The main use of SOA from what I have experienced is in Reusability of services and promoting business agility by connecting disparate systems. Is there other major importance. If yes, please state them? I am looking for an answer which can make a novice understand what is SOA when you explain about its importance to him.
SOA is an architectural style, may be realized by web services, but SOA is not just about web services. Web services are all about exposing the implementation in a standard way, whereas SOA is concerned about integration. It basically aligns your IT infrastructure towards the changing trends in the business. Let us look at a simple scenario: Let's say there is the company that has its IT infrastructure first developed in the late 80s and was completely running on the mainframe. IT dept had many alternatives to the mainframe, but since they are of different technologies, they follow different protocols, and so communication cannot happen directly. They need some sort of layer in between that acts as a translator. So, the IT department had to write the intercommunication layers to talk to legacy code, Everything went on well until a point when the competition in the business grew so much as of now where the same system is interacting with MDM, dot net, infra services etc. All those cross-technology interactions had become too much to IT dept, both to develop and maintain. So, SOA is like a set of standards that have to be followed while building the business application which enables applications to be cost-extendable, flexible and makes the overall application cost-effective.