ALE stands for Application Link Enabling. ALE in SAP is used for exchanging business data between different systems. This form of communication requires IDOC interface. The IDoc interface is made up of the definition of a data structure and the processing logic of this data structure. The data structure is the IDoc.
The IDoc is the general exchange format of the communicating systems. ALE supports the configuration and operation of distributed applications. It allows the controlled exchange of business messages between distributed applications with consistent data retention. The coupling between the distributed systems can be either narrow or loose. The application integration is not achieved through a centralized database. Instead, the applications access a local database. Data retention is redundant. ALE ensures the distribution and synchronization of master, control, and transaction data through asynchronous communications. ALE uses synchronous connections to read data.