What's the difference between an 'SOA' and 'enterprise' architect'?

What exactly is an 'SOA architect'? Is it any different from an 'enterprise architect'?

Those are the questions taken up at the most recently published SOA BriefingsDirect podcast, led by ZDNet colleague Dana Gardner. Steve Nunn, vice president and COO of The Open Group, joined John Bell, an enterprise architect at Marriott International, as well as the rest of the Gardner Gang.

As Dana put it, SOA expertise is hard to find. Bringing SOA to life, he observed, "is a lot like delivering a baby — it requires a copious nurturing, understanding, labor, and ultimately … pushing. So far, the job openings for SOA midwives outstrip the available pool of talent." The pay is good, and provides an opportunity to work at the highest levels of the business -- yet, we're starving for talent.

Marriott's John Bell describes the role of enterprise architect more as a city planner, one who oversees how the entire landscape comes together. "When they’re looking at the entire city, they're looking at how the various neighborhoods, how the various business zones, etc., fit into that city." The SOA architect, on the other hand, is focused on delivery of city services and facilitating communication within the city.

"My view is that the enterprise architect is at the top of the hierarchy, and at some place, working with the enterprise architect is an SOA architect, and their focus is on, "What are the services that are being delivered, how am I delivering them? What’s the infrastructure I am using to deliver it? Do I need – using that town model -- a police station? Do I need a fire station? Do I need a school? Do I need a museum? And, if I do, how do I get that service out to the community or to the entire city, not just an individual neighborhood?"

However, Jim Koblieus and Niel Macehiter saw the SOA architect's role as more expansive than facilitating communications. "The challenge that many SOA architects face is more around understanding what the services are that need to be delivered in a business-meaningful way, not just about communication and plumbing. It’s also about understanding the high-level, business-meaningful services," Niel observed.

Niel also said he finds that trying to make a distinction between SOA and enterprise architects is difficult:

"There is a business strategy, there are business processes and priorities, and there are the services we need at a business level. Then, there's a handoff to what’s currently defined as the SOA architect, who will actually define how those services are deployed in technology terms. So, the distinction is quite blurred. A service-oriented approach is one of the methodologies and the approaches that you can utilize to deliver or to support an enterprise architecture initiative."

Jim said if there is a distinction, he'll put "enterprise architecture at that very top layer, concerned with the end-to-end set of resources." that is followed by the SOA architect at the middle layer of development and reuse. At the layer below that, the IT or infrastructure architect handles components such as ESBs.