Processes that cannot be decomposed or factored further are used to construct composite services of appropriate granularity, writes Doug Barry. How many times have you read a statement like that related to the design of a service-oriented architecture? How many times have you been given a rigorous definition of atomicity – that condition where processes cannot be decomposed further? Barry guesses your answer to the first question is something along the lines of "too many times to count" and your answer to the last question might very well be "rarely or not at all." In an article on atomicity, Barry seeks to provide a rigorous definition, and a way to determine the correct granularity of services based on atomic processes. http://searchsoa.techtarget.com/tip/0,289483,sid26_gci1354005,00.html