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Introduction to RFC (Remote Function Call)

What is RFC?

For business applications, it is necessary to communicate and exchange information (in pre-

dened formats) with other systems. Hence, there are well dened mechanisms to enable thiscommunication. S! has also pro"ided us with such mechanism called RFC, which stands for

#Remote Function Call#.

 

$F% is a S! protocol to handle communications between systems to simplify the related

programming. &t is the process of calling a function module which is residing in a di'erent

machine from the caller program. $F%s can be used to call a di'erent program in the same

machine as well, but usually it is used when #calling# and #called# function modules programs arerunning on separate machines.

 

&n S!, $F% &nterface system is used for setting-up $F% connections between di'erent S!

systems, and also between an S! and an external (non-S!) system.

 

Must Know Details About RFC

• S! ses %!&% (%ommon !rogramming &nterface for %ommunication) !rotocol to transfer

data between Systems. &t is S! Specic protocol. $emote Function %all ($F%) is acommunications interface based on %!&-%, but with more functions and easier for application

programmers to use

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•  *he $F% library functions support the % programming language and +isual asic (on

indows platforms)

• $F% connections can always be used across the entire system. *his means that an $F%

connection you ha"e dened in client can also be used from client / (without any

di'erence).

• $F% is the protocol for calling special subroutines (function modules) o"er the networ0.

Function modules are comparable with % functions or !S%1 procedures. *hey ha"e a dened

interface through which data, tables and return codes can be exchanged. Function modules are

managed in the $2 System in their own function library, called the Function uilder.

•  *he Function uilder (transaction S324) pro"ides application programmers with a useful

en"ironment for programming, documenting and testing function modules that can be called

locally as well as remotely. *he $2 System automatically generates the additional code ($F%

stub) needed for remote calls.

•  5ou maintain the parameters for $F% connections using transaction S367. *he $2 System

is also deli"ered with an $F%-S89 (Software 8e"elopment 9it) that uses extensi"e % libraries toallow external programs to be connected to the $2 System.

•  *he only di'erence between a remote call of a function module to another ser"er and a

local call is a special parameter (destination) that species the target ser"er on which the

program is to be executed.

The RFC Advantaes!

$F% helps to reduce the e'orts of programmers, by letting them a"oid the re-de"elopment of

modules and methods at remote systems. &t is capable enough to:

• %on"ert the data into the format understandable by the remote (target) system.

• %all up certain routines which are necessary to start communication with remote system.

• Handle errors that might occur in the process of communication.

T"#es o$ RFC!

%"nchronous

re;uires both the systems (client and ser"er) to be a"ailable at the time of communication or data

transfer. &t is the most common type and is re;uired when result is re;uired immediately after the

execution of s$F%.

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s$F% is a means of communication between systems where ac0nowledgements are re;uired. *he

resources of the Source System wait at the target system and ensure that they deli"er the

messagedata with %98. *he 8ata is consistent and reliable for communication.

 *he issue is if the target system is not a"ailable, the source system resources wait until target

system is a"ailable. *his may lead to the !rocesses of source system to go into Sleep$F%%!&%

3ode at target systems and hence bloc0s these resources.

&sed $or

• For communication between systems

• For communication between S! eb pplication Ser"er to S!

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@ueued $F% is an extension of t$F%. &t also ensures that indi"idual steps are processed in

se;uence.

 *o guarantee that multiple 1s (1ogical nit of or0 *ransaction) are processed in the order

specied by the application. t$F% can be serialiAed using ;ueues (inbound and outbound ;ueues).

Hence the name ;ueued $F% (;$F%). sed For-

•

Extension of the Transactional RFC• For a dened processing sequence

• &mplementation of ;$F% is recommended if you want to guarantee that se"eral

transactions are processed in a predened order.

T"#es o$ RFC Connections %M*+

 

T"#e , - entries specify connection between ! systems. Here, we must specify the host name

&! address. 5ou can, howe"er, specify logon information if desired. *his is applicable for both

type of $F%s, between ! systems and external calls to ! systems

T"#e I ' entries specify ! systems connected to the same data base as the current system.

 *hese entries are pre-dened and cannot be modied. >xample entry name: ws/6B9/=BCD

• ws/6Ehost name

• 9/=Esystem name (data base name)

• CDE*%!-ser"ice name

  T"#e T - destinations are connections to external programs that use the $F% !& to recei"e

$F%s. *he acti"ation type can be either Start  or Registration. &f it is Start , you must specify the

host name and the pathname of the program to be started.

