Design principles for an event driven architecture Commit Conf 2019 Luis García & Pablo Ruiz Madrid, November 2019 

Commercial Banking Retail Banking Why we are here 2 Luis García Castro @luiyo Pablo Ruiz Subira @prsubi 

Introduction 3 There is a perfect pairing between microservice-based architectures, Domain Driven Design (DDD) and event-driven architectures 

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Event Taxonomy 5 Meaning Driven Business Domain Raw Purpose Driven Technical Native Standardized Atomic raw domain Derived (*) business 

Taxonomy at microservice level 6 (*) each bus represents one specific topic in the Event Bus Domain API BB viewed from the outside Business Technical API Storage Bus Connector CORE Raw Domain Building Block internals Business Technical 

Standard language 7 API Call API Call Ubiquitous Language Ubiquitous Language Ubiquitous Language Standard Language 

Bounded Context Bounded Context Cohesion (strong) 8 Producer Consumer Schema Registry Send Schema Read Schema DB DB 

Reference Data 9 Building Block A Building Block B Master Reference Data Building Block C Datalake 

Coupling (loose) 10 Product A transaction received Fraud Engine transaction received Fraud Alert!! Communications transaction received Contact customer!! Channel Gateway Contact customer!! 

Correlation & Inference 11 Domain A Event A Domain B Domain C Event B Domain A Event A Domain B Domain C A & B A & NOT B 

Traceability & Lineage 12 Domain A Event Id: 1 TraceID: 1 Domain B Domain C Event Id: 2 TraceID: 1 Event Id: 3 TraceID: 1 Event Id: 4 TraceID: 1 Domain D Event Id: 5 TraceID: 5 

Aggregation / enrichment 13 Domain A Domain B Domain C Name: Peter Surname: Parker Job: Photographer Name: Peter Surname: Parker Alias: Spiderman Domain D Name: Peter Surname: Parker 

Orchestration 14 Orchestrator Generate Monthly Extract Product A Product B Document Mgm Product A movements Product B movements Statement request with Product A&B movements 

Choreography 15 Product A transaction received Category Service transaction received transaction categorized Customer Reporting transaction received transaction categorized 

Reconciliation 16 Domain A Domain B Domain C Domain D Reconciliation? Reconciliation? 

Privacy / Data Segregation 17 Producer Clear Message Clear Message Producer Consumer Name: Clark Surname Kent Income: 1234.00 Name: Clark Surname Kent Income: 1234.00 Other Consumer Name: **** Surname ***** Income: 1234.00 Consumer Other Consumer 

Technical/Business Monitoring 18 Domain A Domain B Domain C Alerting 

One Example 19 

Example 20 Person table Phone table Digital address table Gender type Phone type DA type PERSON 

Example 21 Change mobile phone number bus storage API Person Core raw CDC domain Risk Comm technical Contact hst gateway technical Auth Mobile phone number changed domain partner business x2 technical 

Example 22 Change mobile phone number bus storage API Person Core raw CDC domain Risk Comm technical Contact hst gateway technical Auth Mobile phone number changed domain partner business x2 1 Explicitly 1. Choreography 2. NOT reconciliation 3. NOT event enrichment 4. Correlation 5. Orchestration Everywhere: • Event taxonomy • Strong cohesion • Loose coupling • Lineage and traceability 2 3 4 technical 5 

How EDA impacts a microservice based architecture 23 Feature EDA impact Loosely coupled Location transparency Strong cohesion Organized around business capabilities Each service is independently deployable Highly maintainable – Easy to maintain Highly testable – Easy to test Each service is as simple as possible Data Management Transaction Management 

Thank you!! Questions? 24