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Reactive Architecture(6): CQRS & Event Sourcing

Learn CQRS, and Event Sourcing, and see how they can be applied when building Reactive Systems.




About This Course

Command Query Responsibility Segregation (CQRS), and Event Sourcing (ES), are powerful tools. They can make the difference between an application that evolves, and remains competitive, or one that stagnates and falls into obscurity. This course will discuss the reasons we use CQRS/ES, what benefits it provides us, but also what it will cost us to use. We will see how CQRS/ES can impact the scalability, consistency, and availability of our application. Most importantly we will learn about one of the key techniques that is used in building modern Reactive Microservices.

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Course Syllabus

  • What is CQRS/ES?
    • A brief introduction to CQRS/ES, and what situations it should be applied in.
  • Event Sourcing
    • An introduction to traditional, state-based persistence techniques, and where they break down.
    • A discussion of Event Sourcing, and how it can overcome the limitations of state-based persistence.
    • Details around how Event Sourced models can be evolved.
    • A short introduction to Command Sourcing, and how it contrasts with Event Sourcing.
  • CQRS
    • A discussion of the conflict that arises from having a unified model for reads and writes.
    • Details of how CQRS can be used to solve the model conflict.
  • Consistency, Availability, and Scalability with CQRS
    • How CQRS can be used to create fine grained microservices.
    • The impact of CQRS on the Consistency, Availability, and Scalability of the system.
    • A discussion of the costs of CQRS/ES, both real, and misunderstood.

General Information

  • This course is free.
  • It is self-paced.
  • It can be taken at any time.
  • The materials can be reviewed as many times as you want.
  • Quizzes and exams can only be completed once.

Grading scheme

  • The minimum passing mark for the course is 75%, where the review questions are worth 40%, the case study exercises are worth 30% and the final exam is worth 30% of the course mark.
  • You have 1 attempt to take the final exam with multiple attempts per question.

Course Length

  • Approximately 6 hours


Course Staff

Wade Waldron

Wade Waldron

Wade Waldron is the Director of Training at Lightbend. He is the primary author of the Lightbend Reactive Architecture training course.

Wade started his career as a developer in 2005 building games for the Playstation 2, Xbox, etc. In 2011 he joined Point2 Homes where he began working on an Akka based microservices platform to provide realtime updates to real estate websites. In 2014 Wade joined BoldRadius where he consulted with a variety of companies on how to use Akka, and related technologies. He also began teaching courses on Akka and Scala.

In 2016, Wade released a book "Applied Akka Patterns" along with his co-author Michael Nash

Today Wade works with Lightbend where he consults with clients and builds training materials. He focuses on helping people make a smooth transition from a monolithic application to Reactive microservices.