That’s because SOA demands a bigger investment and a longer strategic commitment than CIOs may think. The tactical part—service-oriented development—is a surmountable technical challenge. But the strategic part—creating an architecture based on a portfolio of services—asks that CIOs make a compelling case for enterprise architecture, a centralized development methodology and a centralized staff of project managers, architects and developers. It also requires a willing CEO and executive staff to pave the way for IT to dive in to the core business processes of the company. Understanding those processes and getting buy-in on enterprise sharing are the real sine qua nons of SOA-based business transformation.

For companies without technology products, big budgets or business leaders who chant the CIO’s name every time he comes into the room, SOA is neither a guaranteed path to business transformation nor, in some cases, even desirable. For smaller companies, for companies that have made big bets on integrated application suites and for companies that already have solid application integration strategies in place, SOA isn’t a "when," it’s an "if." CIOs need to pursue an SOA strategy carefully because the service development and architecture planning pieces of SOA are distinct but not independent—they need to be considered and executed in parallel. Services built in isolation, without taking into account the architectural and business goals of the company, may have little potential for reuse (one of SOA’s most important benefits) or may fail outright. Grand architectural planning exercises may drag on endlessly, without providing any real business benefit.

And that dot on the horizon, agility, is difficult to quantify. "We can’t say, Do SOA because it will give you a much more flexible set of systems," says Daniel Sholler, Gartner’s vice president of research. "There’s no metric that says if I’m more agile I will save X percent. The number-one difficulty with SOA is that it’s hard to get the ROI down to the spreadsheet level." Indeed, a survey by integration software maker WebMethods found that the top two inhibitors to SOA were, respectively, a lack of general knowledge and the difficulty of quantifying its ROI.

Indeed, there’s no inherent ROI in any technology strategy, cautions David Johns, senior vice president, CIO and chief supply chain officer for Owens Corning, a building materials manufacturer. Therefore, he says, "Developing a service-oriented architecture is not our goal. Driving productivity and driving waste out of the supply chain are the goals, and we’ll look at technology solutions from that aspect rather than what the industry may say is the latest, greatest thing."