RFC in R/3

RFC provides interface shims for different operating systems and platforms, which provide the communication APIs for doing RFC from and to R/3.

SAP R/3 is designed as a multiserver architecture. Therefore, R/3 is equipped with a communication architecture that allows data exchange and communication between individual R/3 application and database servers. This communication channel also enables R/3 to execute programs running on a remotely connected server using RFC technology.

SAP R/3 provides special routines to enable RFC from and to R/3 for several operation systems. For NT and WINDOWS the DLLs are delivered with the SAPGUI Non SAP R/3 programs can access function modules in R/3, which is done by calling an SAP provided interface stem. Interfaces exist for UNIX, Windows and IBM S/390 platforms.

R/3 systems which are tied together via TCP/IP are always RFC capable. One R/3 system can call function modules in a remote RFC system, just as if the function where part of the own calling system.A function module can be called via RFC if the function has RFC enabled. This is a simple flag on the interface screen of the function.

Enabling RFC for a function does not change the function. The only difference between RFC-enabled and standard functions is that RFC functions have some restriction: namely, they cannot have untyped parameters.

A text in SAP is an ordinary document, not a customizing or development object. Therefore, texts are never automatically transported from a development system to a production system. This example helps to copy text into a remote system.

R/3 RFC is not limited to communication between R/3 systems. Every computer providing support for the RFC protocol can be called from R/3 via RFC. SAP provides necessary API libraries for all operating systems which support R/3 and many major programming languages e.g. C++, Visual Basic or Delphi.

Calling a program via RFC on a PC or a UNIX system is very much like calling it in another R/3 system. Indeed, the calling system will not even be able to recognize whether the called program runs on another R/3 or on a PC.

To make a system RFC compliant, you have to run an RFC server program on the remote computer. This program has to have a calling interface which is well defined by SAP. In order to create such a server program, SAP delivers an RFCdevelopment kit along with the SAPGUI.

The RFC call to Windows follows the OLE/ACTIVE-X standard, while UNIX is connected via TCP/IP RFC which is a standard in all TCP-compliant systems.In order to call rfcexec, it has to be defined as a TCP/IP destination in SM59. R/3 comes with two destinations predefined which will call rfcexec either on the R/3 application server SERVER_EXEC or on the front end LOCAL_EXEC.

By specifying another computer name you can redirect the call for RFCEXEC to the named computer. Of course, the target computer needs to be accessible from the R/3 application server (not from the workstation) and have rfcexec installed.The object interface of rfcexec supports two methods only, which are called as remote function call from R/3.


RELATED POSTS

QUEUED RFC
RFC PART 3
RFC PART 2

RFC Remote Function Call

A remote function call RFC enables a computer to execute a program an a different computer within the same LAN, WAN or Internet network. RFC is a common UNIX feature, which is found also in other object-oriented operating systems. R/3 provides special DLLs for WINDOWS, NT and UNIX to allow RFC calls from and to R/3.

A Remote Function Call enables a computer to execute a program an another computer. The called program is executed locally on the remote computer using the remote computer’s environment, CPU and data storage.Remote function call is one of the great achievements of TCP/IP networks. Every computer within the network can accept an RFC-call and decides whether it wants to execute the request. Every modern FTP server implementation includes the RFC calling feature.

A classical network server stores the program code in a central location. When the program is called, the code will be transported via the network to the calling computer workstation and executed on the calling computer, consuming the caller’s resources of CPU, memory and disk.

An RFC calls the program on the remote computer. It is just like stepping over to the remote computer, typing in the program command line with all parameters and waiting for the result to be reported back to the calling computer. The calling computer does not provide any resources other than the parameters specified with the call.Here is again what an RFC does.

• It calls the program on a remote computer and specify parameters if and as necessary.

• The remote computer decides whether to fulfil the request and execute the program.

• Every manipulation done by the called program is effective in the same way as if the program had started on the remote system.

• The calling program task waits meanwhile for the called program to terminate.

• When the RFC program terminates, it returns result values if applicable.

• The called program needs not to be present on the calling computer.

