Class for IF_WD_CONTEXT_NODE

Hi Gurus,

I am new to WDA and OOPs . Some doubts

1 - Interface IF_WD_CONTEXT_NODE is implemented in which class.?

2 - What do you mean by attribute of an Interface (i.e WD_CONTEXT ) ?

TABLE_NODE = WD_CONTEXT->GET_CHILD_NODE( 'MY_TABLE_NODE' ).-- means what ?

3 - Why do we create objects of Interfaces and not classes that implement them ?

e.g data: TABLE_NODE type ref to IF_WD_CONTEXT_NODE.

4. Can i see the code for the CLASS that implements these INTERFACES ?

5. When and where are the objects for the classes created ?

(as in ABAP OOPs - CREATE OBJECT <varname> ).

Help me out.

Thanks in advance.