SAP Integration Using IDocs

BizTalk Server 2000 can be combined with the BizTalk Adapter for SAP to provide a solution based on using IDocs for integration with SAP R/3. There are several reasons why this approach may not be appropriate for the problem being discussed in this chapter. In the proposed scenario, the information flow is primarily from the user and the Web middleware layer into the SAP system. The predominant direction of these flows has an impact on the applicability of the BizTalk Adapter for SAP to the proposed scenario.

The current version of the SAP R/3 suite implements approximately 700 IDoc types that can be used by external applications for integration. If an IDoc does not exist for transferring the SAP information required in a specific EAI scenario, then using IDocs and the BizTalk Adapter for SAP is not a possibility. Since the IDocs provided with SAP R/3 cover only a subset of the full SAP R/3 suite, there will be some cases where integration using IDocs is not feasible.

The BizTalk Adapter for SAP uses RFC methods to connect to the SAP Business Object Repository and read the schema of all defined IDoc types. Based on knowledge of the IDoc formats, the BizTalk Adapter for SAP can use other RFC methods to request a specific IDoc from the SAP system. The IDoc returned from the RFC call is parsed knowing the structure of the IDoc format and the information is formatted as XML and passed to BizTalk Server for delivery to the requesting application.

In contrast, when the BizTalk Adapter for SAP is requested to send an IDoc, it expects to be handed a document formatted like an IDoc in XML. So in order to use the BizTalk Adapter for SAP in the scenario discussed in this chapter, the Web middleware layer would require a thorough understanding of the format of any IDocs to be used to write information to the SAP system. The Web middleware layer would need this information in order to format the equivalent IDoc for sending to the SAP system. Given the complexity of the IDoc format, this conversion is a complex task. While the conversion would be possible, the programming effort required is likely to be very substantial. To create a generalized solution that could interrogate the SAP repository for information on the IDoc format, the Web middleware layer would essentially be replicating the work accomplished by the BizTalk Adapter for SAP.

A later chapter in the business-to-business (B2B) section describes a more appropriate scenario for using BizTalk Server integrated with a SAP system.

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