Book Image

Developing Middleware in Java EE 8

Book Image

Developing Middleware in Java EE 8

Overview of this book

Middleware is the infrastructure in software based applications that enables businesses to solve problems, operate more efficiently, and make money. As the use of middleware extends beyond a single application, the importance of having it written by experts increases substantially. This book will help you become an expert in developing middleware for a variety of applications. The book starts off by exploring the latest Java EE 8 APIs with newer features and managing dependencies with CDI 2.0. You will learn to implement object-to-relational mapping using JPA 2.1 and validate data using bean validation. You will also work with different types of EJB to develop business logic, and with design RESTful APIs by utilizing different HTTP methods and activating JAX-RS features in enterprise applications. You will learn to secure your middleware with Java Security 1.0 and implement various authentication techniques, such as OAuth authentication. In the concluding chapters, you will use various test technologies, such as JUnit and Mockito, to test applications, and Docker to deploy your enterprise applications. By the end of the book, you will be proficient in developing robust, effective, and distributed middleware for your business.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Mapping entity relationships


Database relationships are one of the most important concepts in relational databases. From an object-oriented programming perspective, database relationships are seen as an association relationship. An object may reference an instance of another class, or a list of instances of this class, and this is called association, or the has-a relationship in OOP, which maps directly to the concept of relational databases.

JPA provides a complete framework for mapping and using database relationships using object-oriented approaches. The rule of thumb is very easy: when an entity class references an instance (or a list of instances) of another entity class, this should be mapped to a database relationship. Four types of relationship exist in JPA:

  • One-to-one
  • One-to-many
  • Many-to-many
  • Many-to-one

Before moving on, let's refresh our concepts about these relationships. From an object-oriented perspective, when an entity references another singular entity, this is a to-one relationship...