The first step in the path to the SOA is basically the expression of a very simple approach: identifying the business functions that your applications are made of. Let's analyze this phrase in detail:
Identifying: is the ability to find and isolate the software parts that provide self-contained and atomic functionalities. This implies designing in a modular way, that is divide ("et Impera", Romans would say) the logics of your problem into small and well defined call specifications. We need to build the boundaries of our software parts and contracts to use them, always keeping in mind that a part that is re-usable in many contexts is sort of a piece of gold. In a sense, we are simply leveraging the concept of "interface" to a more abstract level, the business rule's level.
Business functions: refers to the fact that with SOA we are focusing on the model-and-business layer (the M letter in MVC), and not the presentation side (the View and Controller).What we are talking about...