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@cyriux @tpierrain #MemePasMal
Coder sans peur du changement, avec la "même pas mal !" architecture hexagonale
Cyrille MARTRAIRE (@cyriux) Arolla !
Thomas PIERRAIN (@tpierrain) Société Générale
@cyriux @tpierrain #MemePasMal
CODER SANS PEUR DU CHANGEMENT, AVEC LA "MÊME PAS MAL !" ARCHITECTURE HEXAGONALE
Cyrille MARTRAIRE (@cyriux) Arolla !
Thomas PIERRAIN (@tpierrain) Société Générale
Architecte
Société Générale
Thomas Pierrain
6
7
Passionate developer
PARIS Since 1999
!
@cyriux
Cyrille Martraire
Paris Software Craftsmanship Community
http://www.meetup.com/paris-software-craftsmanship/
TDDBDDDDDLegacy
Architecte Technique
Central
Architecte Technique
Central
Your own Sweets Box Online!Use-cases
1. Choose your box and the sweets to put inside
2. Get a price 3. Order, & consult
past orders
Let’s start
As usual: Chose the DB &
Design the DB schema!
STOP !
Alistair Cockburn
Uncle Bob Martin
Hexagonal
100% Domain Inside
Thin layer of Use-cases
Ports/Adapters all around
Adapter
Dependencies always towards the inside!
X
Allowed way for dependencies
Dependencies always towards the inside!
Vers l’intérieur, qu’il
dit le monsieur !
Ports/Adapters?“REST” Port
“REST” Adapter
“EMS“ Adapter
“Tibco EMS”
Port
Hexagonal?
Users Vs. Providers
THEY NEED ME
I NEED THEM
API (Application Provider Interface)
SPI (Service Provider Interface)
Tests Vs. Production
Deliver value to PROD
Verify behavior in TESTTest Robots Fakes, Mocks
Clients Stores etc.
Scenario-Driven…
Given a sweets box of size XL And a selection of 500g of M&Ms And assuming the following prices | item | price | currency | | XL Box | 2.50 | EUR | | M&M (100g)| 5.00 | EUR | !
When I ask for a price Then the price is 27.50 EUR
Modeling the domain…
Sweets
CustomSweetsBox
SweetsBoxPricerAllOrders
Catalog Order
ShippingCostEstimator
Caramels
Nougat
Fudge
Modeling the domain…
Sweets
CustomSweetsBox
SweetsBoxPricerAllOrders
Catalog Order
ShippingCostEstimator
Caramels
Nougat
Fudge
Beware of
Modelism!
I need to call external services, but I don’t want to know about
them
DIP principle
X
DIP principle
Interface
Adapter
interface
interface
REPOSITORY
interface
Start with mocks
MOCK
Add an html web app…
“REST” Adapter
We can demo!
Quick Win 1
Focus on what really
matters
Implement the repository
Implement the repository
On the
cloudz!
Implement actual persistence
interface
Amazon
Adaptor
Même pas mal !(“that didn't hurt one bit“)
Quick Win 2
Choose the technology last
(when we know best)
47
MAX IGNORANCE
48
Who’s that architect who can’t decide the technologies early?
Ebay as additional retailer?
Ebay as additional retailer!
“REST” Adapter
Ebay Adapter
Même pas …
New shipping provider?
interface
FEDEX
Adaptor
New shipping provider?!
Again:
Même pas mal !!!
Quick Win 3
Embrace the changes
X
Allowed way for dependencies
Hexagonal architecture
Quick Win 4
Low couplingHigh cohesion
Before (legacy architecture)
After (Hexagonal Architecture)
Quick Win 5Our business code is not victim of IT fads
anymore!
61
Hexagonal Architecture
Use & Abuse!
Need other areas of behaviors?
• Business intelligence? • Supply Chain management • CRM? • …
Même pas ! ;-)
Hexagonal all the things
New Bounded Contexts? New Micro-services?
Main benefits !
1.Focus on what really matters (business value first!) ➔ have you ever tried DDD?
!
2.Choose the technology last (when we know best our concrete needs) !
3.Embrace the changes (“Même pas mal !” / “that didn't hurt one bit“)
Thanks!Cyrille MARTRAIRE @cyriux
Thomas PIERRAIN @tpierrain
@cyriux @tpierrain #MemePasMal
CODER SANS PEUR DU CHANGEMENT, AVEC LA "MÊME PAS MAL !" ARCHITECTURE HEXAGONALE
Cyrille MARTRAIRE (@cyriux) Arolla !
Thomas PIERRAIN (@tpierrain) Société Générale
70
FUZZY
FUZZY
FUZZY
Pattern
Port Vs
Adapter?
Port = Existing Techno Adapter = Your code
You disagree?
Not that important.
Symmetries?
80
Not that important.
Inside vs.
Outside
Who’s talking about hexagonal?
Alistair Cockburn
84
”Uncle Bob” Martin
85
Steeve Freeman & Nat Pryce (GOOS)
86
Vaughn Vernon (IDDD)
87
Jeffrey Palermo (Onion Architecture)
88
h;p://pragprog.com/magazines/2009-‐12/going-‐naked
Depends on nothing
Pragmatic Programmers
Many notations!
Still, not well-known
+--------------+!| presentation |!|--------------|!| domain |!|--------------|!| persistence |!+--------------+
Layers?
+-----+-------------+----------+!| gui | file system | database |!|-----+-------------+----------+!| domain |!|------------------------------+
Infra the other way round!
