Duet Enterprise interoperability versus native WCF service integration

Recently I was at SAP Walldorf exchanging Duet Enterprise experiences with other partners and customers. One of the Microsoft solution architects present of a Finnish IT-consultancy raised the question when you should utilize Duet Enterprise above the plain usage of Microsoft WCF. This same question has (and is from time to time again) also been asked by the Microsoft architects of the organization where I’m involved in 2 SAP / SharePoint integration projects; both utilizing Duet Enterprise.

The question boils down to understand where is the return of investments. When does it make sense to investigate in purchasing and learning Duet Enterprise, instead of connecting via webservices to earlier build custom connectivity? And to be honest, from a Microsoft developer’s perspective the latter is more appealing, because technically more challenging and also familiair approach plus technology.

The valid answer of Holger Bruchelt on this question was that it strongly depends on the size of your SAP / SharePoint interoperability case. If just for a single application context, with no more scenarios in sight on a medium term, it is very hard to make the business case for purchasing, training and implementing Duet Enterprise. Most likely you can better make a dedicated 1-on-1 integration via the known way of Microsoft WCF, and connect direct to SAP webservices (BAPI webservices, or Enterprise Services).
However, when SAP / SharePoint is a strategic issue for the organization; with multiple applications of it on the horizon; Duet Enterprise is a very valid option to consider. The execution of multiple projects makes it profitable to invest the license and implementation costs for the added value of Duet Enterprise as standards-based SAP/SharePoint interoperability foundation.

A derived question is how Duet Enterprise interoperability compares against native service integration. This question is more complex to answer.
Duet Enterprise is (a consumer of) Service Integration. On SharePoint side it relies on the strengths of SharePoint Business Connectivity Services (BCS) to interoperate with the SAP landscape. BCS supports different connectivity-models to external systems and data repositories, including via webservices / = Service Integration. Duet Enterprise is an example of this: it invokes SAP NetWeaver Gateway webservices through means of BCS. For SharePoint developers, BCS can thus be seen as an abstraction of the Service Integration layer. On top of this abstraction, the SharePoint platform includes diverse BCS capabilities to aid the developer in composing the interaction with external systems: External List, Business Data webparts. In addition, the BCS API can be programmed for custom construction.

There are noticable differences between native service orientation and service integration using Duet Enterprise:

• Duet Enterprise enables the entire system chain from provider (SAP Business Suite) to consumer (Microsoft SharePoint); on design time and on runtime moments. At design time, Duet Enterprise can be a significant accelerator to expose SAP data into SharePoint context. This is achieved through the Duet Enterprise design tools that are integrated in both SAP and Microsoft landscape. And by using SharePoint BCS as connectivity layer, the step to develop and provision a separate middleware layer is excluded. For the runtime handling, Duet Enterprise provides out-of-the-box capabilities for interoperability aspects: data retrieval, display and management, Single Sign-On, autorisations, end-to-end monitoring.
• Duet Enterprise is a standard SAP / SharePoint interoperability foundation, designed and maintained by SAP and Microsoft together. The 2 software vendors execute a clear roadmap to further develop their shared product. In this roadmap, the product is aligned with the new developments in SharePoint and in SAP technology landscapes. Further, via the Unite program, the Duet Enterprise ecosystem expands on the basic deliverable with additional content packages. The expectation is that the ecosystem will steadily grow, and also deliver technical and functional components that end-organizations can deploy for custom composition and build of company-specific scenario’s.
• Duet Enterprise lifts on SAP NetWeaver Gateway; Gateway is now a central component in the SAP architecture to expose SAP data and processes to external clients: SharePoint [via Duet Enterprise], but also (and with more emphasis real soon) to Mobile [via Sybase Unwired Platform]. Relying on Gateway enables organizations to expose SAP data + processes to multiple channels, with reuse of the same Gateway services [thus reduce on development and maintenance effort + costs].