• The called program can be run under a completely different operation system,so you can call a WINDOWS program from UNIX and vice versa.A typical RFC example is the internet with a web browser as the RFC client and the web server as the RFC server. Executing a server applet e.g. via CGI or a JAVA or JAVASCRIPT server side applet is actually a remote function call from the web browser to the HTTP server.If R/3 is doing RFC calls into another system, then it does exactly what a browser does when performing a request on the HTTP or FTP server.

related post

Data Ports ( WE21 ) in idoc

IDoc data can be sent and received through a multitude of different media. In order to decouple the definition of the media characteristics from the application using it, the media is accessed via ports.A port is a logical name for an input/output device. A program talks to a port which is presented to it with a common standard interface. The port takes care of the translation between the standard interface format and the device dependent format.Communication media is defined via a port definition.

Instead of defining the communication path directly in the partner profile, a port number is assigned. The port number then designates the actual medium. This allows you to define the characteristics of a port individually and use that port in multiple profiles. Changes in the port will then reflect automatically to all profiles without touching them.

Typical ports for data exchange :

• Disk file with a fixed name
• Disk file with dynamic names
• Disk file with trigger of a batch routine
• Standard RFC connection via TCP/IP
• A network channel
• TCP/IP FTP destination (The Internet)
• Call to a individual program e.g. EDI converter

Every application should send or receive its data via the logical ports only. This allows you to easily change the hardware and software used to make the physical I/O connection without interfering with the program itself.The transactions used to define the ports are

• WE21 to create the port and assign a logical name, and
• SM59 to define the physical characteristics of the I/O device used.

The difference between the port types is mainly the length of some fields. E.g. does port type 3 allow segment names up to 30 characters in length, while port type 3 is constrained to a maximum segment name of 8 characters.


related post

ABAP IDOC'S INTRODUCTION
IDOC'S MESSAGE CONTROL
DIFFERENCE BETWEEN IDOC AND BAPI
IDOC'S OUT BOUND TRIGGERING
ERP Master data and data warehouse concept

Defining the partner profile for ALE IDOC

The transaction WE20 is used to set up the partner profile.

WE20 :

The profiles are defined with transaction WE20, which is also found in the EDI master menu WEDI. From there you need to specify partner and partner type and whether you define a profile for inbound or outbound. Additionally, you may assign the profile to a NAST message type.

Partner type :

e.g. : LI=Supplier ,CU=Customer, LS=Logical system

The partner type defines from which master data set the partner number originates.The partner types are the ones which are used in the standard applications for SD, MM or FI. The most important types for EDI are LI (=Lieferant, supplier), CU (Customer) or LS (Logical system). The logical system is of special interest when you exchange data with computer subsystems via ALE or other RFC means.

Inbound and outbound definitions :

For every partner and every direction of communication, whether you receive or send IDocs, a different profile is maintained. The inbound profile defines the processing routine. The outbound profile defines mainly the target, where to send the data .

Link message type to outbound profile :

If you send IDocs out of an application’s messaging, i.e. a communication via the NAST table, then you have to link the message type with an IDoc profile. This is also done in transaction WE20.

Inbound profiles determine the processing logic :

The processing code is a logical name for the processing function module or object method. The processing code is used to uniquely determine a function module that will process the received IDoc data. The inbound profile will point to a processing code.

Related posts


Partner Profiles and Ports

R/3 defines partner profiles for every EDI partner. The profiles are used to declare the communication channels, schedule, and conditions of processing.Partner profiles declare the communication medium to be used with a partner.Ports define the physical characteristics of a communication channel.If you define an ALE scenario for your IDoc partners, you can use the ALE automated partner profile generation ( → ALE ).

IDoc Type and Message Type

An IDoc file requires a minimum of accompanying information to give sense to it. These are the message type and the IDoc type. While the IDoc type tells you about the fields and segments of the IDoc file, the message type flags the context under which the IDoc was sent.

IDoc type signals syntactical structure :

A receiver of an IDoc must know the exact syntactical structure of the data package received. Naturally, the receiver only sees a text file with lines of characters.In order to interpret it, it is necessary to know which segment types the file may contain and how a segment is structured into fields. SAP sends the name of the IDoc type in the communication header.

