Process Automation with Domain-Driven Design @ Navigate 2021

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This is our automated process! Process starts! Make decision Check HUMAN REJECT! FRAUD_S ERVICE ANTI pattern

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After five sprints, it finally works! RAUD_S ERVICE Check GET invoice POST negative amount Process ends. REJECT! Yes No ANTI pattern

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You got it?

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Eric Evans, 2004

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2004 2006 2008 2018 2010 2012 2014 2016 ? DDD … is not a book! It only started as a book. 2020

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Applying DDD to Process Automation …

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Process Automation "Done Right"

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No content

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2) Strategic Design The three pillars of Domain-Driven Design 3) Modeling in Code 1) Collaborative Modeling 1) Collaborative Modeling

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"Ubiquitous" Language DDD emphasizes the importance of language for modeling executable software.

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Stop nitpicking about "labeling"! Process starts! Make decision Check HUMAN REJECT! FRAUD_S ERVICE ANTI pattern

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Healthily obsess with language! Process starts! Make decision Check HUMAN REJECT! FRAUD_S ERVICE DDD Paradigm Invoice dispute raised Determine dispute handling strategy Economic relevance? Low: automatic handling Higher: manual handling Check invoice dispute Approved Approved Rejected Determine fraud potential Partially approved Partially rejected Dispute approved? Determine dispute handling strategy Check invoice dispute Determine fraud potential

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Healthily obsess with language! DDD Paradigm

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Think. Together.

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"Handing over" diagrams. ANTI pattern Analyst Developer Tester

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In DDD modeling is collaborative DDD emphasizes the importance of developing a shared mental model. DDD Paradigm

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You need workshop methods which enable everybody in a meeting room to contribute

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Understand the bigger picture of your domain! EVENTSTORMiNG

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Events (and more) on a timeline Something business relevant happened! Invoice dispute raised Invoice dispute approved Invoice dispute rejected Time

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Useful for process automation projects? Invoice dispute raised Invoice dispute approved Invoice dispute rejected Invoice dispute checked Yes! Time

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EVENTSTORMiNG Understand the bigger picture of your domain!

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Easily explore specific domain scenarios! EVENTSTORMiNG

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Useful for process automation projects? Invoice dispute raised Invoice dispute approved Invoice dispute rejected Invoice Check Fraud Detection Service Design sophisticated collaboration models with your domain experts Yes!

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Easily explore specific domain scenarios!

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storystorming.com

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2) Strategic Design The three pillars of Domain-Driven Design 3) Modeling in Code 1) Collaborative Modeling 2) Strategic Design

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Violating responsibility boundaries ANTI pattern Customer Care Fraud Prevention Billing

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Central orchestration Customer Care Fraud Prevention Billing Invoice Dispute ANTI pattern

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Subdomains & Bounded Contexts DDD Paradigm Customer Care Invoice Dispute Fraud Prevention Fraud Detection Billing Invoicing Crediting API C/S C/S C/S Internal Customer- Supplier Relationship

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Invoice Dispute Process (in Customer Care)

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Fraud Detection Process (in Fraud Prevention)

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Crediting Process (in Billing)

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Universal enterprise-wide model Customer Care Fraud Prevention Billing ANTI pattern

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Defined language boundaries DDD Paradigm Customer Care Fraud Prevention Billing API

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DDD's "ubiquitous language" is NOT universal

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Bounded contexts for models DDD Paradigm Customer Care Fraud Prevention Billing API

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2) Strategic Design The three pillars of Domain-Driven Design 3) Modeling in Code 1) Collaborative Modeling 3) Modeling in Code

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Search! Close! Jump! Customer Care Fraud Prevention Billing ANTI pattern Process controls other services

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Process automation IMPLEMENTS non-atomic, asynchronous services

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Processes implement a service DDD Paradigm Customer Care Fraud Prevention Billing API

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Intention revealing interfaces DDD Paradigm Billing API

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Synchronous interfaces Billing Sync API Customer Care What looks like a simple, fast and atomic operation today, can tomorrow turn out to be … ANTI pattern

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A long-running, async business operation

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Asynchronous interfaces Billing Async API Customer Care Feed Async APIs will NOT break, if you later need more than just a simple, fast, atomic operation to implement

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Objects & code inside the process Do not mix domain objects or domain code into your process model • No type safety or code completion! • Editing code in vendor-specific modelers? Nah. • Difficult or even impossible to test :-( • Complex domain objects as JSON ... seriously? process + objects + code Crediting ANTI pattern

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Processes as aggregates Model the process flow in a visual form 1 DDD Paradigm Invoice Dispute Process Model the domain objects in code 2 Invoice Dispute Root Entity 3 Bind them 1:1 and transition them as an aggregate 1 1 ${root}

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Chaotic consistency boundaries ANTI pattern Update with an ACID transaction A B

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Defined consistency boundaries DDD Paradigm Update with an ACID transaction B A Aggregates Strong consistency Eventual consistency