1. Introduction of metadata: represents metadata in the form of comments, replacing the extensive configuration file in the past
2. The definition of various Enterprise Beans only needs to define some Pojo and Poji to match metadata to complete
3. The callback mechanism is also a notes used in conventional methods, instead of the original EJBCREATE.
4. Introduction of AOP Concept: Allows intercepting methods in class definitions and other classes
5. Dependent Injection: Allows objects depending on the property injection by adding a specific annotation
