Designing Mappings in SAP XI

Purpose

In SAP Exchange Infrastructure, interface descriptions of function calls (interfaces) are saved in XML format. The parameters of these interfaces determine the contents of the messages that are exchanged between systems (see also: Interface-Based Message Processing).

A mapping refers to the mapping of interfaces or messages to other interfaces or messages. You may need to use mappings of this type in a cross-system business process for a variety of reasons:

· A business partner expects other technical field names or another structure for transferring data.

· For technical reasons. For example, an RFC receiver adapter connected to SAP Exchange Infrastructure expects to receive messages from the Integration Engine in the format that it can understand, namely RFC XML. It then creates an RFC call in a system assigned to it. If the Integration Engine receives a message from a client proxy (BC-XI), the corresponding message must be mapped to RFC XML using a mapping so that the receiver adapter can process it.

You can define one or more mappings for an interface pair at design time, and save them in the Integration Repository. At configuration time, you can then select the mapping that corresponds to a specified business scenario. The Integration Engine transforms the message at runtime, in accordance with the saved mappings. Ideally, no mapping is required. In other words, the sender and receiver interface parameters are identical.

Implementation Considerations

Mapping is an essential part of SAP Exchange Infrastructure. At design time mappings can be saved in the Integration Repository and then selected for a business process at configuration time (see: Defining Interface Determinations). The Integration Engine executes the mappings saved in the Integration Directory at runtime, following receiver identification. If no mapping is required for a connection then the Integration Engine skips the mapping step.

Features

SAP Exchange Infrastructure differentiates between the following at runtime:

· Mapping Programs: Used to implement the mapping.

· Interface Mappings: Used to register mapping programs for an interface pair. You can also enter multiple mapping programs that are executed in succession.

Mapping Programs

The Integration Builder supports the following:

· The development of message mappings using a graphical editor integrated in the Integration Builder. Java classes are generated for use at runtime from a graphical description. You also have the option of enhancing the standard functions with user-defined functions.

· The import of XSLT or Java mapping as an archive. If, for example, XSLT mappings already exist or are to be developed using third-party tools, you can use the import function to import such mapping programs into SAP Exchange Infrastructure.

These mapping programs are executed on the J2EE Engine of SAP Web AS. SAP does not ship any mapping programs that run on the ABAP Engine. However, customers can develop such mapping programs by using the ABAP Workbench, see Mapping Development with the ABAP Workbench.

Imported archives

Type	Use
XSLT (eXtensible Stylesheet Language Transformations)	You use XSLT to convert an XML document to another document. This is achieved by using XSLT commands to search for tags in the source document and replacing them with other tags or values in the target document. It is also possible to switch to a Java program from XSLT.
Java Program	The message is transferred to a Java program as an inbound stream and can be imported using any parser (for example, SAX or DOM). The modified message is then transferred to an outbound stream. A Java program can also be a help program that in turn is used in another Java program or self-defined functions of a message mapping.