Data Exchange via IDoc with ALE or EDI

IDoc or Intermediate Document is a standard SAP document exchange format. IDocs allow different application systems to be linked via a message-based interface. The IDoc interface consists of the definition of a data structure (where the data structure is the IDoc) and a processing logic for this data structure. There are three main aims behind the use of IDocs:

• The structured exchange of business documents so that they can be processed automatically.
• The various degrees of structural complexity as displayed by different application systems can be reduced to a structure which is as simple as possible.
  Example: The structure of an SAP application document and the structure of the corresponding EDI message under the UN/EDIFACT standard.
• IDocs allow for extensive exception handling before the data is posted to the application.
  

The following techniques use the IDoc interface to exchange business data between different systems:

• Electronic Data Interchange (EDI) was the first form of data transfer to use IDocs. In EDI application scenarios, the processes, by definition, involve two partners: The sender and the recipient of an EDI message. EDI is a bilateral, document-oriented form of data transfer.
• Application Link Enabling (ALE) enables integration of business processes that are developed across several SAP systems or non-SAP systems. Thus, ALE is oriented to connect different applications on different systems. System-wide ALE message flows are modeled in a so called 'distribution model'.
  A typical scenario is the system data administration, where material master records have to be distributed from one central to several satellite systems. Nowadays, pure EDI scenarios are more and more executed on the basis of ALE technology, only that the system connection is 'just' bilateral.