The IDoc type describes the file structure. The IDoc type is defined and viewable with transaction WE30.

Examples of IDoc types are MATMAS01, ORDERS01, COND_A01 or CLSMAS01.

The message type is an identifier that tags the IDoc to tell the receiver how the IDoc is meant to be interpreted. It is therefore the tag for the semantic content of the IDoc.

Examples of message types are MATMAS, ORDERS, COND_A or CLSMAS.

The combination of IDoc type and message type gives the IDoc the full meaning. Theoretically, you could define only a single IDoc type for every IDoc you send. Then, all IDocs would have the same segments and the segments would always have the same field structure. According to the context some of the record fields are filled; others are simply void. Many antiquated interfaces are still working that way.Typical combinations of IDoc and message types are the following:

Message Type IDoc Type
Sales order, older format ORDERS ORDERS01
Sales order, newer format ORDERS ORDERS02
Purchase Requisition PURREQ ORDERS01

The example shows you that sales orders can be exchanged in different file formats. There may be some customers who accept the latest IDoc format ORDERS02, while others still insist on receiving the old format ORDERS01.

The IDoc format for sales orders would also be used to transfer a purchase requisition. While the format remains the same, the different message type signals that it is not an actual order but a request.Partner profiles play an important role in EDI communications. They are parameter files which store the EDI partner dependent information.Partner profiles define the type of data and communication paths of data to be exchanged between partner .

When data is exchanged between partners, it is important that sender and receiver agree on the exact syntax and semantics of the data to be exchanged. This agreement is called a partner profile and tells the receiver the structure of the sent file and how its content is to be interpreted.For any combination of message type and receiving partner, a profile is maintained .

The following information is defined with the partner profile.

• IDoc type and message type as key identifier of the partner profile
• Names of sender and receiver to exchange the IDoc information for the respective IDoc and message type .

• Logical port name via which the sender and receiver, resp. will communicate

The communication media is assigned by the profile.

If you exchange e.g. sales orders with partners, you may do this via different media with different customers. There may be one customer to communicate with you via TCP/IP (the Internet) while the other still insists on receiving diskette files.

Profiles cannot be transported :

They must be defined for every R/3 client individually. They cannot be transported using the R/3 transport management system. This is because the profile contains the name of the sending system, which is naturally different for consolidation and production systems.

Profiles define the allowed EDI connections :

The profiles allow you to open and close EDI connection with individual partners and specify in detail which IDocs are to be exchanged via the interface.

Profiles can also used to block an EDI communication :

The profile is also the place to lock permanently or temporarily an IDoc communication with an EDI partner. So you shut the gate for external communication with the profile.

RELATED POSTS

Converting Data into IDoc Segment Format

The physical format of the IDocs records is always the same. Therefore, the application data must be converted into a 1000 character string.

Fill the data segments which make up the IDoc :

An IDoc is a file with a rigid formal structure. This allows the correspondents to correctly interpret the IDoc information. Were it for data exchange between SAPsystems only, the IDoc segments could be simply structured like the correspondent DDIC structure of the tables whose data is sent.

However, IDocs are usually transported to a variety of legacy systems which do not run SAP. Both correspondents therefore would agree on an IDoc structure which is known to the sending and the receiving processes.

Transfer the whole IDoc to an internal table, having the structure of EDIDD :

All data needs to be compiled in an internal table with the structure of the standard SAP table EDIDD. The records for EDIDD are principally made up of a header string describing the segment and a variable length character field (called SDATA) which will contain the actual segment data.

FORM PACK_LINE TABLES IDOC_DATA USING 'THEAD' E_THEAD.

TABLES: THEAD.

MOVE-CORRESPONDING E:THEAD to Z1THEAD.
MOVE ‚Z1THEAD’ TO IDOC_DATA-SEGNAM.
MOVE Z1THEAD TO IDOC_DATA-SDATA.
APPEND IDOC_DATA.
ENDFORM.“

Fill control record :

Finally, the control record has to be filled with meaningful data, especially telling the IDoc type and message type.

IF IDOC_CONTRL-SNDPRN IS INITIAL.

