Processing XML Messages 
Purpose
The Exchange Infrastructure is based on the sending of XML messages between individual application components. The processing of XML messages of this type is therefore an essential part of this infrastructure. The infrastructure is based on information located in a central repository and directory that is called at runtime. The runtime environment required to process this information is known as the Integration Engine.
Prerequisites
To be able to process XML messages successfully, you must first have set up the entire integration environment and configured the runtime environment correspondingly.
You also require the role SAP_XI_APPL_SERV_USER to be authorized to process XML messages. The authorizations contained within this role are required both by the user who is logged on, who calls the Integration Server using an application, and the user under which message processing takes place on the Integration Server.
Process Flow
When the Integration Engine receives an XML message, it processes it using its pipeline; this pipeline mainly comprises the following processing steps:
· Inbound processing with receiver and interface identification (logical routing), technical routing, and message branching
· Outbound processing with mapping and the receiver call
Routing refers to the receiver or receivers of an XML message that must be localized within the existing system landscape.
Logical routing uses routing relations to determine the name of the receiver and the receiver interface, while technical routing in the Integration Directory queries the end point (the physical address) required to call this interface.
Mapping means the mapping of values and structures of the sender application to the corresponding values and structures of the receiver application.
For more information about message processing, see Configuration Time.
The following aspects must also be considered when processing XML messages using the Integration Engine:
· Processing of Acknowledgment Messages
