Andrew Oliver makes good points about the dependency of SOA strategy success on executive management support, the preference of IT departments for technology rather than strategy solutions, and the lack of cloud integration standards; but these do not logically support his argument for including SOA in a cloud strategy. At a high level I agree that SOA can bring a lot of value to cloud; where I differ is why and how.
As with SOA, if cloud concepts (of one-to-many, shared, standard services) are not applied to the business architecture, then adoption of cloud for IT enablement will not solve business integration problems – especially when the root causes are in the business processes rather than in the IT enabling those processes. (In the latter case, at best cloud – and SOA – integration solutions are expensive band-aids keeping the problems covered until the business heals itself, and at worst allow the problems to fester and deepen.)
I believe that for optimal results, cloud (and SOA) adoption needs to start with the development of a cloud adoption strategy at a corporate level (i.e. business-led development), closely followed by appropriate modifications to the corporate governance and executive compensation criteria. (Without such changes, the propensity is for LoB and IT executives to ignore the adoption strategy: the former buy SaaS and other types of outsourcing solutions which don’t integrate well with the rest of the business, and the latter build fancy platforms eschewed by the rest of the business.)
Basically, a company that has successfully adopted SOA should likewise be successful at addressing integration issues and adopting cloud for internal operations – not because they have SOA, but because they have worked out a successful adoption process.
As Amy Wohl and I stated in our presentation “Rainmaking: SOA Gets More Out of SaaS in the Cloud” at IMPACT 2009 (IBM’s premier SOA conference), SOA brings a lot more value to SaaS providers (cloud producers) than to cloud buyers (of solutions to enable internal operations). With SOA as part of the delivery stack, each subscriber perceives a unique configuration, but the application administrators perceive a common (single) configuration – a user can tailor “the” application to meet his particular business requirements without creating a one-off application configuration which would need to be separately (and expensively) managed.
In summary, if you already have SOA, then leverage your SOA adoption experiences and SOA integration facilitation in the development and execution of your cloud adoption strategy; but if not, then SOA adoption should only be a priority if your cloud strategy concerns producing and delivering SaaS products (or SaaS-enabled BPO services).