Question: I'm new in EJB & persistence at all, so excuse me please if I'll ask a stupid question.
I read a book about EJB and JPA, and faces phrase that I don't understand at all:

> 
> Intended to fully insulate developers from dealing directly with
>  persistence, it (EJB) introduced an interface-based approach, where
>  the concrete bean class was never directly used by client code.
>  Instead, a specialized bean compiler generated an implementation of
>  the bean interface to facilitate such things as persistence, security,
>  and transaction management, delegating the business logic to the
>  entity bean implementation.
> 
> 
> 

and 

> 
> The notion of container-managed entity beans was introduced, where
>  bean classes became abstract and the server was responsible for
>  generating a subclass to manage the persistent data.
> 
> 
> 

**What does it mean:** 

1. Specialized bean compiler generated an implementation of the bean interface
2. server was responsible for generating a subclass to manage the persistent data
Actually I can't grasp what mean generate implementation/subclass, does it mean in runtime?

Thank you in advance.

**EDITED:**

> 
> Finally, entity beans were modeled as remote objects that used RMI and
>  CORBA, introducing network overhead and restrictions that should never
>  have been added to a persistent object to begin with.
> 
> 
> 

**Does it also sink into nothingness?**

Answer: 
DirectX Math library design doesn't allow direct access to `XMMATRIX` and `XMVECTOR` members. It is likely because they store values in special [SIMD data types](https://msdn.microsoft.com/en-us/library/ayeb3ayc.aspx).

To read the components of an `XMVECTOR` you can use [`XMVectorGet*` acces functions](http://msdn.microsoft.com/en-us/library/windows/desktop/ee415582%28v=vs.85%29.aspx), for example:

```
XMVECTOR V;
float x = XMVectorGetX(V);
float w;
XMVectorGetWPtr(&w, V);

```

or [`XMStore*` functions](http://msdn.microsoft.com/en-us/library/windows/desktop/ee415635%28v=vs.85%29.aspx) to store it into a `XMFLOAT4`, which has scalar members with direct access:

```
XMVECTOR vPosition;
XMFLOAT4 fPosition;
XMStoreFloat4(&fPosition, vPosition);
float x = fPosition.x;

```

`XMMATRIX` you can store into a `XMFLOAT4X4`:

```
XMMATRIX mtxView;
XMFLOAT4X4 fView;
XMStoreFloat4x4(&fView, mtxView);
float fView_11 = fView._11;

```

There are also [Load functions](http://msdn.microsoft.com/en-us/library/windows/desktop/ee415589%28v=vs.85%29.aspx) to make the opposite: write to `XMVECTOR` and `XMMATRIX`.

For further information, refer to [DirectXMath Programming Reference](http://msdn.microsoft.com/en-us/library/windows/desktop/ee415574%28v=vs.85%29.aspx).

Happy coding!
I can't comment the answer, but i believe the correct code for XMMATRIX is:

```
XMMATRIX mtxView;
XMFLOAT4X4 fView;
XMStoreFloat4x4(&fView, mtxView);
float fView_11 = fView._11;

```

so that you can access the matrix member values using the newly created XMFLOAT4X4