What´s in a Name? Distinguishing between SaaS and SOA

Considerable confusion arises in distinguishing between software as a service (SaaS) and service-oriented architecture (SOA). Zachman´s framework can help to try to make sense of the alphabet soup of Web services and utilities that form the basis for both SOA and SaaS. The difference between SaaS and SOA is that the former is a software-delivery model whereas the latter is a software-construction model. A better way to illuminate the differences between these two concepts is to use the well-known Zachman architectural model. In this article, we briefly examine the concepts of SaaS and SOA, followed by a brief history of software architectural models. We use the Zachman model to differentiate the two architectural approaches to building software. Because the Zachman model is so intuitive, the approach we take to describe the differences between SaaS and SOA works well even with non-IT professionals.