Determining ROI, in fact, is the greatest challenge developers working on SOA implementations say they face, according to a recent survey by Evans Data, which polled 368 developers working with SOA and Web services in September and October. So great is the challenge, according to participants, that it tops identifying available Web services, testing and validation, and paying for the technology.

So selling an SOA project to the customer takes some work.

“It’s a long-term initiative, it’s not a short-term quick hit,” says Evans Data CEO John Andrews. “It’s hard to understand, and it’s hard to describe.”

With that in mind, it doesn’t take much to understand why the adoption of SOA is in decline. A survey by Gartner found that the number of enterprises planning SOA adoption this year dropped by more than half, to 25 percent from 53 percent in 2007. The number of companies with no plans to adopt SOA jumped to 16 percent from 7 percent.

But all is not lost, says Andrews. It is still possible to make a convincing case for SOA, so long as the focus is on value and business gains rather than simply cutting costs.

And Saru Seshadri, president of Ultramatics, a solution provider in Oldsmar, Fla., says if there ever was a time to persuade customers that SOA makes sense, it is now that the economy has slumped and businesses are looking to do more with less.

“The need now is much more pronounced than ever,” he says.

To understand how it’s possible to achieve more with less through SOA, let’s see if we can shed some light on what SOA is.

Let’s start with the service part: A service, in this context, is a software function designed for a specific business need. With Service Oriented Architecture, the same service is reusable elsewhere in the business without an unnecessary duplication of processes. In developer lingo, allowing the service to function autonomously of the process but still using the process is called “loose coupling.”

To illustrate this, Seshadri uses an example in which a bank checks the credit rating of a loan applicant. Through the approval process, a credit check may take place at different points in the process. Often, the credit check uses a different set of criteria and is done differently depending on the stage of the process, creating an imperfect duplication that ties up staff and system resources.

Automation through SOA, Seshadri says, streamlines the process by eliminating the unnecessary steps and making the “service” – the credit check, in this case – repeatable.

Illustrating these types of improvements, says Seshadri, is a meaningful way to make the SOA case to the customer.

Through an evaluation of a customer’s systems, Ultramatics looks at the sum of the business processes, then figuring out which projects the customer needs but is unable to undertake because of the resources that its inefficient processes ties up.

The solution provider then assesses how that affects the way a business delivers services to its customers. Seshadri says the customer receives before-and-after scenarios that help turn an SOA project’s proposed outcome from abstract to tangible.

In doing so, Seshadri says Ultramatics addresses two important metrics – IT cost savings and revenue simplification. If the processes are straightforward and unnecessary duplication is eliminated, Seshadri says, the “order-to-cash” process for a business improves, which ultimately may have a positive impact on the bottom line.

“We don’t see SOA as a technology issue at all,” says Seshadri. “It’s a business challenge first.”

Andrews says because SOA is so intrinsically tied to business processes, as opposed to an IT-centric discussion, solution providers trying to sell SOA must make their case to the non-IT executives, such as CEOs, COOs and CFOs.

Adopting SOA is part of a strategy, not simply a solution for a specific IT problem, and as such, it’s necessary to open the eyes of the executives in charge of company strategy to the possibilities the technology opens up. Providers must make the case effectively that SOA makes the applications within the IT environment more adaptable and agile, he says.

“SOA is all about reuse and consolidating systems across the system,” Andrews says.

Once businesses buy into the SOA concept and agree to an implementation, Seshadri says it’s important to avoid complacency. Because of the long-term nature of the projects, communication with the customer is critical.

“The key is to go back constantly and give feedback,” he says.