Modularization in ABAP

The different modularization techniques available are
1) Include programs
2) Macros
3) Function Modules
4) Subroutines
5) Methods

What is the use of modularization?
1) Improves readability. That means, easy to read
2) Re-usability, the procedures can be used in other programs as well
3) Encapsulation of data
4) Reduces code redundancy, i.e. Avoids duplication of code

How to create Function Module?
We can create function modules by using function builder. The transaction code
for function builder is SE37.

Is it necessary to attach the function module to a function group?
Yes, every function module must be attached to a function group. That means
function group acts as a container. A single function group may contain one or
more function modules which are logically related.

How many types of function modules are there?
There are two types of function modules –
1) Normal
2) Remote (RFC)

How RFC function module differs from normal function module?
RFC stands for remote function call. As the name itself reveals, this function
module can be called remotely by using RFC destination. Here remote means,
external system, it may be a SAP system or Non-SAP system like Java system.

What are the advantages of function modules?
As we discussed above, it is one of the modularization techniques which helps
code re-usability. We can handle exceptions using function modules.

How to know whether a given function module is normal or RFC function module?
1) Go to SE37.
2) Enter the name of the function module you are provided.
3) Click on DISPLAY
4) Choose Attributes tab
5) Under this tab, you can see Processing Type block.
6) If remote-enabled module is checked, then it is RFC otherwise normal function
module.

How many types of RFCs are there?
There are five types of RFCs-
1) Synchronous RFC
2) Asynchronous RFC
3) Transactional RFC
4) Queued RFC
5) Parallel RFC
Synchronous RFC:
It is the very common method used in real business scenarios. Both the client
and server must be available in this type of RFC.
The advantage is that you can get the result immediately, which means the RFC
function module gives result or output immediately.
The syntax is
CALL FUNCTION DESTINATION name>