Book Image

Java EE 8 Design Patterns and Best Practices

By : Rhuan Rocha, Joao Carlos Purificação
Book Image

Java EE 8 Design Patterns and Best Practices

By: Rhuan Rocha, Joao Carlos Purificação

Overview of this book

Patterns are essential design tools for Java developers. Java EE Design Patterns and Best Practices helps developers attain better code quality and progress to higher levels of architectural creativity by examining the purpose of each available pattern and demonstrating its implementation with various code examples. This book will take you through a number of patterns and their Java EE-specific implementations. In the beginning, you will learn the foundation for, and importance of, design patterns in Java EE, and then will move on to implement various patterns on the presentation tier, business tier, and integration tier. Further, you will explore the patterns involved in Aspect-Oriented Programming (AOP) and take a closer look at reactive patterns. Moving on, you will be introduced to modern architectural patterns involved in composing microservices and cloud-native applications. You will get acquainted with security patterns and operational patterns involved in scaling and monitoring, along with some patterns involved in deployment. By the end of the book, you will be able to efficiently address common problems faced when developing applications and will be comfortable working on scalable and maintainable projects of any size.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
5
Aspect-Oriented Programming and Design Patterns
Index

Explaining the concept of the service-activator pattern


Suppose a client needs to request a business service, which is a process that takes a long time. In this case, the client should not wait in a synchronous way until the end of the process. Instead, there must be a way to make an asynchronous service call that does not block the client or user. This service can then be activated at some point in the future. There may be several reasons for the delay of a process. For example, there may be a database query that consumes a lot of time, or an access to a legacy system that is beyond the control of the current application. The pattern of asynchronously performing the required task is known as the service activator.

So, the service activator pattern is always used when the client needs to call a service asynchronously. This means that the client makes the request and does not wait for the response.

We can imagine some alternative solutions to this problem. One method would be to send the request...