The microBean JPA CDI Extension brings JPA to CDI.
If you are programming in an environment that already has JPA, such as a Java EE application server, then this extension is not for you.
If you are writing a Java SE program using CDI, then this extension may very well be for you.
In terms of end-user-observable effects, this extension allows you to do the following:
public class MyCDIBean {
@PersistenceContext(unitName = "dev")
private EntityManager em;
}
That is, you can inject an EntityManager as though your CDI-based
standalone Java SE program were in fact a Java EE application server
(at least with respect to JPA).
This extension jumps through a few hoops to ensure that everything is done as properly as possible.
Specifically, any DataSources behind the scenes are sourced from CDI
itself as just regular CDI beans. Additionally, if your CDI
implementation has transactional support, this extension will leverage
it. Yes, that means your persistence.xml can specify transactional
data sources.
This extension is often used in conjunction with the microBean JPA Weld SE Extension, the microBean Narayana JTA CDI Extension project and its Weld variant, and the microBean DataSource CDI HikariCP Extension.