What's the difference between SOA and Web services?

Wow! All this talk of customer information and data quality and harmonization and I thought my readers were ignoring my admonishments to embrace service-oriented architectures as part of their MDM strategies. So thanks for noticing.

Think of a Web service as a conversation, and SOA as the telephone system. A Web service is a "call" to an application, a system, or a hub that asks a question, like: "Does this customer already exist?" By definition, a Web service uses the web to communicate its business question.

SOA, on the other hand, is the architectural framework that enables a series of those Web services to occur. You don't deploy "an SOA," rather you deliver these Web services using a SOA framework. Usually when someone talks about deploying SOA, they're really talking about breaking up their business processes into Web services. So now, instead of lots of different systems in your company asking the question, "Does this customer already exist?" to its native database, it can simply use a Web service to call a central location and ask the question. With MDM, the answer is always the same, because the data's been mastered; this is why the trend of "data as a service" really has legs. A while back Aberdeen reported that big companies expect to save as much as $53 billion between 2006 and 2010 by applying SOA. The challenge with SOA is that many IT executives have attention spans that last about as long as a Botox injection. SOA is big, multi-faceted, and incremental. And there are always residual wrinkles.