1. A computer system including at least one composite system type for specifying a dynamic behavior of an application system, each said at least one composite system type comprising: one of an exit condition set and an exit function, wherein said exit condition set includes at least one exit condition, each said exit condition including a pair of an exit predicate that specifies a condition under which an instance of said at least one composite system type exits and an exit code that identifies said exit condition, and said exit function returns an exit code that identifies a condition under which an instance of said at least one composite system type exits; and at least one phased machine type, each said at least one phased machine type including at least one phase type, wherein each said at least one phase type comprises a subordinate system type and at least one transition, and wherein said subordinate system type includes one of a said at least one composite system type and a simple system type specifying a behavior type of a component of said computer system, and each said at least one transition includes a transition predicate for specifying a transition condition and a target for specifying a next phase to become active after the transition.