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The ALE interfaces
The SAP Application Link Enabling (ALE) interface and ALE pass-through IDoc interface enable business process integration and asynchronous data communication between two or more SAP systems or between SAP and external systems. The data is exchanged in the form of Intermediate Documents (IDocs).
- For inbound processing, SAP pushes the data in IDocs to the SAP adapter. The adapter converts the IDocs to business objects and delivers them to the endpoint.
- For outbound processing, the SAP adapter converts the business object to an IDoc and delivers it to SAP.
To use the ALE interface or ALE pass-through IDoc interface for inbound processing, make sure that your SAP server is properly configured (for example, you must set up a partner profile and register an SAP RCF program ID to listen for events).
Application systems are loosely coupled in an ALE integrated system, and the data is exchanged asynchronously.
IDocs
Intermediate Documents (IDocs) are containers for exchanging data in a predefined (structured ASCII) format across system boundaries. The IDoc type indicates the SAP format that is to be used to transfer the data. An IDoc type can transfer several message types (the logical messages that correspond to different business processes). IDocs can be used for outbound and inbound processing. The SAP adapter supports the basic and extension type of IDocs.
For example, if an application developer wants to be notified when a sales order is created on the SAP server, the developer runs the Adapter Connection wizard to discover the ORDERS05 IDoc on the SAP server. The wizard then generates the business object definition for ORDERS05. The wizard also generates other resources, such as an EIS export component and Service Component Architecture (SCA) interfaces.
IDocs are exchanged for inbound and outbound events, and IDocs can be exchanged either as individual documents or in packets.
Transactional RFC processing
The adapter uses transactional RFC (tRFC) to assure delivery and to ensure that each IDoc is exchanged only once with SAP. The tRFC component stores the called RFC function in the database of the SAP system with a unique transaction identifier (TID). The TID is a field in your message.
- If the message flow does not send an SAP transaction ID with the business object, the adapter returns one after running the transaction.
- If the message flow has an SAP transaction ID, it must populate the SAP transaction ID property in the business object with that value before running the transaction.
The SAP transaction ID can be used for cross-referencing with a global unique ID that is created for an outbound event. You can create the global unique ID for managing integration scenarios.
Queued RFC processing
The adapter uses qRFC (queued transactional RFC) to ensure that IDocs are delivered in sequence to a queue on the SAP server or are received in sequence from the SAP server. Additional threads can increase the throughput of a message flow but you should consider the potential effect on message order. To maintain message order, ensure that your message flow is single threaded.