java - EJB: seems I don't understand the crucial point -

I am new to EJB & amp; All of the perseverance, so please forgive me if I ask a stupid question. I read a book about EJB and JPA and face the phrases which I do not understand at all:

The developers intend to fully maintain themselves in order to fully deal, this (EJB) has an interface-based approach, where solid bean class is never used by client code directly Security was instead, in order to provide a specific bean compiler the Bean interface implementation features such as bare persistence, security and transaction management, entrust the business logic entity bean implementation.

and

The concept of container-managed unit beans was introduced, where the bean classes became more and the server consistently created the subclass to manage the data. Was responsible for.

What it means:

1. The specific Bean compiler has prepared the implementation of the Bean Interface

2. The server was continually responsible for creating a sub-class for managing data. Actually, I am not able to understand what it means to implement / subclass, what does it mean in runtime?

   Edited:

   Finally, the unit removes the beans Was modeled as objects that used RMI and Corba, used to start network overhead

   Does it sink even in emptiness? local interface and a remote

   1) Interface: / Code> Interface (if you were writing Bean MyEJB , then they were sent to MyEJBLocal and MyEJBRemote was to be ; will execute both MyEJB ). With this, the compiler generates some derivative classes that execute the methods, such methods only connect to the iJB server to obtain the bean and execute its methods.

   I am not so sure about 2, because we have many display problems that we ended up applying JDBC logic in session beans (I know, I know) ...