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The following section describes the specific functional characteristics of the different communication technologies in more detail. Application examples are used to demonstrate which technologies are particularly suitable for which implementation.

Synchronous and Asynchronous Communication

Communication between two systems can be basically split into two types: Synchronous and asynchronous communication. Both forms of communication have specific advantages and disadvantages, which can affect either the business application or the system administration.

Synchronous Communication

Synchronous communication uses a single function call. Prerequisite for this is that at the time the call is made (or the message is sent), the receiving system is also active, can accept the call and further process it if necessary. The report sending the call waits for the response of the receiving system:

  • Advantage: Synchronous communication can be implemented in function calls that require the immediate return of data to the sender system.

    Example: You create a purchase order with account assignment in the sender system, and you want to perform a budget check in central accounting before you save the purchase order.

  • Disadvantage: You need to ensure that both systems are active and can be contacted. If they are not, this can lead to serious disruption of processes. In particular, problems can arise if the receiving system is not available for long periods of time due to maintenance (for example, for a system upgrade).

Asynchronous Communication

For asynchronous communication, the receiving system does not necessarily have to be available at the time a function call is dispatched from the sender system.The receiving system can receive and process the call at a later time. If the receiving system is not available, the function call remains in the outbound queue of the sending system, from where the call is repeated at regular intervals until it can be processed by the receiving system:

  • Advantage: The receiving system does not have to be available at the time the function call is made. If the system is unavailable for a long period of time, for example, for an upgrade, it can still process the data that has been sent in the interim at a later time, and processes in the sending system remain unharmed.

    Example: You are sending a purchase order to a vendor system. The sending system cannot influence the availability of the receiving system. If the receiving system is not available, the purchase order can be sent repeatedly until the vendor system is available again.

  • Disadvantage: Processes that require an immediate response to the sender system cannot be executed using this method.


In asynchronous communication, you usually have the option to send data (for example, business documents or changes to master data) in packages or individually (immediately). Note that the Send Immediately option in asynchronous communication should not be confused with the method synchronous communication).

The advantage of sending data in packages is that system resources are employed more efficiently, because each function call occupies one work process in the system.

Example: You want to distribute 100 material master changes to other systems. If you send the changes in a package (with 100 pieces) you only require one work process. If you sent the same 100 material master changes individually, you would need 100 work processes in the system. When using asynchronous communication, you should therefore always carefully consider the availability of your system resources and the necessity of immediate data transfer.

More Information

Which communication technology is suitable for which purpose? For more information, see the following examples: