Event Sourcing & Event Modeling - Getting Started!

Name: Event Sourcing & Event Modeling - Getting Started!
Rating: 4.5 (17 reviews)

Build a strong foundation around event sourcing and event modeling to design, model, and implement robust systems!

Created byDomenic Cassisi

Last updated 6/2026

English

English [Auto],

What you'll learn

Learn and understand the essence of Event Sourcing
Model information systems using Event Modeling
Learn how to implement event-sourced systems
Apply learnings in practice through hands-on excercises
Learn and understand the latest innovations like DCB

Course content

11 sections • 70 lectures • 5h 59m total length

Welcome1:31
Course Overview2:05
Explore concepts and terminology for event modeling and event sourcing, then model and implement a review approval system across application and infrastructure layers with event stores, event streaming, and dcb.
About the Technology Stack Used in This Course0:53

Introduction1:23
Commands, Queries, and Events6:24
In this lecture, we will learn about commands, queries, and events, what they are, and how they differ from each other.
Commands, Queries, and Events
Command Query Separation (CQS)3:44
In this lecture, we will learn about the CQS design principle and how we can use it in software development.
CQS
Command Query Responsibility Segration (CQRS)5:23
This lecture introduces you to the CQRS pattern, how it compares to CQS, and how it can be applied.
CQRS
Event Sourcing12:10
Learn how event sourcing stores a sequence of immutable events, replays them to reconstruct state, and uses event streams, projections, and snapshots to support decision making and read models.
Event Sourcing -- Additional Reading1:30
Event Sourcing
Combining Event Sourcing with CQRS3:30
Combine event sourcing with cqrs to explore direct event store queries or separate projections that power a read model, enabling polyglot persistence, performance, and scalable, efficient queries.
Combining Event Sourcing with CQRS
Event Streaming3:11
Event Streaming
Event Modeling4:37
Explore event modeling, a timeline-driven method that maps commands, events, and views to tell a system's story through actions. Apply event sourcing-aligned blueprint to emphasize information flow across teams.
Event Modeling
Domain-Driven Design (DDD)4:33
Domain-Driven Design (DDD)
Event Sourcing with CQRS and DDD0:34
Vertical Slices5:45
Vertical Slices
Summary4:05
Glossary Reference1:16

Introduction2:15
Event-Sourced vs State-Stored Systems in Event Modeling2:19
This lecture is just a small disclaimer saying that you don't need event sourcing to do event modeling. The implementation of an event-modeled system is out of the scope of event modeling itself.
The Main Building Blocks4:51
Learn the main building blocks of event modeling—commands, events, and views—and how commands trigger behavior, events record immutable facts, and views expose information via read models.
Brainstorming and Exploring the Domain9:44
Wireframes & UI Mockups4:48
This lecture talks about the importance of UI mockups and wireframes and how they can be used in your event model.
State-Change Pattern2:05
Master the state change pattern, or command pattern, modeling how information enters the system and how behavior yields state changes. An add task command leads to a task edit event.
State View Pattern2:51
Automation Pattern5:09
Explore the automation pattern, which combines state view and state change to automate non-user steps in a workflow. See how a task archiver archives completed tasks using a to-do list.
Translation Pattern3:24
Explore the translation pattern to convert external events, such as GitHub issue opened, into local commands that produce task added events and update the read model.
The Patterns are Independent of Implementation0:52
Swimlanes3:39
Information Completeness Check5:16
Given When Thens (GWTs)7:15
Slices3:07
Summary3:10

Introduction1:07
Explore functional event sourcing and domain modeling to structure behavior in code, using commands, events, and state to implement decide, evolve, and react, and patterns like designer, view, and saga.
Kotlin - Programming Language Used in Examples0:16
Quick note on Kotlin, the programming language used, and call for alternative languages.
Three Fundamental Functions: Decide, Evolve, and React2:39
Explore how decide validates commands, evolve applies events to state, and react generates follow-up commands, enabling deterministic, testable domain workflows within event sourcing.
Decider Pattern14:27
View Pattern6:36
Saga Pattern8:12
Explore the saga pattern in functional event sourcing with a pure react function that converts action results into follow-up commands, demonstrated with EF model Kotlin examples and deciders.
Combining Deciders, Views, and Sagas0:47
Knowledge Check: Decider, View, and Saga
Summary1:20

Introduction1:16
Explore event modeling and event sourcing through a practical review approval system, from submitting reviews to moderator decisions and published and visible results, using a UI prototype to map behavior.
Exploring the UI Prototype and First Draft13:36
[Reminder] Event Modeling Flexibility0:41
Completing the Event Model6:49
Enhance the event model with swimlanes, explicit actors, and given-when-then tests to produce a clear blueprint of automations, moderators, customers, notifications, and bounded contexts.
Summary0:30

Introduction2:07
Explore dynamic consistency boundaries in event sourcing, examining aggregates, commands and queries, decision models, append conditions, and the DCP specification to build a practical mental model.
The Limitations of Aggregates12:40
Explore the limitations of aggregates in domain driven design, highlighting how static boundaries affect consistency, cross-boundary invariants, and evolving requirements, and examine approaches to mitigate complexity.
The Relationship Between Commands and Queries15:14
Decision Models9:03
Append Conditions11:42
Apply append conditions to maintain consistency in event-sourced systems using optimistic locking. Fetch events by a query, compare the last known position, and append new events to prevent concurrency issues.
DCB Specification4:26
Summary4:44

Requirements

Basic understanding of software architecture, software engineering, and functional programming
Experience in any programming language will be beneficial for hands-on lectures (Kotlin will be used in second half of the course)
Open to learn new approaches

Description

This course will give you a solid understanding of event sourcing and event modeling, two powerful approaches for designing and implementing software close to the domain of your business.

Instead of storing only the current state of your data, event sourcing captures every change as an immutable sequence of events. Event modeling builds on this by providing a structured way to design, visualize, and reason about your entire system through these events without going into detail about how the system is implemented.

Throughout this course, you will:

Learn the fundamental concepts and terminology behind event sourcing and event modeling.
Explore how commands, events, queries, and more work together to coordinate business processes.
Learn how to implement event sourcing using functional patterns like deciders, views, sagas.
Discover dynamic consistency boundaries (DCB) — a fresh way of thinking about consistency in event-sourced systems.
Put everything into practice by modeling and implementing a simple review approval system step by step.

The focus of this course is on concepts and patterns, not on a specific tool or framework. Most examples are written in Kotlin/Java, but the ideas apply to any technology stack.

By the end, you’ll have the knowledge and confidence to apply event sourcing and event modeling in your own projects — and to participate in ongoing discussions about where these approaches are heading.

If you’re a software engineer, architect, or anyone interested in better ways to model complex systems, this course is for you.

Who this course is for:

Software Engineers
Software and Solutions Architects
IT Leads and Engineering Managers
Product Management

Event Sourcing & Event Modeling - Getting Started!

What you'll learn

Explore related topics

Course content

Introduction3 lectures • 4min

Concepts and Terminology14 lectures • 58min

Event Modeling - Getting Started15 lectures • 1hr 1min

Functional Event Sourcing and Domain Modeling8 lectures • 35min

The Application Layer9 lectures • 1hr

The Infrastructure Layer3 lectures • 10min

Modeling a Simple Review Approval System5 lectures • 23min

Implementing a Simple Review Approval System4 lectures • 45min

Rethinking Event Sourcing: Dynamic Consistency Boundaries (DCB)7 lectures • 1hr

Where to Go From Here1 lecture • 1min

Requirements

Description

Who this course is for: