Proxy Generation (SAP Library - SAP Exchange Infrastructure (BC-XI))

Proxy Generation

Purpose

Using proxy generation, you can generate executable components for interfaces that you have created on the interface maintenance screen in the Integration Repository. You generate a proxy from a platform-independent description of an interface in the Integration Repository. This proxy enables systems to communicate with each other using the SAP Exchange Infrastructure. There are two types of interface objects in the Integration Repository:

Interfaces from existing components that you can import into the Integration Repository (for example, RFC function modules). An adapter enables the Integration Engine to convert calls from these interfaces into XML format; this format can then be understood by the Integration Server.

Interfaces that you create in the Integration Repository are platform-independent. To use an interface, you must first generate a proxy for a component.

The first approach is referred to as inside-out development, because interfaces that already exist in the system are called externally. The second approach is referred to as outside-in development, because interfaces can first be drafted independently of a component and then be implemented in a system landscape later. The outside-in approach is detailed below.

Integration

Proxy generation fetches information about an interface into the Integration Repository using HTTP, and converts it into a proxy object. The format in which the interfaces are read corresponds to the WSDL (Web Service Description Language) standard. In WSDL, data that is transferred using messages is described using XSD (XML Schema Definition Language).

Features

Outbound and Inbound

There are two kinds of interfaces: Outbound and Inbound Interfaces (also see: Properties of Message Interfaces). You must generate two types of proxies correspondingly:

For an outbound interface you generate an outbound proxy. This is a class with a method in the respective target language (see below). The application calls this method to send a message to a receiver.
For an inbound interface you generate an inbound proxy. This is not a class as in the outbound case, but a (Java or ABAP object) interface that the application must implement to be able to process an inbound message.

The generated proxies encapsulate the conversion of a method call in an XML message (outbound case), or the parsing of such a message and the call of the implementing class (inbound case).

Target Languages

You can generate proxies for the following languages:

ABAP Proxies
(only possible for SAP systems that have installed the SAP Exchange Infrastructure add-on)
Java proxies for J2EE applications on the SAP Web AS and for standalone applications

Example

The following graphic is a simplified illustration of how to generate and use proxies. The starting point is an outbound interface and a corresponding inbound interface in the Integration Repository. To implement this interface at runtime, the application generates corresponding proxies for each platform. (Also see: Interface-Based Message Processing).

Note

You can, of course, also generate inbound proxies for Java and outbound proxies for ABAP.

This graphic is explained in the accompanying text

The generation of proxies represents the transition from the design phase to runtime. The graphic outlines how a message is sent from a Java application to the Integration Engine, using an outbound proxy. There it is assigned to a logical receiver business system as per the settings in logical routing. It can then be assigned to a receiver interface and a mapping using a mapping relation. Furthermore, an end point determines the technical receiver of the message (technical routing). Finally, the Integration Engine forwards the message to a runtime component at the receiver, which forwards it to an ABAP application using a inbound proxy that complements the outbound proxy (also see: Runtime).

The graphic only shows one direction of communication, which is the case with synchronous communication, for example. The interfaces in the Integration Repository have corresponding attributes that indicate whether they are synchronous or asynchronous interfaces.