Book Image

Reactive Programming With Java 9

By : Tejaswini Mandar Jog
Book Image

Reactive Programming With Java 9

By: Tejaswini Mandar Jog

Overview of this book

<p>Reactive programming is an asynchronous programming model that helps you tackle the essential complexity that comes with writing such applications.</p> <p>Using Reactive programming to start building applications is not immediately intuitive to a developer who has been writing programs in the imperative paradigm. To tackle the essential complexity, Reactive programming uses declarative and functional paradigms to build programs. This book sets out to make the paradigm shift easy.</p> <p>This book begins by explaining what Reactive programming is, the Reactive manifesto, and the Reactive Streams specifi cation. It uses Java 9 to introduce the declarative and functional paradigm, which is necessary to write programs in the Reactive style. It explains Java 9’s Flow API, an adoption of the Reactive Streams specifi cation. From this point on, it focuses on RxJava 2.0, covering topics such as creating, transforming,fi ltering, combining, and testing Observables. It discusses how to use Java’s popular framework, Spring, to build event-driven, Reactive applications. You will also learn how to implement resiliency patterns using Hystrix. By the end, you will be fully equipped with the tools and techniques needed to implement robust, event-driven, Reactive applications.</p>
Table of Contents (12 chapters)
Free Chapter
1
Introduction to Reactive Programming

Request collapsing or request batching

In JDBC, we can combine more than one process as a part of the batch and then execute the batch at one time instead of executing individual queries one by one. Similar to JDBC, we can combine multiple requests together into a single HystrixCommand instance execution, as shown in the following figure:

Request-scoped and globally-scoped are the styles of request collapsing supported by Hystrix. The request-scoped collapser collects the batch per HystrixRequestContext and the globally-scoped collapse collects the batch for multiple HystrixRequestContext.

We can create the collapse implementation as an extension of HystrixCollapser. Each HystrixCollpaser accepts the following three generic types:

  • BatchReturnType: This is the type of batched command response. The collapser turns multiple commands into a batch of command. Here, we will specify...