The strategies behind ddd – AdeoDevSummit 2022

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www.lilobase.me The strategies behind DDD @lilobase #DevSummit sundayapp.com

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Let’s start a new project !

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Sprint Zero Java or C# ? Spring Boot or Quarkus ? Kafka or Redis ? Microservices or Monolith ? Kubernetes or Nomad ? Angular or React ?

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Look, at our spring boot application with Kafka deployed on a K8S Cluster They know nothing about the project’s business domain … Sprint Zero

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Java or C# ? Spring Boot or Quarkus ? Kafka or Redis ? Microservices or Monolith ? Kubernetes or Nomad ? Angular or React ? These issues address only the solution

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But not the problem What should we do ? …

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Spring Boot or Quarkus ? Kafka or Redis ? Microservices or Monolith ? Kubernetes or Nomad ? Angular or React ? And that's why we are seen as technical expert Java or C# ?

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solution problem What should we do ? How are we going to do it ? It is an important discussion to have But only after we've fi gured out   what to do

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DDD is all about Alignment What should we do ? How are we going to do it ?

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DDD is all about Alignment What should we do ? How are we going to do it ?

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« Give a child a hammer and everything they meets has to be pounded. » – Abraham Kaplan

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« We put the needs of the database before the needs of the users, which results in some pretty crappy experiences » – @WalterStephanie

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www.lilobase.me DDD is all about Understanding @lilobase

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Domains & Subdomains Business Domain discovery THE software

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Domain Mapping Business Domain Classi fi cation Authoring & Publishing Customer Care Printing & Supply Chain Retail Store You need to acknowledge the fact that you have several domains

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Domain Mapping Business Domain Classi fi cation Authoring & Publishing Customer Care Printing & Supply Chain Retail Store Only one VP should be angry at a time

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Domain Mapping Business Domain Classi fi cation Authoring & Publishing Customer Care Printing & Supply Chain Retail Store These are neither Bounded Contexts nor Microservices

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Domain Mapping Business Domain Classi fi cation Authoring & Publishing Customer Care Printing & Supply Chain Retail Store These are your domains

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Domain Mapping Business Domain Classi fi cation Authoring & Publishing Customer Care Printing & Supply Chain Online Retail Store Payment processor Catalogue Invoicing Your domains contain domains

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Supporting Subdomain Generic Subdomain Core (sub)Domain Key differentiator Domains & Subdomains Business Domain Classi fi cation Essential to the   organization’s success Required for the   organization’s success Critical to the   organization’s success

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Domain Mapping Business Domain Classi fi cation Authoring Plateform Publishing & Printing Inventory Management Payment Processor Catalogue Invoicing Shipping Order Processing Proofreading

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Domains & Subdomains Business Domain Classi fi cation Authoring Plateform Inventory Management Shipping Payment Processor Catalogue Invoicing Order Processing Publishing & Printing Proofreading

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Domains & Subdomains Business Domain Classi fi cation Authoring Plateform Inventory Management Payment Processor Catalogue Invoicing Each business context is speci fi c Shipping Order Processing Publishing & Printing Proofreading

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Authoring Plateform Domains’ Connexion Reveal Business Relationships Inventory Management Shipping Catalogue Invoicing Order Processing Payment Processor It can highlight signi fi cant   sub-domain Publishing & Printing Proofreading

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www.lilobase.me DDD is all about Context @lilobase

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From Problem to Solution Authoring Plateform Publishing & Printing Inventory Management Shipping Payment Processor Catalogue Invoicing Order Processing Proofreading

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From Problem to Solution Authoring Plateform Publishing & Printing Inventory Management Shipping Payment Processor Catalogue Invoicing Order Processing problem solution Payment processor Invoicing Order Processing Shipping Authoring Plateforme Inventory Management Catalogue Publishing Proofreading Proofreading Inventory E-commerce platform Authoring Publishing

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Domains & Subdomains Development Strategy Supporting Subdomain In-House development with   external support if possible Generic Subdomain Outsourcing is an option Core (sub)Domain In-House development   with Your best teams Key differentiator

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Domains & Subdomains Development Strategy Supporting Subdomain Customized Off The Shelf Software   is an option Generic Subdomain Try to fi nd Off The Shelf solution Cost saving opportunities Core (sub)Domain Custom-made software High Cost & Quality Key differentiator

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From Problem to Solution Payment processor Invoicing Order Processing Shipping Authoring Plateforme Inventory Management Catalogue Publishing Proofreading Inventory E-commerce platform Authoring Publishing Authoring Plateform Publishing & Printing Inventory Management Shipping Payment Processor Catalogue Invoicing Order Processing Proofreading

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From Problem to Solution Inventory E-commerce platform Authoring Authoring Plateforme Publishing Catalogue Publishing Proofreading Authoring Plateform Publishing & Printing Inventory Management Shipping Payment Processor Catalogue Invoicing Order Processing Proofreading

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From Problem to Solution Business Domain & Architecture alignment Inventory E-commerce platform Authoring Authoring Plateforme Publishing Catalogue Publishing Proofreading These are your bounded contexts

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Inventory E-commerce platform Authoring Publishing Align your teams with your bounded context « Team assignments are the fi rst draft of the architecture » – Michael Nygard

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P Authoring Publishing E-commerce Stripe ShipMonk Shopify Context Mapping Relationship Hierarchy OHS OHS ACL OHS C/S

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Authoring Publishing E-commerce Specific Architecture style You don’t need one architectural style Beware of the CRUD ES CQRS CRUD ? Stripe ShipMonk Shopify

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Stripe Still no microservices Bounded Context ≠ Deployment units ShipMonk Authoring Publishing E-commerce Shopify Deployment Unit

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Deployment Unit Stripe Still no microservices Bounded Context ≠ Deployment units ShipMonk Authoring Publishing E-commerce Shopify Deployment Unit

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Domains are not immutable Understanding is a never-ending process Stripe ShipMonk Authoring Publishing E-commerce Shopify Printing

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www.lilobase.me DDD is all about Boundaries @lilobase

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Semantic Boundaries Between BC meaning are different Authoring Publishing Book Chapter Chapter They are not the same book What happens if the author revises his book?