Layering
http://matteo.vaccari.name/blog/archives/154
Inside vs.
Outside
Un Dedans et
Un Dehors
Un Dedans et
Un Dehors#des reperes pour nos enfants
For real
98
99
Ted Neward
We’re launching a startup, man.
Sentiment Analysis !
Automatically extract the sentiment of English sentences submitted on the web, using a given lexicon. Keep track of the
submitted sentences.
Your Turn !
5mn Small groups
Any technology / approach
Propose an architecture on paper !
Then we’ll debrief a selection of them
Sentiment Analysis !
Automatically extract the sentiment of English sentences submitted on the web, using a given lexicon. Keep track of the
submitted sentences.
105
How to enforce?
108http://books.sonatype.com/mvnref-book/reference/flex-dev-sect-creating-with-archetype.html
Maven multi-
module
110https://leanpub.com/livingdocumentation/
111
Living Diagrams
4 novel coupling metrics 1. Undesirable Dependency Count 2. Undesirable Distinct Dependency Count 3. Undesirable Dependency Max Repetition 4. Undesirable Distinct Assembly Count
!
Bad
Good
●Provoke conversations
Conformist vs.
Hexagonal
Conformist (accidental)
Hexagonal Architecture
Hexadecimal Architecture:
Need at least 16 layers in the code
Architecture = ?
Architecture !
”The key technology choices”BOF…
Architecture !
”What everybody should know”
Architecture !
”What’s hard to change”
Architecture !
”What’s irreversible”
Reversible decisions FTW!
Defer technology decisions
Change your
mind easily
50% TECH 50% COMM
50% TECH 50% COMM (10% MATHS)
Communication FTW!
AGRE
E
ON
MAXIM
S
”Le principe du nombril : on regarde vers l’intérieur”
Repository
Persistence Ignorance
!
!
•You can defer decisions about persistence (and UI) for a long ^me •Your domain must NOT care!
Un service, la facade coté mé^er d’un stockage !
Sans jamais parler de base de données.
Repository
h;p://www.andeka.co.cc/2011/07/postbox-‐251.html
Repository
h;p://www.andeka.co.cc/2011/07/postbox-‐251.html
Interface
DAO
Repository
In Legacy
Bubble Context
• Create a little bubble of innovation !
• Brand new model !
• As clean as we like • Highly tested • High hygiene standards
Bubble Context
• ACL to protect from the legacy code !
• Translates legacy objects & services into new, cleaner ones
Anti-corruption layer
Module (lib)
<<ValueObject<<ValueObject<<ValueObject>> <<ValueObject
<<ValueObject>>
<<Service>> <<SPI>>
<<Service>> <<API>>
<<En7ty>> <<Aggregate>>
Module ==
library
Accès aux services extérieurs
Module == library
Accès aux services extérieurs
Hexagonal Architecture
Scenario test data
Adapters
Bounded Contexts
Bounded Contexts
Il n’est pas possible de convenir du sens précis des mots u7lisés par un grand nombre de personnes.
!
Il faut accepter ce fait, et donc définir dans quel contexte un langage est clairement défini sans ambiguité.
Different
MY activity is not the same as YOUR event
Merci !
hFp://cathy313.centerblog.net/539-‐bisounours
Wrap-up
• Concepts & Messages – Subir -> Délibéré – Intérieur Vs Extérieur – Gérer ses dépendances – Langage interne / externe – DIP • Exemples • Kata
Content• When not to go Hexagonal? – Conformist – Facebook game – Too small (connector…) !
• Advanced aspects – The adapter pattern – Tech ports diversity – 1 Adapter – many interfaces – 1 interface – many adapters – Data push – Session management – Adapter as a module indeed
Content 2Domain model as a Pure Functions (100% no Entity inside) vs as Aggregates !
-- The Repository pattern Reuse slides
Hexagonal for a Bubble Context within a legacy !
Ports = surrounding legacy Adapters = repository / adapter !
Cloakroom / clandestine passenger patterns
Content 3How to enforce? !Discipline Maven multi modules, .Net projects Static analysis: JDepend rules, NDepend, Sonar plugins — Bounded Context Reuse slides !Conformist vs ACL isolation Same language or not? !Autonomous Components / Polyglot persistence !Influence of sync vs async / push vs pull on the inside of the hexagon !Examples?
Living Documentation Convention (YES)? Annotation on packages? !The Bounded Contexts / the Domain models vs the rest (ici un seul Bounded Context) !Domain model -> inside Everything else - that implements something from the domain model -> at the right - everything else that only calls -> at the left !
Apply DDD!
153
http://www.lexicalscope.com/blog/category/patterns/
http://matteo.vaccari.name/blog/archives/154
Problem: write a program that 1. Loads a set of employee records from a flat file 2. Sends a greetings email to all employees whose birthday is today !The flat file is a sequence of records, separated by newlines; this are the first few lines: last_name, first_name, date_of_birth, email !Doe, John, 1982/10/08, [email protected] !Ann, Mary, 1975/09/11, [email protected] !The greetings email contains the following text: Subject: Happy birthday! Happy birthday, dear John! with the first name of the employee substituted for “John” !3. REST service to query past greetings !HINT: today is a tech port! !!
+-----+-------------+----------+!| gui | file system | database |!|-----+-------------+----------+!| domain |!|------------------------------+
+--------------+!| presentation |!|--------------|!| domain |!|--------------|!| persistence |!+--------------+
Exercise
Postgres Sql + Gui (+ myBatis ?) Audit et log dans le domain + Metrics
