Hamburg Wasser (Germany)

This chapter introduces the Spring Data project and three of its subprojects—Spring Data JDBC, Spring Data JPA, and Spring Data REST. It examines all the Spring Data features and explains how Spring Boot can help you use them in the two applications. Let’s get started.

In Chapter 7, we discussed how to use Hibernate with Spring when implementing data access logic with the ORM approach. We demonstrated how to configure Hibernates SessionFactory in Spring’s configuration and how to use the Session interface for various data access operations. However, that is just one way Hibernate can be used. Another way of adopting Hibernate in a Spring application is to use Hibernate as a persistence provider of the standard Java Persistence API (JPA), now renamed to Jakarta Persistence API.

Chapter explained how to build a Spring web application using classic, "manual"-style configuration and using Spring Boot with Thymeleaf. This chapter will take the application built in Chapter 14 and add a security layer that will declare which users are allowed to access various parts of the application. For example, only those users who logged into the application with a valid user ID can add a new singer or update existing singers. Other users, known as anonymous users, can only view singer information.

Transactions are one of the most critical parts of building a reliable enterprise application. The most common type of transaction is a database operation. In a typical database update operation, a database transaction begins, data is updated, and then the transaction is committed or rolled back, depending on the result of the database operation. However, in many cases, depending on the application requirements and the back-end resources that the application needs to interact with (such as an RDBMS, message-oriented middleware, an ERP system, and so on), transaction management can be much more complicated.

Faces Flows is a page-cohesion concept that entered the JEE world in 2013 with JEE version 7. Its main idea is that a couple of pages are said to belong to a "flow." Data associated with such flows and stored on the server can be confined to a flow scope, which means that all pages of a flow can access the same common flow scope data pool, and that the associated memory can be freed once the flow is exited. A flow variable scope thus lives between the request scope, where variables only survive a request, and the session scope, where data lives as long as a user session prevails.

Chapters and have introduced you to the Spring world, explaining why this framework is necessary and why dependency injection is so cool and useful. In essence, Spring was built to make dependency injection easy. This software design pattern implies that dependent components delegate the dependency resolution to an external service that will take care of injecting the dependencies. The dependent component is not allowed to call the injector service and has very little to say when it comes to the dependencies that will be injected. This is why the behavior is also known as the “Don’t call us, we’ll call you!” principle, and it is technically known as inversion of control (IoC). If you do a quick Google search, you will find a lot of conflicting opinions about dependency injection and inversion of control. You will find programming articles calling them programming techniques, programming principles, and design patterns. However, the best explanation comes from an article by Martin Fowler, which is recognized in the Java world as the highest authority when it comes to design patterns. If you do not have the time to read it, here is a summary: Inversion of control is a common characteristic of frameworks that facilitate injection of dependencies. And the basic idea of the dependency injection pattern is to have a separate object that injects dependencies with the required behavior, based on an interface contract.

In this chapter, you will learn:

Steinmetze oder Steinmetzen, lat.: Aciscularius bzw. Lapicida, Lapidarius mittelhochdeutsch: Steinmetze, althochdeutsch: steinmezzo; der zweite Bestandteil ist aus dem Galloroman. entlehnt; das vorausliegende vlat.