SELECT SINGLE * FROM T000 WHERE MANDT EQ SY-MANDT.
MOVE T000-LOGSYS TO IDOC_CONTRL-SNDPRN.

ENDIF.
IDOC_CONTRL-SNDPRT = 'LS'.

* Trans we20 -> Outbound Controls muss entsprechend gesetzt werden.
* 2 = Transfer IDoc immediately
* 4 = Collect IDocs

IDOC_CONTRL-OUTMOD = '2'. "1=imediately, subsystem
CLEAR IDOC_CONTRL.
IDOC_CONTRL-IDOCTP = 'YAXX_TEXT'.
APPEND IDOC_CONTRL.

RELATED POSTS

Developing an Outbound IDoc Function

This is an individual coding part where you need to retrieve the information from the database and prepare it in the form the recipient of the IDoc will expect the data.

Read data to send :

The first step is reading the data from the database, the one you want to send.

FUNCTION Y_AXX_COOKBOOK_TEXT_IDOC_OUTB.

*"----------------------------------------------------------------------
*"*"Lokale Schnittstelle:

*" IMPORTING

*" VALUE(I_TDOBJECT) LIKE THEAD-TDOBJECT DEFAULT 'TEXT'
*" VALUE(I_TDID) LIKE THEAD-TDID DEFAULT 'ST'
*" VALUE(I_TDNAME) LIKE THEAD-TDNAME
*" VALUE(I_TDSPRAS) LIKE THEAD-TDSPRAS DEFAULT SY-LANGU

*" EXPORTING

*" VALUE(E_THEAD) LIKE THEAD STRUCTURE THEAD

*" TABLES

*" IDOC_DATA STRUCTURE EDIDD OPTIONAL
*" IDOC_CONTRL STRUCTURE EDIDC OPTIONAL
*" TLINES STRUCTURE TLINE OPTIONAL
*" EXCEPTIONS
*" FUNCTION_NOT_EXIST
*" VERSION_NOT_FOUND
*"----------------------------------------------------------------------
CALL FUNCTION 'READ_TEXT'

EXPORTING

ID = ID
LANGUAGE = LANGUAGE
NAME = NAME
OBJECT = OBJECT
TABLES
LINES = LINES.

* now stuff the data into the Idoc record format
PERFORM PACK_LINE TABLES IDOC_DATA USING 'THEAD' E_THEAD.
LOOP AT LINES.
PERFORM PACK_LINE TABLES IDOC_DATA USING 'THEAD' LINES.
ENDLOOP.
ENDFUNCTION.

Converting Data into IDoc Segment Format :

The physical format of the IDocs records is always the same. Therefore, the application data must be converted into a 1000 character string.

Fill the data segments which make up the IDoc :

An IDoc is a file with a rigid formal structure. This allows the correspondents to correctly interpret the IDoc information. Were it for data exchange between SAPsystems only, the IDoc segments could be simply structured like the correspondent DDIC structure of the tables whose data is sent.

However, IDocs are usually transported to a variety of legacy systems which do not run SAP. Both correspondents therefore would agree on an IDoc structure which is known to the sending and the receiving processes.

Transfer the whole IDoc to an internal table, having the structure of EDIDD :

All data needs to be compiled in an internal table with the structure of the standard SAP table EDIDD. The records for EDIDD are principally made up of a header string describing the segment and a variable length character field (called SDATA) which will contain the actual segment data.

FORM PACK_LINE TABLES IDOC_DATA USING 'THEAD' E_THEAD.
TABLES: THEAD.
MOVE-CORRESPONDING E:THEAD to Z1THEAD.
MOVE ‚Z1THEAD’ TO IDOC_DATA-SEGNAM.
MOVE Z1THEAD TO IDOC_DATA-SDATA.
APPEND IDOC_DATA.
ENDFORM.“

Fill control record :

Finally, the control record has to be filled with meaningful data, especially telling the IDoc type and message type.

IF IDOC_CONTRL-SNDPRN IS INITIAL.
SELECT SINGLE * FROM T000 WHERE MANDT EQ SY-MANDT.
MOVE T000-LOGSYS TO IDOC_CONTRL-SNDPRN.
ENDIF.

