You will learn how to use Contexts and Dependency Injection (CDI) to manage scopes and inject dependencies in a simple inventory management application.

The application that you will be working with is an inventory service, which stores the information about various JVMs that run on different systems. Whenever a request is made to the inventory service to retrieve the JVM system properties of a particular host, the inventory service communicates with the system service on that host to get these system properties. The system properties are then stored and returned.

Contexts and Dependency Injection (CDI) defines a rich set of complementary services that improve the application structure. The most fundamental services that are provided by CDI are contexts that bind the lifecycle of stateful components to well-defined contexts, and dependency injection that is the ability to inject components into an application in a typesafe way. With CDI, the container does all the daunting work of instantiating dependencies, and controlling exactly when and how these components are instantiated and destroyed.

You will use scopes to bind objects in this application to their well-defined contexts. CDI provides a variety of scopes for you to work with and while you will not use all of them in this guide, there is one for almost every scenario that you may encounter. Scopes are defined by using CDI annotations. You will also use dependency injection to inject one bean into another to make use of its functionalities. This enables you to inject the bean in its specified context without having to instantiate it yourself.

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