Domain Driven Design and Event Sourcing with RIM

Domain Driven Design and Event Sourcing with RIM

Introduction RIMResistance is Futile, you Will be Assimilated! 1

DDD and Event Sourcing • Introduction – George de la Torre • Developer of custom clinical apps • For a long time • Discovered RIM a long time ago… – Oleg Sitalo (silent partner) • Developer of custom clinical apps • For a long time together • Believes in RIM, at occasions… 2

DDD and Event Sourcing • Agenda – Google will find heaps of stuff on this – Will focus on the RIM stuff – Great resources for DDD/ES • http: //msdn. microsoft. com/enus/library/jj 554200. aspx • Implementing Doman-Driven Design – Vaughn Vernon • Domain Driven Design (the Blue Book) – Eric Evans 3

DDD and Event Sourcing • Domain Driven Design – Object Oriented Model – Business needs & language captured – HL 7 v 3 RIM benefits • • • Design done! – the hardest part Standard – open & shared to all Deep insights into domain knowledge Integration of domains built in (No barriers!) Reuse logic across clinical domains 4

HL 7 V 3 RIM Domain Model Blueprint for all Aggregates 5

Vocabulary Supporting Domains External Services Bounded Contexts 6

Supporting Domains External Services Anti Corruption Layer Other systems or Big Ball of Mud… Business Process and Rules Engines Point: This layer keeps RIM pure! 7

DDD and Event Sourcing • Event Sourcing – Only the Aggregate (D-MIM) is persisted – The command is saved (Behavior) – Aggregates publishes the events – Command Query Responsibility Segregation (CQRS) • Command (Transaction) Model • Query Model 8

Patient Dashboard Example Use Case • Schedule a patient visit – Find Patient (Query Model) – View Calendar (Query Model) – Patient assigned time slot (Command) – Create. Appointment. Command(data) executes • Scheduling aggregate is created from data • The created aggregate is appended • Publishes event to update Query Model 9

Scheduling Aggregate Example 10

Scheduling Aggregate CMET (PAT) is the Root 11

Scheduling Aggregate • Considerations – Entity is usually the Root – No cloning, only class codes – Aggregates varies with the RIM set – Act may be the Root (Strategy) • • Reference others Aggregates (Observations) Act Mood partitioning PHI segregation requirement (Query model too) Performance 12

Scheduling Aggregate • Considerations continued… – Serialized, XML, JSON, etc… – Relational Database (SQL) – Cache based systems – File systems – No. SQL • Natural for event stores • Easier to query Aggregates if needed • Aggregates loaded for logic on command 13

Scheduling Aggregate Appended Create. Appointment. Command(data) Event Store ID Name Version 1 Schedule 1. 2 2 Schedule 1. 2 3 Schedule 1. 2 Data 14

Scheduling Aggregate Publishes Events Appointment. Created. Event(data) { Update. Database. View() } Query model MRN First Last DOB Phone Start End Note 15

Scheduling Aggregate Publishes Events Appointment. Created. Event() { Create. Admission. Message() } HL 7 2. x MSH|^~&|ADT 1|MCM|LABADT|MCM|198808181126|SECURITY|ADT^A 01|MSG 00001|P|2. 3 EVN|A 01|198808181123 PID|||PATID 1234^5^M 11||JONES^WILLIAM^A^III||19610615|M-||C|1200 N ELM STREET^^GREENSBORO^NC^27401 -1020|GL|(91 -9)379 -1212|(919)2713434||S||PATID 12345001^2^M 10|123456789|9 -87654^NC 16

Scheduling Aggregate Publishes Events Appointment. Created. Event() { Update. Data. Mart() }

Patient Dashboard Example Two Separate Models (CQRS) • Domain (Transaction) Model – Complex structure (RIM) – Aggregates are only created from RIM – Aggregates are appended (Write Only) • Query Model – Simplified model structure (SQL) – Multiple models created as needed – Model optimized for querying (Read Only) 18

Simple Component Design CQRS Web Dashboard Query Commands App Services Aggregate Services Events Publishes to View Model SQL 19