In-Depth

ESB: A Building Block to SOA

• By Kathleen Ohlson
• October 1, 2005

The rise of enterprise service buses is due in part to the service-oriented architecture explosion. Businesses view SOA as a way to reuse software—even legacy apps—as services with loosely coupled interfaces.

An ESB helps enterprises connect legacy systems into a SOA network, but can’t—by itself— provide an entire SOA infrastructure. It acts as an integration platform, handling messaging, development, data transformation and processing for SOA.

“The ESB message is appealing to a lot of people out there,” says Anne Thomas Manes, an analyst at Burton Group. “It’s a silver bullet—you put the software in, hit a button and then presto!”

Experts say that belief is so far from the truth.

“There’s still a lot of confusion,” says Jason Bloomberg, an analyst at ZapThink. “Just because you install an ESB doesn’t mean you have SOA. Companies set [their SOAs] up as an EAI product, but they have tightly coupled interfaces like an EAI.”

SOA isn’t about ESB and other software; it’s about corporate culture and best practices, according to analysts and users. Business managers are reluctant “to take the extra time and money to build an application when [they see] no benefit coming to them immediately,” Manes says. “If they’re not going to be compensated, [they’re] not going to be interested” in building a service, she says. If these managers lack control over that service, that only increases the project’s risk.

Corporations must identify business problems, craft plans to solve them, determine if technology will solve these issues, and most importantly, be very flexible.

SOA needs to match a company’s business needs, “rather than be a big model of what SOA could be,” says Jayson Minard, CIO for Abebooks. The online book marketplace is building a SOA for its inventory system based on Sonic Software’s ESB and SonicMQ messaging system. He has a map of Abebooks’ SOA infrastructure on his office wall, but expects the setup to change. “There’s all of this global architecture, and I don’t know if we’re ever going to get there, but I know every month it’s going to change,” Minard says.

Analysts and users also suggest focusing SOA on specific business needs, rather than a Big Bang approach. Stratus Technologies implemented Cape Clear Software’s ESB to build a SOA around its order processing system.

“Don’t take too big of a bite to start with,” says Cecilia LeBlanc, Stratus’ applications/IS manager. “It went successful for us because we focused on a particular business operation,” resulting in quicker wins that help Stratus with other SOA implementations.

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