There's been no shortage of discussion about the transition between service-oriented architecture and cloud, particularly among vendors repositioning (or "cloud washing") their offerings for the next big thing. My friend Dave Linthicum is adamant that many of the same principles and methodologies invoked for SOA -- particularly effective governance -- need to be applied to emerging cloud formations. He also points out that while SOA is the foundation, cloud is the delivery mechanism for services.
Gartner analyst David Mitchell Smith, however, sees things somewhat differently, saying SOA and cloud address different levels of service delivery. Smith, speaking at Gartner's recent SOA and software summit in Sydney, was quoted in CIO as describing how SOA is more about the underlying technology, while cloud is about the business relationship:
“In the world of SOA we talk of services as software, live components and objects (technical things), but in the real world when you talk about service it is outcome based... People will say ‘we are doing SOA so we are ready for the cloud’, but the difference between SOA services and the cloud context is huge. With cloud, you pay for the outcome, not the technology. In cloud the service terminology you are focusing on is a relationship between service provider and consumer not technology provider and consumer.”
"There is a huge leap" in assuming SOA equals cloud. However, Smith adds that the concepts are related and undertaking SOA is a good thing to prepare for cloud. Still, he says, cloud is a "style of computing, not a technology or architecture."
Fair enough, and I don't think David Mitchell Smith and Dave Linthicum are too far apart on this point.
Still, people in the industry have spent years trying to hammer home the point that SOA is not about technology at all; it's about building an architecture that effectively provisions business services when and where needed across enterprises.
Another point in which I beg to differ is the nature of the relationship between service providers and service consumers. Smith says cloud differs from SOA in that it "is all about trust and if you don't trust the provider, you shouldn't be doing it.”
The success of SOA, too, is built upon trust between service providers and consumers -- even when they are part of the same enterprise. Without trust, there will be no service oriented architecture, let alone cloud.
UPDATE: Dave Linthicum weighed in -- as I hoped he would -- on Smith's remarks. His reaction:
"In order to be successful with cloud computing we can't lose sight that most successful cloud computing architectures are SOAs that leverage private, public, and hybrid cloud platforms. If you're considering leveraging cloud services without putting in the context of SOA, you'll crash and burn pretty quickly, trust me."