Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By : Alexey Soshin
Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By: Alexey Soshin

Overview of this book

This book shows you how easy it can be to implement traditional design patterns in the modern multi-paradigm Kotlin programming language, and takes you through the new patterns and paradigms that have emerged. This second edition is updated to cover the changes introduced from Kotlin 1.2 up to 1.5 and focuses more on the idiomatic usage of coroutines, which have become a stable language feature. You'll begin by learning about the practical aspects of smarter coding in Kotlin, as well as understanding basic Kotlin syntax and the impact of design patterns on your code. The book also provides an in-depth explanation of the classical design patterns, such as Creational, Structural, and Behavioral families, before moving on to functional programming. You'll go through reactive and concurrent patterns, and finally, get to grips with coroutines and structured concurrency to write performant, extensible, and maintainable code. By the end of this Kotlin book, you'll have explored the latest trends in architecture and design patterns for microservices. You’ll also understand the tradeoffs when choosing between different architectures and make informed decisions.
Table of Contents (17 chapters)
1
Section 1: Classical Patterns
6
Section 2: Reactive and Concurrent Patterns
11
Section 3: Practical Application of Design Patterns

Communicating with Event Bus

Event Bus is an implementation of the Observable design pattern, which we discussed in Chapter 4, Getting Familiar with Behavioral Patterns.

We've already mentioned that Vert.x is based on the concept of verticles, which are isolated actors. We've already seen the other types of actors in Chapter 6, Threads and Coroutines. Kotlin's coroutines library provides the actor() and producer() coroutine generators, which create a coroutine bound to a channel.

Similarly, all the verticles in the Vert.x framework are bound by Event Bus and can pass messages to one another using it. Now, let's extract the code from our ServerVerticle class into a new class, which we'll call CatVerticle.

Any verticle can send a message over Event Bus by choosing between the following methods:

  • request() will send a message to only one subscriber and wait for a response.
  • send() will send a message to only one subscriber, without waiting...