Creating a Planning Requirement in Transportation

The planning requirement for planning deliveries can be created with the functions described in Outbound Delivery . The procedure can be carried out either as an online transaction, or as a background job, using message control.

Saving the Data in the ALE Layer

Within the same process (LUW, Logical Unit of Work) the data is formatted in the form of repository (data dictionary) structures by the ALE level function module. These structures are called IDocs (Intermediate Document). The IDocs created are saved in the database.

You can find exact information on the structure and definition of an IDoc under IDoc Description and Description of the IDoc Segments, Fields and Domain Values .

Communication Structure and Transmission of the IDocs

Transmission of the IDoc is carried out asynchronously to the creation of the IDoc, that is, after the IDoc is created, transmission is carried out by ALE. An IDoc can be transmitted directly, or combined first and then sent as part of a package of several IDocs.

During IDoc transmission the ALE uses transactional Remote Function Call (tRFC). A remote shell is started in the subsystem and a C program is called to which the function to be called is transferred within the program. The underlying technique that allows transmission to be carried out correctly according to the log, is described above as an RFC layer. From the program side, a library of C development programs is provided.

For further information on the creation of the C Program and further system settings, see the following sections and the documentation in the RFC libraries.

Subsystem Tasks

The C program for receiving the data must be provided on the subsystem. There is also a sample program. This is supported by the RFC library that you receive from SAP as a certification partner (RFC SDK, Remote Function Call Software Development Kit).

The program must save the data after receiving it before the receipt confirmation is sent back to the SAP system. Then, data processing can start in the subsystem. SAP recommends this intermediate saving procedure, which allows communication of processing logic to be carried separately on the subsystem.

Also, the subsystem provides status administration for the data that is received. This prevents duplicated processing. You should also note that the subsystem must be able to recognize if an IDoc has already been transmitted once by the SAP system. This is made possible by the unique transaction ID for each communication procedure (seealso technical documentation for the RFC).

As well as the transaction ID, the IDoc number can also be used to recognize that an IDoc has already been transferred. The IDoc number is only unique within a given client of an SAP system. If communication is carried out with several clients and/or several SAP systems, then the IDoc can not be identified using only the IDoc number.

Error Processing in Communication

During transmission, the following problems usually occur:

Posting termination in the application (e.g. when creating a planning requirement)

In this case, the error is not critical for communication, because no IDoc can be created without a planning requirement. Both postings are carried out in the same LUW and are therefore posted synchronously.

Formatting and Transmitting Shipment Data

The primary task of the subsystem is to optimize planning of shipments from the planning requests that have been transmitted from the SAP system. Fully planned shipments must be transmitted back to the SAP system using the communication path provided (transactional RFC). The subsystem carries out the following tasks within the framework of communication with the SAP system:

Intermediate Storage of Data and Formatting for IDoc

The subsystem shipment data must be saved in an IDoc-specific data structure. For information on the definition and structure of the different IDocs, see sections IDoc Description and Description of the IDoc Segments, Fields and Domain Values .

Calling a Central Function Module in the SAP System using the Transfer Program

You need the RFC library for programming support for the transfer program too. The central function module belongs to the ALE layer.

Several IDocs can be transferred in one communication procedure - that is, when an SAP function module is called once.

Updating After IDoc Transmission

During transmission, the subsystem must provided status administration for the transmitted data. If the IDoc is transmitted unsuccessfully, then it must be transmitted again later.

On the SAP side, duplicated transfer ofIDocs must be avoided. This is where the transaction ID is used. This is defined by SAP for each communication procedure. The data that are transferred by the subsystem must always be transmitted with this transaction ID (see also technical documentation on the RFC). The same transaction ID must be entered for subsequent retransmissions.

The IDoc number is not used by the SAP system to check duplicated transfer.

Receipt and Posting of Data

ALE receives the IDoc and writes it into the database. After this intermediate saving procedure, a confirmation of receipt is sent back to the subsystem. The IDoc is then forwarded to the application (asynchronously with regards to receipt) where processing is carried out.

The SAP application that carries out the creation, changing and deletion of a shipment document, sends a status back to ALE for each IDoc. This IDoc status is the basis for processing any possible errors.

Error Processing

The following errors may occur:

Connection can not be made at present

The subsystem should use status administration to ensure that subsequent posting can be carried out.

Error in the ALE layer

An IDoc was created, but processing has not commenced

This error occurs (as in transmission from the SAP system), if the IDoc received is syntactically incorrect or if the partner profile for inbound processing is missing for the sender and the message type of this IDoc. For more information on this error see section SAP System Settings and Modifications.

Error in the Application (for example, when posting the transfer request)

This is a question of a logical error in the application. A message is issued to a planning position with the IDoc status mentioned above. Several users can be assigned to a planning position. Each user receives the error message in their own SAP-OFFICE-Inbox. As soon as a user enters and processes the error message, it disappears from the other inboxes.