Practical Event Sourcing with Scala
Practical Event Sourcing with Scala
A comprehensive example based on Scala, Play and Akka Streams
About the Book
This book takes a very practical and rather unusual approach towards the event sourcing architecture. Instead of diving into the DDD terminology, which is usually popular in the Enterprise, we will use this pattern to implement a typical Web application.
You don't need to be a Scala guru to understand code samples, but some familiarity with the syntax is required. If you're completely new to Scala, I highly recommend you go through the free sample of my other book - Modern Web Development with Scala. The PDF sample could be read in an hour, but it covers most widely used syntax constructs.
Which versions are used
The main examples use Scala 2.13 and Play 2.8. When additional libraries are needed, their latest versions are used.
My special thanks go to Tim Ruhland for his enormous help in eliminating typos and errors. The cover illustration was designed by Freepik
Chapter 1. The initial project
- Preparing the environment
- Initializing the project
- The backend part
- The frontend part
Chapter 2. Handling simple events
- Event sourcing basics
- Preparing the event store
- Working with log records
- The read service
- Akka Streams in 5 minutes
- Updating the state with Akka Streams
- Producing events
- Implementing the controller
- Learning React in 5 minutes
- Managing tags with React
Chapter 3. Data processing pipeline
- Introducing Kafka
- Using Kafka from Scala
- Server-sent events
- Managing state with Redux
- Implementing Kafka consumers
Chapter 4. Validating and querying data
- Dealing with questions
- Linking questions to users
- Implementing server-side validation
- Introducing Neo4J
- The Cypher query language
- Executing Neo4J statements
- Rewriting the read service
- Integrating user-related events
- Initializing the state
Chapter 5. Frontend routing
- Adding the question controller
- Designing the views
- Nested views
- The Ask question view
- Showing validation errors
- The question list view
- Confirmation service
- Dealing with question threads
- The question details view
- Routing it all together
Chapter 6. Answers and upvotes
- Answers and upvotes
- Validating new event types
- Adjusting the read state
- Answers on the frontend
Chapter 7. Time travelling
- Rewinding in chunks
- Time travel dashboard
- Using Websockets
- Closing remarks
- Appendix A. Source code
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