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

Explaining mail protocols


Before delving into how to send emails via the Java Mail API, let's first gain an awareness of the different web protocols related to mailing systems. The three popular protocols used are POP3, IMAP, and SMTP. Both POP3 and IMAP are used to retrieve emails from a mail server, while the SMTP protocol is used to send (deliver) messages.

POP3 and IMAP

POP3 is a protocol used to access an email from the server, download new emails to the client, then delete the emails from the server. In POP3, if you have checked your emails from one device then tried to access them again from another device, you will find that your emails are no longer available, as they were deleted upon accessing them from the first device.

IMAP is also another email access protocol. Unlike POP3, it does not delete original emails from the server, and therefore is suitable for allowing email access from different devices, as your emails are always there on the server. Accordingly, it's the most widely...