ALE has three prime entities,
which participate in the message exchange process:
- SAP R/3 system
- ALE converter (inclusive of its sub-components)
- External non SAP R/3 system
The following diagram describes
how these three work together in an ALE scenario.
Figure 2: ALE FUNCTIONALITY
Image Source:
http://help.sap.com
2.1 Concept of Logical
Systems (LS):
Logical Systems represent R/3 or
external systems in the SAP R/3 environment for the distribution of
data. The existence of LS is mandatory for the corresponding R/3
client (which uses ALE or EDI). This LS acts as the "sender" for
outbound messages and a "receiver" for inbound messages.
In addition to the base LS,
another LS must be present within that R/3 system for each R/3 or
external system used for ALE interfaces. In an inbound ALE
interface, second LS represent the sender (another R/3 or external
system) with respect to the base LS (receiver). In an outbound ALE
interface, this second LS is the receiver on behalf of the R/3 or
external system with respect to the base LS (sender).
2.2 Message Type:
Message types (required for
sending the data across participating systems) relate to the
structure of the data called an IDOC (Intermediate Document).
Message types provide the format of the data, which can be exchanged
between SAP and non-SAP systems. ALE supports over 200 message types
in R/3.
