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And this is the Ali's vision about the layers in a SOA typical architecture (and believe me it is valid today!):
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A good article about the basic SOA principles and components definition.
/pub/blog/davisilva is a blog that aims to be the central repository of my ideas about SOA (service-oriented architecture), Software Engineering and its trends; a place where I can share interesting articles and useful links. All opinions are mine and do not represent the ideas the company I work.