Database Reference
In-Depth Information
System Migration Workbench (LSM Workbench). This primarily works by mapping the source
data structure onto the target data structures in SAP.
However, in the earlier systems, there were three different methods for achieving the same:
1. Batch Input
2. Direct Input
3. Fast Input
11.1.4 ABAP Objects
Before delving into the aspects of object orientation of SAP, we need to elaborate briefly on what
object orientation means. The object-oriented paradigm is based on a new way of looking at the
old dichotomy of data and computational procedures.
11.1.4.1 Object-Oriented Paradigm
A
paradigm
is the totality of techniques, tools, attributes, and patterns of thinking or exemplars
that constitute a world view. The 1960s were characterized by the
algorithmic view
, wherein the
primary concern was to design and implement correct and efficient algorithms, which were related
mostly to the performance issues of the numeric computations within the hardware constraints
of main memory and offline storage memory. Subsequently, attendant problems of programming
such as writing, debugging, and modifying led to the progressive crystallization of the
proce-
dural view
. In the procedural view, algorithms were packaged into subprograms or procedures and
handled independently of the programs using them. This gradually led further to the
structural
view
of the functional paradigm. In the functional paradigm, the focus is on the various functions
and subfunctions that a system has to perform and the manner in which those functions have to
be performed. The object-oriented view extends and couples this trend of abstractions not only to
operations (such as subprograms and procedures) but also to the data.
The principal building blocks of the object-oriented paradigm are four in number: object,
class, message, and method. They broadly correspond to the record, record type, procedure, and
procedure call in traditional language systems. A set of methods is sometimes referred as an
interface.
An
object
is a thing that exists and has identity (i.e., it occupies memory and is addressable).
An object consists of data that are tightly coupled with all the operations that can act against it.
The operations are referred to as
methods
, and the communication to the object triggering some
method is the
message
. A collection of such messages defines the public interface of the object, and
an object may be inspected or altered only through this predefined protocol of messages.
Because there is a considerable amount of commonality between the methods of several
objects, objects with the same internal structure and methods are grouped into a class called
the Class Defining Object (CDO) and are themselves called instances of this class. A class may
have multiple instance classes; however, each instance has only one CDO and keeps reference to
its CDO. Thus, a computation is performed by sending messages to an object, which inherits or
invokes a method of its CDO. This method in turn might invoke other objects by addressing to
them and so on. This chain might terminate when a primitive object is invoked that either changes
the instance variable or affects external entities such as the printer and hard disk. For instance,
gasoline and diesel cars can be seen as the instance (sub)classes of the four-wheeled vehicle object,
which itself is an instance (sub)class of the automobile class.