Since SAP release 3.0, the data exchange between individual and distributed SAP systems and non-SAP systems is enabled via the Application Link Enabling (ALE) technology. The standard ALE business processes can be supplemented by own scenarios.

Two programming models are supported by SAP, which differ by the type of message sent.

• Distribution via BAPIs. This process is supported as of R/3 release 4.0A and is the basis for future developments.

• Distribution via message types. This programming model underlies the ALE developments of the R/3 release 3.x. The data transmission is asynchronous.

For SAP ALE, currently only distribution via message types are supported. This means that IDocs are received and sent asynchronously via the SAP ALE interface of an SAP system.