Data Flow: WMS Transfers Data (SAP Library

Data Flow: WMS Transfers Data

The data flow across the interface between the Warehouse Management system (WMS) and the external system (WMS-WCU interface) is explained using the example of the communication flow for transferring transfer order data from the WMS to the external system.

For further information on the business background, see Scenarios for Connecting External Systems.

Prerequisites

You have defined the necessary TCP/IP settings. For more information, see BC – SAP Communication: Configuration.

You have defined the ALE interface in the Customizing for Warehouse Management under Interfaces ® External Systems ® Configure Warehouse Management ® Warehouse Management View ® Activate Interface per Whse Number.

You have defined when a transfer order (TO) is relevant for transfer to the external system in the Customizing for Warehouse Management under Interfaces ® External Systems ® Configure Warehouse Management ® R/3 System -> External System ® Define Interface Control.

You can define that TO items are relevant for transfer to the external system:

For a storage type
For a WMS movement type
For a combination of storage type and WMS movement type

You define the external system, which receives the TO item.

Process Flow

During TO creation in the WMS, the system determines from the Customizing settings, that the TO or a TO item is relevant for transfer to the external system.

During TO creation, the system prepares the data to be transferred in the form of an IDoc.

NOTE

For further information on IDocs and their construction, see Description of the IDocs.

The system saves the IDoc in the database.

After creating the IDoc, the system triggers the transfer of the IDoc to the external system asynchronously.

The system can transfer individual IDocs or collect several IDocs and then transfer them to the external system later. The transfer is based on the Remote Function Call.

The external must be available with a corresponding program to receive the data transferred from the WMS.

For more information, see Basis ® Basis Services/Communication Interface ® Remote Communications ® The RFC API ® Programming with the RFC API.

The external system saves the IDoc data it receives and sends a delivery receipt back to the SAP system.

Recommendation

We recommend saving the data in the external system straight away to ensure that the transfer of the IDoc and processing of the transferred data occurs separately.

Status management for the data received should prevent the external system from processing the data twice.

The external system should be able to recognize IDocs that have been transferred by the SAP system before. This is made possible by the unique transaction identification number (transaction ID), which the SAP system assigns for each communication process. For more information, see Basis ® Basis Services/Communication Interface ® Remote Communications ® The RFC API ® Transactional RFC Client Programs.

Note

The external system can also recognize double transfers from the IDoc number. Note that an IDoc number is only unique within one client of an SAP system. If several clients of an SAP system or several SAP systems are involved in the communication with the external system, the IDoc number is no longer unique. In this case the external system cannot recognize IDocs that have been transferred twice from this number.

Error Processing

When you send an IDoc from the WMS to an external system, the following problems may occur:

Troubleshooting

Symptom	What You Should Know
Update termination in the SAP system during the application	An update termination during creation of a transfer order does not affect communication with the external system, because the system only creates an IDoc once the source SAP system document exists. The TO and the IDoc are creates in the same LUW, therefore they are updated synchronously.
Error in the ALE interface: Transferred data is syntactically incorrect	ALE adopts the IDoc and saves it, but cannot transfer the IDoc to the external system. For more information, see IDoc Error Processing.
Error in the ALE interface: The outbound partner profile for the receiving system The IDoc message type are not defined	For more information, see IDoc Error Processing.
There is no connection between the SAP system and the external system	The SAP system tries to set up the connection to the external system by running a report in the background at a later time. As soon as the connection between the two systems exists again, the SAP system automatically transfers all IDocs, which have not yet been sent. You can also start this report manually. For more information, see Processing Technical IDoc Errors.