The Duet Architecture Outlined

Despite seemingly simple processes that Duet enables, the product exemplifies how serious an undertaking a commercially available composite application can be. When the goals of Project Mendocino (now Duet) were first formulated, it reportedly[1] became clear that two very different architectures needed to be brought together. On the one side was the ubiquitous client application, which required local data storage, while on the other side was the proverbially complex SAP ERP environment. The different technologies in this case reportedly made it quite easy to select Web services as the interface technology, since both camps added standards-based Web services support in their last releases. However, in this case, simply connecting these two worlds using Web services did not offer a comprehensive enough solution. Namely, the goals required more extensibility, because SAP wanted to enable a model-driven environment on the client side, which would allow Duet to push additional screens and updates to the user without the need to continuously run through an installation and reinstallation whenever business needs changed.

On top of that, Microsoft Office currently works in online as well as offline modes. This capability had to be maintained in Duet as well, since users had to be able to trigger activities while being offline which would later have to be automatically resynchronized once their machines went back online. At the time, Microsoft and SAP also realized that the involved disparate system components (i.e., Microsoft Exchange Servers, Microsoft Office, and SAP ERP systems) are of such a high value to customers that massively updating those environments (and exposing the existing system landscape to any unnecessary disruption) would be unacceptable. SAP and Microsoft weighed these requirements carefully and realized that there was a the need for a communications hub that would sit in the middle of the two existing environments and "mediate" communication and processes. The hub collects various configurations from the back-end system, determines the objects that should be exposed, and decides which activities the user can trigger and how all of that ties together within the user screen. The communications hub is also referred to as the Duet Extensions, which are connected with the Microsoft Office client and the SAP ERP system. The result is that there are three primary parts to Duet's architecture: 1) the Duet Extensions; 2) the Microsoft Office Add-On; and 3) SAP ERP foundation.

More Than Meets the Eye

In addition to disseminating useful SAP data among knowledge workers (outside of its traditionally limited power-user dispatch list), Duet has been crucial for being a "proof of concept" model illustrating the potential development and adoption of composite applications, especially when the result of a joint collaboration between two software giants and market influencers.

Indeed, Duet is one of the first examples of a tangible SOA-based composite application product. While several tools use SOA conceptually, in ways that are sometimes hard to grasp, this tool is based on consuming services in concrete ways that benefits almost every information worker. Duet showed how SOA can be applied to the user experience through familiar desktop applications, and for some users, it will deliver functionality that supersedes the need to work directly with any line-of-business (functional department) or back-office enterprise applications. By exposing functionality and giving even the most casual users an easier way to update data that normally resides only in the back-office system, Duet embraced the innovative potential of SOA services. It exposes features from underlying ERP systems in new ways that create more value. And these services can be used together, even though they were probably written for a system that was designed before SOA was someone's figment of imagination.

This fulfills one of SAP's short-term goals for ESA (SAP's variant of the SOA blueprint) adoption—to create simple services (software components, if you will) that work on top of legacy applications already used by organizations. In the future, the entire stack which encompasses ERP, CRM, and all other SAP Business Suite solutions will eventually evolve to use business objects as their underlying application. Instead of having a rigid and unwieldy monolithic set of applications, SAP is creating a collection of business objects that can be applied in more flexible ways. By late 2007, there will be more services to choose from than the ones used to support Duet, since ESA follows the SOA format of "model once, run anywhere". Namely, instead of hard-coding multiple solutions that apply to different domains, ESA employs business objects or services that are modeled in a way that allows them to handle different solutions. Duet is just one of many client-side solutions that ESA will enable.

To understand how Duet is in tune with SOA, it is important to become familiar with the new stack defined by SAP ESA, and to understand what a composite application is. Webopedia defines a composite application as an application that consists of more than one type of service delivered from an SOA environment. It can range from functionality to entire applications. Services are generated through "local" application logic that controls how services interact with each other. For more information, see Understanding SOA, Web Services, BPM, and BPEL.

As a composite application, Duet overlaps with nearly every part of the new SOA stack:

• User screens. Duet uses the familiar Microsoft Office desktop interface, which is achieved not by hard-coding the UI, but through backend modeling and deploying it to the client.

• Process orchestration. Duet uses a communications hub referred to as the Duet Extensions to route data to and within the ERP system.

• Process integration. Using the aforementioned extensions, Duet translates data from Microsoft Office applications such as Excel into a format that is easily understood by existing ERP tools and their respective enterprise services.

• Process workflow. All of the usual workflow processes within SAP ERP take place within the context of Microsoft Office's desktop tools.

• Distributed data. The ability to cache data for working online or offline also plays an important part in the functionality.

Application Giants in Duel—and Duet—for Users' Hearts, Minds … and Wallets

The relationship between the two software powerhouses, Microsoft and SAP, has been intriguing to put it mildly, at least since Microsoft's entry into the enterprise applications arena in late 2000 (see Microsoft 'The Great' Poised to Conquer Mid-market, Once and Again ). While the relationship has been depicted by many through a myriad of antonyms, such as "on-off", "hot-cold", or "love-hate", currently, it can best be described as "mutually civil". One can even find some uncanny similarities between the two, such as the occasional involvement in intellectual property lawsuits (whether as plaintiffs or defendants) or through the relatively recent, almost coinciding departures of technological visionaries, Satya Nadella and Shai Agassi, respectively (although Nadella was merely transferred within Microsoft, to the search and ad group that will hope to fend off Google's undeniable threat).

Microsoft and SAP then entered a "strange bedfellows" or co-opetion phase in their relationship, by dallying in business applications. Acting like two high-profile on-again, off-again celebrities, the two were dismissive about questions from the press and analysts about the inevitable competition this partnership would create (i.e., responding "We do target different sizes of companies"). Nonetheless, this stance become moot owing to SAP's forays into small business via SAP Business One and Microsoft's propping up of Microsoft Dynamics AX, as an upper mid-market solution. Then came a perceived snub by SAP for opting for Java 2 Enterprise Edition (J2EE) as a primary development environment for its infrastructure and development platform (while there is, nonetheless, some lesser valuable interface options for the counterpart Microsoft .NET Framework environment). However, SAP's move was quite logical given the still lingering perception of Java's better fit for larger enterprises (see Understand J2EE and .NET Environments Before You Choose ).

Any hard feelings between SAP and Microsoft were short lived, as we found out in 2004 when the two were engaged in secret (and startling) merger talks, which was quickly put ad acta before the news broke (whether for good remains to be seen). For most of that year, both vendors had to spend time explaining their separate forays into developing next-generation, service oriented architecture (SOA)-enabled products. Then 2005 seemed to be the year of bliss, where the two expressed mutual respect, and even worked jointly on a commercially available product featuring best of both worlds. Specifically, SAP and Microsoft joined together to leverage the openness of the SAP NetWeaver and Enterprise Service Architecture (ESA) blueprint (see Multipurpose SAP NetWeaver ) with the .NET-based architecture of Microsoft Office desktop applications suite (see Subtle [or Not-so-subtle] Nuances of Microsoft .NET Enablement ). The result was the joint product code-named Project Mendocino (the name of a town halfway between the companies' respective US headquarters) that promised to deliver familiar Microsoft Office desktop management and productivity tools as the façade for the heavy-duty lifting processes of SAP's enterprise applications. In other words, Project Mendocino extended and automated selected business processes from SAP ERP (Enterprise Resource Planning) through the familiar Microsoft Office user interface (UI), by providing role-relevant displays of information while retaining SAP applications' process context and the necessary collaboration and analytic tools.