IDOC_CONTRL-SNDPRT = 'LS'.

* Trans we20 -> Outbound Controls muss entsprechend gesetzt werden.
* 2 = Transfer IDoc immediately
* 4 = Collect IDocs
IDOC_CONTRL-OUTMOD = '2'. "1=imediately, subsystem
CLEAR IDOC_CONTRL.
IDOC_CONTRL-IDOCTP = 'YAXX_TEXT'.
APPEND IDOC_CONTRL.

RELATED POSTS

Creation of the IDoc Data

R/3 provides a sophisticated IDoc processing framework. This framework determines a function module which is responsible for creating or processing the IDoc.

Function module to generate the IDoc :

The kernel of the IDoc processing is always a distinct function module. For the outbound processing, the function module creates the IDoc and leaves it in an internal table, which is passed as an interface parameter.During inbound processing the function module receives the IDoc via an interface parameter table. It would interpret the IDoc data and typically update the database either directly or via a call transaction.

Function are called dynamically :

The function modules are called dynamically from a standard routine. Therefore, the function must adhere to a well-defined interface. 

Function group EDIN with useful routines :

You may want to investigate the function group EDIN, which contains a number of IDoc handler routines and would call the customised function.

Copy and modify existing routines :

The easiest way to start the development of an outbound IDoc function module is to copy an existing one. There are many samples in the standard R/3 repository'; most are named IDOC_OUTBOUND* or IDOC_OUTPUT*

Outbound sample functions are named like IDOC_OUTPUT* :

FUNCTION IDOC_OUTPUT_ORDERS01

Inbound sample functions are named like IDOC_INPUT* :

FUNCTION IDOC_INPUT_ORDERS01

Outbound sample functions for master data are named like MASTERIDOC_INPUT* :

FUNCTION MASTERIDOC_CREATE_MATMAS

Interface Structure of IDoc Processing Functions

To use the standard IDoc processing mechanism, the processing function module must have certain interface parameters because the function is called dynamically from a standard routine.The automated IDoc processor will call your function module from within the program RSNASTED, usually either from the FORM ALE_PROCESSING or EDI_PROCESSING.In order to be compatible with this automated call, the interface of the function module must be compliant.

FUNCTION Z_IDOC_OUTBOUND_SAMPLE.

*" IMPORTING

*" VALUE(FL_TEST) LIKE RS38L-OPTIONAL DEFAULT 'X'
*" VALUE(FL_COMMIT) LIKE RS38L-OPTIONAL DEFAULT SPACE

*" EXPORTING

*" VALUE(F_IDOC_HEADER) LIKE EDIDC STRUCTURE EDIDC

*" TABLES

*" T_IDOC_CONTRL STRUCTURE EDIDC
*" T_IDOC_DATA STRUCTURE EDIDD

*" CHANGING

*" VALUE(CONTROL_RECORD_IN) LIKE EDIDC STRUCTURE EDIDC
*" VALUE(OBJECT) LIKE NAST STRUCTURE NAST

*" EXCEPTIONS

*" ERROR_IN_IDOC_CONTROL
*" ERROR_WRITING_IDOC_STATUS
*" ERROR_IN_IDOC_DATA
*" SENDING_LOGICAL_SYSTEM_UNKNOWN
*" UNKNOWN_ERROR

Inbound functions are also called via a standard mechanism.

FUNCTION IDOC_INPUT_SOMETHING.

*" IMPORTING

*" VALUE(INPUT_METHOD) LIKE BDWFAP_PAR-INPUTMETHD
*" VALUE(MASS_PROCESSING) LIKE BDWFAP_PAR-MASS_PROC

*" EXPORTING

*" VALUE(WORKFLOW_RESULT) LIKE BDWFAP_PAR-RESULT
*" VALUE(APPLICATION_VARIABLE) LIKE BDWFAP_PAR-APPL_VAR
*" VALUE(IN_UPDATE_TASK) LIKE BDWFAP_PAR-UPDATETASK
*" VALUE(CALL_TRANSACTION_DONE) LIKE BDWFAP_PAR-CALLTRANS

*" TABLES

*" IDOC_CONTRL STRUCTURE EDIDC
*" IDOC_DATA STRUCTURE EDIDD
*" IDOC_STATUS STRUCTURE BDIDOCSTAT
*" RETURN_VARIABLES STRUCTURE BDWFRETVAR
*" SERIALIZATION_INFO STRUCTURE BDI_SER

RELATED POSTS

IDOC design and Processing

IDocs are usually created in a four step process: retrieving the data, converting it to IDoc format, adding a control record, and delivering the IDoc to a port.

