SAP PI provides a variety of adapters to make the integration of different applications possible, independent of their technical or application-specific protocols. Before the transmission to an external system, such an adapter ensures the possible conversion in an, for the other system, readable format. To process a message, the runtime engine first converts every incoming message in an internal message-format. A message is the data packet, which has to be transmitted.

The conversion through the runtime engine happens with the help of an adapter at the inbound side. To implement the transmission to another system, all data packages have to be converted in the format of the target system, in consideration of the relevant system parameters. This takes place before the outgoing transport and happens with a relevant adapter at the outbound side.

Process components exchange the data with different structure. For a trouble-free process this data has to be adjusted. The mapping shows, which conversion rules apply for the transformation of the source to the target elements. This mapping specifies which connection the structure notes in the source and in the target system have with each other. Every structure node in the source system is associated to a structure node in the target system.