Role Based Security, Interface, Abstract Classes

What is role based security?      The role based security is used to provide the security for the application based on the user roles registered with in the net work.Add windows form admin,user,guest. Migration from c# to vb.net:--       Importing the name space in first c# using name space hierarchy in vb.net imports name space hierarchy.c # declaring variables modifier data type variables.vb.net modifier variables as data type .c # modifiers are public,private,protected,internal,protected internal.vb.net note:all the above modifiers can be used with in the class and modules but they can not be used with in the methods and hence "DIM"modifier should be used.         c # class definition :class class name in the  brackets members(s).vb.net dim is same as the private but the different  is it can  de used every where.class definition class class name members(s) and end class.c # object creation:class name object name is equal to new class name(arg info);vb.net modifier object name as new class name (arg info);c # to access array elements:[],vb.net to access array elements ().    What is inter face?     it is a collection of members with out any definitions.syntax interface Interface name with in brackets members(s) with out any definition.   Note: the members presents with in the interface are bye default public.modifiers should  not be used while defining the interface members.in order to use interface members it is mandatory  that the interface should be implement with the support of a class.         The class which implements an interface should provide the definitions for all the interface members. else objects can not be defined for the class.a single class can provide an implementation for any no.of interfaces. syntax to define a class to implement an interface:class class name :interface name() with in brackets members(s).in this two child classes and parent classes one is father and another one is mother in this loan().child 2 two classes there.   Abstract  class:--   it is a collection of members with or with out any definition.the syntax abstract class class name with in brackets members(s) with or with out definition. Note:in order to use the members of a abstract class it is mandatory that the class has to be inherited and the derived class has to be provide the definition for the abstract    method.objects can not be behind for the abstract class.if the derived class does not provide the definition for the abstract method then the derived class should also be defined as abstract class.   java interview questions, Pega interview questions