The ALE interfaces

The SAP ALE interface enables business process integration and asynchronous data communication between two or more SAP systems or between SAP and external systems. The data is exchanged in the form of Intermediate Documents (IDocs).

The adapter supports outbound and inbound processing by enabling the exchange of data in the form of business objects.

For inbound processing, SAP pushes the data in IDocs to the SAP adapter. The adapter converts the IDocs to business objects and delivers them to the endpoint.
For outbound processing, the SAP adapter converts the business object to an IDoc and delivers it to SAP.

To use the ALE interface for inbound processing, you must make sure that your SAP server is properly configured (for example, you must set up a partner profile and register a program ID to listen for events).

Application systems are loosely coupled in an ALE integrated system, and the data is exchanged asynchronously.

IDocs

IDocs are containers for exchanging data in a predefined (structured ASCII) format across system boundaries. The IDoc type indicates the SAP format that is to be used to transfer the data. An IDoc type can transfer several message types (the logical messages that correspond to different business processes). IDocs are used for outbound and inbound processing. The SAP adapter supports the basic and extension type of IDocs.

For example, if an application developer wants to be notified when a sales order is created on the SAP server, the developer runs the external service wizard to discover the ORDERS05 IDoc on the SAP server. The wizard then generates the business object definition for ORDERS05. The wizard also generates other artifacts such as an EIS export component and SCA interfaces. These artifacts are saved in an integration module. The application developer can then use this SAP inbound module to build the application.

IDocs are exchanged for inbound and outbound events, and IDocs can be exchanged either as individual documents or in packets.

For outbound processing, the adapter uses the IDoc business object to populate the appropriate RFC-enabled function call made to the SAP server.

For inbound processing, IDocs can be sent from the SAP server as parsed or unparsed documents

For parsed documents, the adapter parses the IDoc and creates a business object that reflects the internal structure of the IDoc.
For unparsed IDocs, the adapter processes the IDoc but does not convert the data portion of the IDoc.

Transactional RFC processing

The adapter uses tRFC (transactional RFC) to guarantee delivery and to ensure that each IDoc is exchanged only once with SAP. The tRFC component stores the called RFC function in the database of the SAP system along with a unique transaction identifier (TID).

The most common reason for using transaction ID support is to ensure once and only once delivery of data. To make sure of this feature, select the transaction RAR file (CWYAP_SAPAdapter_Tx.rar) when you configure the adapter.

Note: The SAP transaction ID property is always generated by the external service wizard; however, it is supported only for outbound operations when the CWYAP_SAPAdapter_Tx.rar version of the adapter is used.

The client application must determine how to store the SAP transaction ID and how to relate the SAP transaction ID to the data being sent to the adapter. When the events are successful, the client application should not resubmit the event associated with this TID again to prevent the processing of duplicate events.

If the client application does not send an SAP transaction ID with the business object, the adapter returns one after executing the transaction.
If the client application has an SAP transaction ID, it needs to populate the SAP transaction ID property with that value before executing the transaction.

The SAP transaction ID can be used for cross-referencing with a global unique ID that is created for an outbound event. The global unique ID is something you can create for managing integration scenarios.

Queued RFC processing

The adapter uses qRFC (queued transactional RFC) to ensure that IDocs are delivered in sequence to a queue on the SAP server or are received in sequence from the SAP server.