Application Link Enabling (ALE)

Application Link Enabling is a means of creating and operating distributed applications. The basic concept of Application Link Enabling is to ensure operation of a distributed, yet integrated system landscape. This involves business-controlled message exchange using consistent data across loosely linked application systems. The applications are integrated through synchronous and asynchronous communication, not through a central database.

Systems that use ALE to exchange data can be located at the same company, or they may belong to different companies. One of the characteristics of ALE is that different systems are linked in business terms through secure and consistent data transfer.

You could also describe ALE as being composed of the elements: who exchanges
which data when, with whom, and by what means.

Implementing ALE therefore requires that you clarify the following points in detail:
1. Identify the business process and the objects involved
2. Identify the information to be transmitted
3. Specify the format for the data to be transferred
4. Decide on the transfer technology to be used
5. Decide on the transfer type
6. Specify the destination of the data transfer

The data is often identified within the SAP system using a business object and its Business Application Programming Interfaces (BAPIs). A BAPI is a method of a business object, for example, the material master record. A permissible method could be creating or changing the material master data. BAPIs normally enable you to edit all data belonging to the object.

The IDoc format describes the structure of .intermediate documents.. There are various kinds of IDoc formats for different types of data to be exchanged. Alternatively, you can use ALE to transfer data in an agreed XML format.

There are two basic transfer types: synchronous and asynchronous.

Synchronous transfer means that the data is transferred at the time of creation or change. You
can start asynchronous transfers at intervals of your choice.

There are very few restrictions on the systems that can be linked. The systems involved must have the technical capability to receive the communications (RFC-enabled, HTTP-enabled) and interpret the format transferred (IDoc, XML).
SAP systems of different releases can be linked using ALE.

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