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>

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Table of Contents (12 chapters)
Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
Introduction to Reactive Programming
Introduction to Reactive Programming
Asynchronous programming
Summary
2
Programming Paradigm Shift
Programming Paradigm Shift
Programming paradigm
Functional programming
Declarative programming
Operator fusion
Summary
3
Reactive Streams
Reactive Streams
Discussing the Collection framework
Understanding backpressure
Summary
4
Reactive Types in RxJava
Reactive Types in RxJava
ReactiveX
Observer design pattern
The Iterator design pattern
RxJava
Hot or cold Observables
Creating Observable emitting sequential data
Transforming Rx non-compatible sequences into Observables
Creating Observables for unrestricted infinite length
Types of observables
Understanding the Disposable interface
Subject
Summary
5
Operators
Operators
Demystifying RxMarbles using an Observable
Transforming Observables using operators
Filtering Observable
Combining Observables
Conditional operators
The mathematical and aggregate operators
Summary
6
Building Responsiveness
Building Responsiveness
Concurrency
Scheduling
Latency
Summary
7
Building Resiliency
Building Resiliency
Resilience
Error handling in RxJava
Exceptions specific to RxJava
Error handler
Summary
8
Testing
Testing
Testing the need and role of a developer
The traditional way of testing an Observable
The modern approach for testing an Observable
Testing the Subscriber
The test() operator
Testing notifications
Mockito testing
Summary
9
Spring Reactive Web
Spring Reactive Web
An introduction to Spring Framework
The Spring architecture
Project Reactor
Spring web Reactive Programming
Server-side support
Client side
Server-Sent Events (SSE)
Summary
10
Implementing Resiliency Patterns Using Hystrix
Implementing Resiliency Patterns Using Hystrix
Hystrix- an introduction
Demonstrating HystrixObservableCommand
Handling fallback
Design patterns in resiliency
Queue-based load leveling pattern
Patterns used by Hystrix
Request collapsing or request batching
Request caching
Summary
11
Reactive Data Access
Reactive Data Access
Spring Data
Spring Data repositories
Spring Data and Reactive Programming
Spring Data Reactive and Redis
Kafka
Running the Kafka application
Summary

Server-Sent Events (SSE)

The servers enable pushing of the data to the Web pages over HTTP, or they may use server-push protocols. The subclass of the ResponseBodyEmitter class, SseEmitter, supports working with SSE. It's actually another variation of the HTTP Streaming technique in which the pushed events from the server are formatted according to the W3C Server-Sent Events specification.

These events can be pushed from the server to the clients, which now can very easily be done in Spring MVC, and requires returning a value of type SseEmitter. This sending of events plays a vital role in online gaming applications, applications for collaboration, and financial applications. Spring's WebSocket support includes SockJS style WebSocket, a higher-level messaging pattern for interacting with clients.

Let's update EmployeeController to add one more method that will now...

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