graphic:
• ALE: Application Link Enabling
• BAPI: Business Application Programming Interface
• CPI-C: Common Program Interface Communication
• EDI: Electronic Data Interchange
• HTTP: HyperText Transfer Protocol
• LU 6.2: Logical Unit Type 6.2
• RFC: Remote Function Call
• OLE: Object Linking and Embedding
• SMTP: Simple Mail Transfer Protocol
• SOAP: Simple Object Access Protocol
• TCP/IP: Transmission Control Protocol / Internet Protocol
• XML: Extensible Markup Language
Remote Function Call
The Remote Function Call interface is an SAP interface protocol based on CPI-C
and TCP/IP. It simplifies the programming of communication processes between
different systems. RFCs enable you to call and execute predefined functions in a
remote system – or within the same system. RFCs manage the communication
process, parameter transfer and error handling.
RFC describes an interface, not the programming language in which the function
runs. You can also use RFCs to call functions in non-SAP systems. The procedure
for RFC communication between two SAP systems is that the calling system uses
an RFC definition in the system called to access a specific function.
This function is normally a remote-enabled function module. You can also,
depending on the release, use RFC to call functions in SAP R/2 systems.
If you want to start external programs remotely, you need an RFC interface outside
the SAP system. This could be, for example, a simple Dynamic Link Library
(DLL). Every RFC interface is bidirectional, so external programs can also use
RFC to access functions in SAP systems.
Note: All function modules (including those that are remote-enabled)
are created, together with their import and export parameters, using the
Function Builder. You can call the Function Builder using Tools → ABAP
Workbench → Development → Function Builder or using transaction
code SE37.
To call an RFC module from an SAP system, you need to know the import
and export parameters (defined in the Function Builder), and there must be a
technical connection between the two systems. This connection is called an RFC
connection or an RFC destination.
You can manage your RFC connections using Tools → Administration →
Administration → Network → RFC Destinations or using transaction SM59.
In the above graphic you can see, on the left side, the calling system, in which
an RFC destination named DEST has been created. An RFC destination in
transaction SM59 should not be confused with an SAP system, since an RFC
connection can only point to one specific client in an SAP system. These are
therefore also referred to as connections between logical systems; this term is
used, above all, in the ALE environment.
This also means that you can have at least as many RFC connections between two
systems as there are clients in the target system. Since you can specify a logon
user for the destination in each RFC connection, you can therefore also access
clients in the target system several times, for example, with a different logon user
each time. If you need a bidirectional RFC connection between two systems, that
is, that the system called can also execute RFC modules in the calling system, then
you need to set up an equivalent second RFC connection in the system called.
Hint: When you are defining RFC destinations, RFC connections are
• Addressed to one client, when they are pointing at an SAP system
• Accessible from all clients in the system
In ABAP, you use RFCs to call a function module in another system as follows:
CALL FUNCTION
DESTINATION
EXPORTING ...
IMPORTING ...
The function to be executed in the target system is named. The name of the target
must refer to one of the RFC connections available. When you are creating an
RFC connection, you can specify logon data for the target system; if you do not do
this, you need to enter logon parameters when you start the RFC. Exporting
and Importing are used to pass parameters to the target function and to receive
the returned parameters. The function called in the target system is executed using
the user ID entered for the connection.
Note: You can also create RFC connections for which the user of the user
making the call is used in the target system. That means different users
can use the same connection in the target system. This procedure is also
called Trusted RFC. It is, of course, a prerequisite that identical users are
created in the source and target systems. Trusted RFC is explained in the
course ADM960 - Security in SAP System Environments.
The RFC has become the most important interface in the SAP environment. Some
special RFC modules, which follow certain conventions, are also known as BAPIs
(Business Application Programming Interfaces).
BOR and BAPIs
A Business Application Programming Interface (BAPI) is a standardized
programming interface that facilitates internal and external access to business
processes and data in SAP systems. BAPIs are defined in the Business Object
Repository as methods of SAP business objects and enable an object-oriented
view of business data in an SAP system. Functions that can be called using BAPIs
are normally implemented and stored in the ABAP Workbench Function Builder
as RFC-enabled function modules. You can display an overview of available
BAPIs in the BOR, for example, using the Business Object Repository pushbutton
in the Business Object Builder (Tools → ABAP Workbench → Development →
Business Object Builder), transaction SWO1. You can access the BOR directly
using transaction code BAPI.
BAPIs, which represent methods for business objects in an SAP system, are used
in a variety of contexts. Here are some possible uses for BAPIs:
• To link business processes across system boundaries (for example, when
using ALE)
• Used by SAP to integrate various solutions in the framework of mySAP
Business Suite
• To connect an SAP system to the Internet
• Used in conjunction with SAP Business Workflow
• To connect to external programs
Note: BAPIs are created and tested in exactly the same way as other
function modules, using the Function Builder, transaction SE37, and are
then defined as BAPIs in the BOR.
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