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

Handling requests

As we discussed earlier in this chapter, all requests in Vert.x are handled by the Router class. We covered the concept of routing in the previous chapter, so now, let's just discuss the differences between the Ktor and Vert.x approaches to routing requests.

We'll declare two endpoints to delete cats from the database and update information about a particular cat. We'll use the delete and put verbs, respectively, for this:

router.delete("/cats/:id").handler { ctx ->
    // Code for deleting a cat
}
router.put("/cats/:id").handler { ctx ->
    // Code for updating a cat
}

Both endpoints receive a URL parameter. In Vert.x, we use a colon notation for this.

To be able to parse JSON requests and responses, Vert.x has a BodyHandler class. Now, let's declare it as well. This should come just after the instantiation of our router:

val router = Router.router(vertx)
router...