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Semantic Boundaries Between BC meaning are different Chapter This is why you must start by understand strategically your domain Author Book Reviews Release Catalogue

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Semantic Boundaries Between BC meaning are different Authoring Publishing Book Chapter Chapter Book Chapter Chapter Inside a Bounded Context,   Don’t   Repeat   Yourself Between Bounded Context,   Write   Everything   Twice

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Don’t cross them Between BC meaning are different Authoring Publishing Author Reviews Author Book Book Release Never create relationships between entities from two BC

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Don’t cross them Between BC meaning are different Authoring Publishing Book Book Release Author Author Reviews This is exactly the same

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Don’t cross them Between BC meaning are different Authoring Publishing Book Book Release Author Author Reviews API API

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Same for Events Between BC meaning are different Authoring Publishing This is exactly the same Event   Bus Book Book Release Author Author Reviews

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Same for Events Between BC meaning are different Authoring Publishing Event   Bus Book Book Release Author Author Reviews Translator Translator

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Transactional Boundaries Protect your integrity Authoring Book Chapter Chapter Chapter Statistics Inside your bounded Context   live   Entities They are grouped in Aggregates

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Transactional Boundaries Protect your integrity Book Chapter Chapter Chapter Statistics They are retrieved and persisted   as a whole Inside an aggregate, Entities   share the same lifecycle

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Transactional Boundaries Protect your integrity Book Chapter Chapter Chapter Statistics Who ensures the aggregate integrity All interactions are done through the Aggregate Root Write a new chapter

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Transactional Boundaries Protect your integrity Book Chapter Chapter Chapter Statistics Write a new chapter Chapter Inconsistency

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Transactional Boundaries Protect your integrity Book Chapter Chapter Chapter Statistics But don’t put to much in it Author What happens if we delete the book ? They must share the same lifecycle

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Transactional Boundaries Protect your integrity Book Chapter Chapter Chapter Statistics Author reference Author Id

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Designing Boundaries Protect your domain Printing Team We need printing margin Book Chapter Chapter Chapter Release We need the colorimetric pro fi le Printing margin Colorimetric pro fi le API Publishing Team

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Designing Boundaries Protect your domain API We need printing margin Book Chapter Chapter Chapter Release We need the colorimetric pro fi le Printing margin Colorimetric pro fi le Domain Leakage Publishing Team Printing Team

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Designing Boundaries Protect your domain Publishing Team Printing Team Publishing API We need printing margin Book We need the colorimetric pro fi le Printing margin Colorimetric pro fi le Printing API We discovered the need   for an ACL

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www.lilobase.me DDD is all about Behavior @lilobase

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CRUD don’t express behavior It blinds you from the business perspective UPDATE address Relocation Mistake correction

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CRUD don’t express behavior It blinds you from the business perspective Relocation Mistake correction

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Data oriented programming It obfuscates your code – Mathias Verraes $order->setStatus('paid'); $order->setPaidAmount(120); $order->setPaidCurrency('EUR'); $order->setCustomer($customer);

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Data oriented programming It obfuscates your code $money = new Money(120, new Currency(‘EUR')); $order->pay($customer, $money); – Mathias Verraes $customer->pay($order, $money);

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Data oriented programming It obfuscates your code – Mathias Verraes $customer->pay($order, $money); $order->setStatus('paid'); $order->setPaidAmount(120); $order->setPaidCurrency('EUR'); $order->setCustomer($customer);

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Task Based UI Your customer’s need isn’t to fi ll out forms

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Users don’t need to fill out forms

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Users don’t need to fill out forms

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www.lilobase.me DDD is all about Compassion @lilobase

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A A A Ubiquitous language Stakeholders & Team Alignement Dev Domain   Expert Dev

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A A A not « just » a glossary Ubiquitous language Stakeholders & Team Alignement Dev Domain   Expert Dev

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Ubiquitous language Each BC has its own Authoring Publishing A A

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Ubiquitous language Each BC has its own Authoring Publishing A A A A It is a common cause of miscommunication

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Pair Programing The best way to share a domain understanding Dev Domain   Expert

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User He has the last word regarding domain implementation

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User Prioritize development & formalize users’ feedback

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User Power of Life and Death over the project

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User Too often forgotten

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User Maybe you could spend a day per month working with them ?

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User They design the software speci fi cation

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Know your users They might not be who you think they are Dev Domain   Expert Product   Owner Customer User What he understood goes   into production

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www.lilobase.me DDD is for every Projects @lilobase

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“A loosely coupled software architecture and org structure to match” is a key predictor of: • Continuous Delivery Performance • Ability to scale organization and increase performance linearly This is what DDD is All About ! — Michael Plöd (@bitboss)