Collect data from R/3 database :

This is the single most important task in outbound processing. You have to identify the database tables and data dependencies which are needed in the IDoc to be sent.The smartest way is usually to select the data from the database into an internal table using SELECT * FROM dbtable INTO itab ... WHERE ...
Wrap data in IDoc format :

The collected data must be transformed into ASCII data and filled into the predefined IDoc segment structures. The segment definitions are done with transaction WE31 and the segments allowed in an IDoc type are set up in transaction WE30. Segments defined with WE31 are automatically created as SAP DDIC structures. They can be viewed with SE11, however, they cannot be edited.

Create the IDoc control record :

Every IDoc must be accompanied by a control record which must contain at least the Idoc type to identify the syntactical structure of the data and the name and role of the sender and the receiver. This header information is checked against the partner definitions for outbound. Only if a matching partner definition exists, can the IDoc be sent. Partner definitions are set up with transaction WE20.

Send data to port :

When the partner profile check matches, the IDoc is forwarded to a logical port, which is also assigned in the partner profile. This port is set up with transaction
WE21 and defines the medium to transport the IDoc, e.g. file or RFC.
The RFC destinations are set up with transaction SM57 and must also be entered in table TBDLS with an SM31 view. Directories for outbound locations of files are set up
with transaction FILE and directly in WE21. It also allows the use of a function
module which generates file names. Standard functions for that purpose begin like
EDI_FILE*.

How SAP Standard Processes Inbound IDocs :

When you receive an IDoc the standard way, the data is stored in the IDoc base and a function module is called, which decides how to process the received information.

EDID4 - Data :

Data is stored in table EDID4 (EDID3 up to release 3.xx, EDIDD up to release 2.xx)

EDIDC - Control Record :

An accompanying control record with important context and administrative
information is stored in table EDIDC.

Event signals readiness :

After the data is stored in the IDoc base tables, an event is fired to signal that there is an IDoc waiting for processing. This event is consumed by the IDoc handler, which decides, whether to process the IDoc immediately, postpone processing, or decline activity for whatever reason.

EDIFCT - Processing function :

When the IDoc processor thinks it is time to process the IDoc it will search the table EDIFCT , where it should find the name of a function module which will be called to process the IDoc data.

This function module is the heart of all inbound processing. The IDoc processor will
call this routine and pass the IDoc data from EDID4 and the control record from
EDIDC for the respective IDoc.

Function has a fixed interface :

Because this routine is called dynamically, it must adhere to a strict convention All
function interface parameters must exactly match the calling convention.

EDIDS - Status log :

The processing steps and their respective status results are stored in table EDIDS.

Status must be logged properly :

In addition, the routine has to properly determine the next status of the IDoc in table EDIDS; usually it will be EDIDS-STATU = 53 for OK or 51 for error.

(74)

RELATED POSTS

Dispatching ALE IDocs for Change Pointers

Change pointers must be processed by an ABAP, e.g. RBDMIDOC.

The actual distribution of documents from change pointers must be done by an ABAP, which reads the change pointers and processes them. The standard ABAP for that is RBDMIDOC. For recurring execution it can be submitted in a scheduled job using SM35 .

It then calls dynamically a function module whose name is stored in table TBDME for each message type.

Call Function Tbdme-Idocfbname
Exporting
Message_Type = Mestyp
Creation_Date_High = Date
Creation_Time_High = Time
Exceptions
Error_Code_1.

Example :

A complex example for a function module, which collects the change pointers, can be examined in:

MASTERIDOC_CREATE_SMD_DEBMAS .

