ABAP_to_the_Future

Creating and Using Shared Memory Objects 14.2
Integration (PI) proxies to achieve the sa me end. In this example, the data is
going to come from shared memory. It turns out that this will require two further
layers, both of which are known to the persistency layer: the broker class
and the root class.
왘 The broker class is a class that handles shared memory areas for the given set of
data. The persistency class uses this shared memory handling class to access the
innermost layer. The broker class is a generated class, and you don’t do any custom
coding inside it.
왘 Finally, the innermost layer is the so-called root class, and this is where you do
our own coding for where in the database you want to get the data from initially.
You also can add a whole bunch of whatever methods you see fit to use
in order to control what data gets storedand how it gets changed and accessed.
Broker Class: What’s in a Name?
They say that the Eskimos have 200 words for snow; in the same way, SAP often uses
multiple terms to mean the same thing. In the realm of shared memory, the terms “broker
class,” “area class,” and “handle” are used interchangeably. To avoid confusion, this
chapter sticks to “broker class”; it’s arguab le the best of the three phrases, because it
describes the task of the class in human terms—that is, to act as an intermediary, a broker,
between the calling program and the root class.
The user interface and controller layers were, of course, the focus of earlier chapters
in the book. In this section, we concentrate on the layers from the persistency
layer inward. First of all, you will create the root class, in which all the action
(your own code) happens. Then, you will learn about creating the broker class,
which serves as the interface between the custom code in the root class and the
persistency layer in any ABAP programs that want to take advantage of shared
memory. Finally, you’ll discover how to call the broker class from a persistency
layer class.
14.2.1 Creating the Root Class
This type of class does not want to change the world; it only has one job, which
is to store data and then let anyone in the system who is authorized to do so
access that data. Just as Spiderman can do whatever a spider can, this root class
can do whatever a normal class can, which makes it a lot cleverer than a database
table. It cannot swing from a web, but it can perform complicated authorization
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