-ow to Con.ure and Test RFC/

 *his tutorial is di"ided into D sections

/. Setup a $F% connection

C. *rusted $F% connection

2. *esting a $F% connection

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D. >rror $esolution

0rocedure to setu# an RFC connection!

>nter *ransaction %ode %M*+

 

&n the S367 screen, you can na"igate through already created $F%s connection with the help of

option tree, which is a menu based method to organiAe all the connections on the basis of

categories.

 

%lic0 the #CREATE# button. &n the next screen , >nter -

• RFC Destination Game of 8estination (could be *arget System &8 or anything rele"ant)

• Connection T"#e here we choose one of the types (as explained pre"iously) of $F%

connections as per re;uirements.

• Descri#tion  *his is a short informati"e description, probably to explain the purpose of

connection.

 

fter you1%A231the connection, the system will ta0e you to #*echnical Settings# tab, where we

pro"ide the following information:

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• Taret -ost Here we pro"ide the complete hostname or &! address of the target system.

• %"stem 4umber  *his is the system number of the target S! system.

• %lic0 Sa"e

 

&n the 15oon and %ecurit"1  *ab, >nter *arget System information

• 5anuae s per the target system#s language

• Client  &n S! we ne"er logon to a system, there has to be a particular client always,therefore we need to specify client number here for correct execution.

• &ser ID and 0assword preferably not to be your own login &8, there should be some

generic &8 so that the connection should not be a'ected by constantly changing end-user &8s

or passwords. Mostly, a user of type System or Communication is used here! !lease note that

this is the ser &8 for the target system and not the source system where we are creating this

connection.

 

%lic0 Sa"e. $F% connection is ready for use

4ote: y default a connection is dened as a$F%. *o dene a connection as t$F% or ;$F% go to

3enu ar - 8estination a$F% options t$F% options I pro"ide inputs as per re;uirements. *o

dene ;$F% , use the special options tab.

Trusted RFC connection

 *here is an option to ma0e the $F% connection as 1Trusted1/ Jnce selected, the calling (trusted)

system doesn#t re;uire a password to connect with target (trusting) system.

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Following are the ad"antages for using trusted channels:

•

%ross-system Single-Sign-Jn facility• !assword does not need to be sent across the networ0

•  *imeout mechanism for the logon data pre"ents misuse.

• !re"ents the mishandling of logon data because of the time-out mechanism.

• ser-specic logon details of the callingtrusted system is chec0ed.

The RFC users must ha"e the required authori#ations in the trusting system $authori#ation

o%&ect S_RFCACL '! *rusted connections are mostly used to connect S! Solution

3anager Systems with other S! systems (satellites)

Testin the RFC Connection

fter the $F%s are created (or sometimes in case of already existing $F%s) we need to test,

whether the connection is established successfully or not.

 

s shown abo"e we go to S367 to choose the $F% connection to be tested and then we expand

drop down menu - K&tilities'6Test'67K. e ha"e three options:

Connection test '6 *his attempts to ma0e a connection with remote system and hence

"alidates &! address Hostname and other connection details. &f both systems are not able to

connect, it throws an error. Jn success it displays the table with response times. *his test is Lust

to chec0 if the calling system is able to reach the remote system.

 

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Authori8ation Test '6 &t is used to "alidate the ser &8 and !assword (pro"ided under #logon

and security# tab for the target system) and also the authoriAations that are pro"ided. &f test is

successful, then same screen will appear as shown abo"e for the connection test.

&nicode Test '6 &t is to chec0 if the *arget system is a nicode or not.

 

Remote 5oon 6 *his is also a 0ind of connection test, in which a new session of the target

system is opened, and we need to specify a login &8 and !assword (if not already mentioned

under #1ogon and Security# tab). &f the user is of type #8ialog# then a dialog session is created. *o

 Lustify the successful connection test, output will be the response times for the communication

pac0ets, else error message will appear.

 

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What went wron?

&f somehow the $F% connection is not established successfully, we can chec0 the logs (to analyAe

the issue) at JS le"el in the #J$9# director. *here we can nd the log les with the naming

con"ention as Kde"(rfc)sequence no!*K and the error description can be read from such les.