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Scala Reactive Programming

You're reading from   Scala Reactive Programming Build scalable, functional reactive microservices with Akka, Play, and Lagom

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Product type Paperback
Published in Feb 2018
Publisher Packt
ISBN-13 9781787288645
Length 552 pages
Edition 1st Edition
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Author (1):
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Rambabu Posa Rambabu Posa
Author Profile Icon Rambabu Posa
Rambabu Posa
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Table of Contents (16) Chapters Close

Preface 1. Getting Started with Reactive and Functional Programming FREE CHAPTER 2. Functional Scala 3. Asynchronous Programming with Scala 4. Building Reactive Applications with Akka 5. Adding Reactiveness with RxScala 6. Extending Applications with Play 7. Working with Reactive Streams 8. Integrating Akka Streams to Play Application 9. Reactive Microservices with Lagom 10. Testing Reactive Microservices 11. Managing Microservices in ConductR 12. Reactive Design Patterns and Best Practices 13. Scala Plugin for IntelliJ IDEA 14. Installing Robomongo 15. Other Books You May Enjoy

The CQRS pattern

CQRS stands for Command Query Responsibility Segregation. CQRS is an architectural pattern created by Greg Young, based on Bertrand Meyer's Command and Query Separation principle.

Greg Young, the father of CQRS, coined this term. The CQRS pattern was inspired by the Command Query Separation (CQS) technique.

Wikipedia defines this CQS as follows:

It states that every method should either be a command that performs an action, or a query that returns data to the caller, but not both. In other words, asking a question should not change the answer. More formally, methods should return a value only if they are referentially transparent and hence possess no side effects.

We know that every system or application has two kinds of operation:

  • Write operation (CREATE, UPDATE, and DELETE)
  • Read operation (READ)

If we don't follow the CQRS pattern, I mean using old...

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