The 2009 "SOA is Dead" meme may have turned out to be a tempest in a teapot, but there's no question that interest in Service-Oriented Architecture (SOA) waned in the 2010-2011 timeframe. However, today interest in, and deployments of SOA are resurgent. The conventional wisdom was that SOA was too difficult, suffering under a combination of intractable governance challenges and limited standards maturity. What happened?
The buzz in the blogosphere is that Cloud Computing is driving new interest in SOA. It's true that services play an important role in Cloud, as programmatic interaction with IaaS resources leverages loosely-coupled services (more often REST-based than Web Services), and SaaS apps also typically have REST and Web Services interfaces. (Services also play an important role in PaaS as well, of course, but the PaaS market is still all over the place.) But there's more to the story.
Furthermore, governance challenges are rapidly becoming the limiting factor for Cloud in companies in regulated industries as well as government agencies, and they're turning to their SOA architects for help. Those organizations who have had success with SOA governance, not just the technical nuts and bolts, but more importantly the organizational practices, are finding Cloud governance to be a natural extension of the work they've done governing their SOA initiatives. So, is Cloud governance driving the resurgence of SOA?
In fact, there's an even more significant reason why SOA is on the upswing: the vendors aren't pushing it any more. During SOA's heyday in 2005-2008, all you heard from the big infrastructure vendors was SOA, SOA, SOA. And according to them, how did you do SOA? By buying a bunch of gear from them, of course! The problem was, buying software before doing the planning and design part of the architecture was putting the cart before the horse, and many supposed SOA initiatives crashed and burned as a result.
Today, those same vendors are still selling all their SOA gear, of course, but the noise they're making is all Cloud, Cloud, Cloud. As a result, IT shops have less pressure on them to buy software in order to do architecture. The end result is a better focus on the role and importance of architecture -- and that's what's leading to the resurgence in SOA.
The downside of this trend, of course, is that the vendors are misleading their customers about how best to do Cloud. Cloud Computing, of course, means renting IT resources instead of buying them, and only using as much of them as you need when you need them -- two messages that are anathema to vendors. We've seen this movie before. So, while we approach the inevitable "Cloud is dead" moment, at least we can say that SOA is very much alive.