ABAP_to_the_Future

Top-Down Development 15.2
Summary
In this section, you’ve created a DDL objectin Eclipse, in which you wrote a much more
complicated SQL statement than would be possible in ABAP. When the DDL object
activated, an SE11 view was created on the ABAP system, and a CDS view was created
in the SAP HANA database.
Before the CDS view concept came along, you had to retrieve the data from the database
using a view and then do some manipulation of that data in your ABAP program.
Now, because the CDS view (which runs in the database) has taken over some of the
tasks that formerly you would have done in the ABAP program (which runs on an application
server), those tasks—or, more accurately, the code to do those tasks—has been
pushed down into the database.
15.2.2 Building and Calling ABAP Managed Database Procedures
In Section 15.3, you’ll see that, in the bottom-up development approach, the call
to a stored procedure is a bit like usin g a function module—that is, very procedural
(old-fashioned). With the top-do wn approach, you have instead an ABAP
Managed Database Procedure (AMDP), which is a method of a class and thus fully
object oriented.
As you know, when you create classes and methods of a cl ass, there are two
things you need to code: the definition and the implementation. The process for
an AMDP is exactly the same. First, you’ll look at how to define a class such that
one or more of its methods can be execut ed directly on the database by means
of an SAP HANA stored procedure. Then , you’ll learn how to code the implementation
of such a method using SQLScript, such that although the code is
written in the ABAP system it will actual ly execute inside the SAP HANA database
at runtime.
Defining the ABAP Method
If you have a class that has at least one method in which you would like to delegate
processing to the database, then th e only change you need to make to the
definition of that class is to include the interface IF_AMDP_MARKER_HDB, as shown
in Listing 15.11.
CLASS zcl_monsters DEFINITION.
PUBLIC SECTION.
INTERFACES IF_AMDP_MARKER_HDB.
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