• Domain expertise
• Flow/Steps*
Some smells…

39. Event Storming
by Alberto Brandolini
https://www.eventstorming.com/

40. Bounded Context Canvas
by Nick Tune
https://medium.com/nick-tune-tech-strategy-blog

41. Domain Storytelling
by Stefan Hofer and Henning Schwenter
https://domainstorytelling.org

42. Conversation
"a talk, especially an informal one, between two or more people, in which
news and ideas are exchanged.”
(Cambridge Dictionary)

43. What’s next?

44. • Deep Dive your Subdomains and
Bounded Contexts
• Understand the relationship
types among your Bounded
Contexts
• Implement your new projects
using Context as the main driver
What’s next?

45. Domain-Driven Design:
Tackling Complexity in the Heart of Software
Eric J. Evans
Implementing Domain-Driven Design
Vaughn Vernon
Team Topologies: Organizing Business
and Technology Teams for Fast Flow
Matthew Skelton / Manuel Pais
Building Microservices:
Designing Fine-Grained Systems
Sam Newman