Synchronous communication is typically used in the following application scenarios:
Creating a sales order in a different system (central sales).
Performing an availability check for a particular material in response to an inquiry in the vendor system.
Performing a source determination for a material order in another system (central master data administration for business partners).
CRM / SRM
Performing an availability check for a material in the SAP backend system when using the components CRM or SRM (EBP).
Executing a budget check for your cost center in central accounting while creating a purchase order in the component SRM (EBP).
Requesting a list of all cost centers from a central accounting system.
Sending a call to your BW component (Business Information Warehouse) to request a particular evaluation.