3 types of Function modules.
NORMAL FUNCTION MODULE:
Function modules are procedures that are defined in
function groups (special ABAP programs with type F) and can
be called from any ABAP program. Function groups act as
containers for function modules that logically belong
together,Function modules allow you to encapsulate and
reuse global functions in the R/3 System. They are stored
in a central library,Unlike subroutines, you do not define
function modules in the source code of your program.
REMOTE FUNCTION MODULE (RFC):
RFC (Remote Function Call) is an extension of CALL FUNCTION
in a distributed environment. Existing function modules can
be executed from within a remote system (R/2 or R/3) via an
RFC Call. Adding a Destination clause to the CALL FUNCTION
statement does this.
The destination parameter displays an entry in the RFCDES
table (which is defined with t.code SM59). This entry
contains all necessary parameters to conect to and log in
the destination system. The RFC API on OS/2, Windows,
Windows NT and all R/3 based UNIX platforms makes it
possible to use the RFC functionality between an SAP System
and a non SAP System.
UPDATE FUNCTION MODULE:
These function modules are used to update the database
tables. Using the function module in updating the database
table helps in updating the database without any