This one reads change pointers for debtors (customer masters). During the processing, it calls the actual IDoc creating module

MASTERIDOC_CREATE_DEBMAS .

To summarize the change pointer concept

• Change pointers record relevant updates of transaction data
• Change pointers are written separate from the change documents, while at the same time
• Change pointers are evaluated by a collector run

BDCPS : Change pointer: Status

BDCP : Change pointer

BDCPV : A view with BDCP and BDCPS combined: Change pointer with status

TBDA2 :

Declare activate message types for change pointers with view V_TBDA2.or transaction BD50 or .

SALE -> Activate change pointers for message types

TBD62 : The view V_TBD62 defines those fields which are relevant for change pointer creation. The table is evaluated by the CHANGE_DOCUMENT_CLOSE function.The object is the same used by the change document. To find out the object name,look for CHANGE_DOCUMENT_CLOSE in the transaction you are inspecting or see table CDHDR for traces.

Tables involved in change pointers processing :

Object
Table name
Field
DEBI
KNA1
NAME3
DEBI
Kann1
ORT01
DEBI
Kann1
REGIO


RELATED POSTS

ALE Change Pointers

Applications which write change documents will also try to write change pointers for ALE operations. These are log entries to remember all modified data records relevant for ALE.Most applications write change documents. These are primarily log entries in the tables CDHDR and CDPOS.

Change documents remember the modified fields made to the database by an application. They also remember the user name and the time when the modification took place.The decision whether a field modification is relevant for a change document is triggered by a flag of the modified field’s data element. You can set the flag with SE11 by modifying the data element.

For the purpose of distributing data via ALE to other systems, you may want to choose other fields, which shall be regarded relevant for triggering a distribution.Therefore R/3 introduced the concept of change pointers, which are nothing else than a second log file specially designed for writing the change pointers which are meant to trigger IDoc distribution via ALE.So the change pointers will remember the key of the document every time when a relevant field has changed.

Change pointers are then evaluated by an ABAP which calls the IDoc creation, for every modified document found in the change pointers.The Change pointers are written from the routine CHANGEDOCUMENT_CLOSE when saving the generated change document. So change pointers are automatically written when a relevant document changes.

The following function is called from within CHANGEDOCUMENT_CLOSE in order to write the change pointers.

CALL FUNCTION 'CHANGE_POINTERS_CREATE'
EXPORTING
change_document_header = cdhdr
TABLES
change_document_position = ins_cdpos.

Activation of change pointer update :

Change pointers are log entries to table BDCP which are written every time a transaction modifies certain fields. The change pointers are designed for ALE distribution and written by the function CHANGE_DOCUMENT_CLOSE.

Change pointers are written for use with ALE. There are ABAPs like RBDMIDOC which can read the change pointers and trigger an IDoc for ALE distribution.The change pointers are mainly the same as change documents. They however can be set up differently, so fields which trigger change documents are not necessarily the same that cause change pointers to be written.

In order to work with change pointers there are two steps to be performed

1) Turn on change pointer update generally

2) Decide which message types shall be included for change pointer update R3 allows to activate or deactivate the change pointer update. For this purpose it maintains a table TBDA1. The decision whether the change pointer update is active is done with a Function Ale_Component_Check

This check does nothing else than to check, if this table has an entry or not. If there is an entry in TBDA1, the ALE change pointers are generally active. If this table is empty, change pointers are turned off for everybody and everything, regardless of the other settings.

The two points read like you had the choice between turning it on generally or selectively. This is not the case: you always turn them on selectively. The switch to turn on generally is meant to activate or deactivate the whole mechanism.The change pointers which have not been processed yet, can be read with a function module.

Call Function 'CHANGE_POINTERS_READ'

The ABAP RBDMIDOC will process all open change pointers and distribute the matching IDocs.When you want to send out an IDoc unconditionally every time a transaction updates, you better use the workflow from the change documents.

RELATED POSTS

Work flow based outbound Idoc's

Unfortunately, there are application that do not create messages. This is especially true for master data applications. However, most applications fire a workflow event during update,which can easily be used to trigger the IDoc distribution.

Many SAP R/3 applications issue a call to the function SWE_EVENT_CREATE during update. This function module ignites a simple workflow event.Technically a workflow event is a timed call to a function module, which takes the issuing event as the key to process a subsequent action.

If an application writes regular change documents (ger.: Ă„nderungsbelege) to the database, it will issue automatically a workflow event. This event is triggered from within the function CHANGEDOCUMENT_CLOSE.

The change document workflow event is always triggered, independent of the case whether a change document is actually written.In order to make use of the workflow for IDoc processing, you do not have to go through the cumbersome workflow design procedure as it is described in the workflow documentation. For the mentioned purpose, you can register the workflow handler from the menu, which says Event Coupling from the BALD transaction.

Triggering the IDoc from a workflow event has a disadvantage: if the IDoc has to be repeated for some reason, the event cannot be repeated easily. This is due to the nature of a workflow event, which is triggered usually from a precedent action.

Therefore you have to find an own way how to make sure that the IDoc is actually generated, even in the case of an error. Practically this is not a very big problem for IDocs. In most cases the creation of the IDoc will always take place. If there is a problem, then the IDoc would be stored in the IDoc base with a respective status. It will shown in transaction WE05 and can be resend from there.

Workflow Event From Change Document:

Most application fire a workflow event from the update routine by calling the function

FUNCTION swe_event_create

You can check if an application fires events by activating the event log from transaction SWLD. Calling and saving a transaction will write the event’s name and circumstances into the log file.If an application does not fire workflow events directly, there is still another chance that a workflow may be used without touching the R/3 original programs.

Every application that writes change documents triggers a workflow event from within the function module CHANGEDOCUMENT_CLOSE, which is called form the update processing upon writing the change document. This will call the workflow processor.

FUNCTION swe_event_create_changedocument:

Both workflow types are not compatible with each other with respect to the function modules used to handle the event.Both will call a function module whose name they find in the workflow linkage tables. swe_event_create will look in table SWETYPECOU while

swe_event_create_changedocument would look in SWECDOBJ for the name of the function module.If a name is found, the function module will then be called dynamically. This is all to say about the linkage of the workflow.The dynamic call looks like the following.

CALL FUNCTION swecdobj-objtypefb
EXPORTING
changedocument_header = changedocument_header
objecttype = swecdobj-objtype
IMPORTING
objecttype = swecdobj-objtype
TABLES
changedocument_position = changedocument_position.

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IDOC'S OUTBOUND TRIGGER PART 3

Sending IDocs Via RSNASTED

Standard R/3 provides you with powerful routines, to trigger, prepare and send out IDocs in a controlled way. There are only a few rare cases, where you do not want to send IDocs the standard way.

The ABAP RSNAST00 is the standard routine to send IDocs from entries in the message control. This program can be called directly, from a batch routine with variant or you can call the FORM einzelnachricht_screen(RSNAST00) from any other program, while having the structure NAST correctly filled with all necessary information.

If there is an entry in table NAST, RSNAST00 looks up the associated processing routine in table TNAPR. If it is to send an IDoc with standard means, this will usually be the routine RSNASTED(EDI_PROCESSING) or RSNASTED(ALE_PROCESSING) in the case of ALE distribution.RSNASTED itself determines the associated IDoc outbound function module, executes it to fill the EDIDx tables and passes the prepared IDoc to the port.

You can call the standard processing routines from any ABAP, by executing the following call to the routine. You only have to make sure that the structure NAST is declared with the tables statement in the calling routine and that you fill at least the key part and the routine (TNAPR) information before.

TABLES NAST.
NAST-MANDT = SY-MANDT.
NAST-KSCHL = 'ZEDIK'.
NAST-KAPPL = 'V1'.
NAST-OBJKY = '0012345678'.
NAST-PARNR = 'D012345678'.
PERFORM einzelnachricht_screen(RSNAST00).

Calling einzelnachricht_screen determines how the message is processed.If you want to force the IDoc-processing you can call it directly:

TNAPR-PROGN = ''.
TNAPR-ROUTN = 'ENTRY'.
PERFORM edi_processing(RSNASTED).

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