19. A program of instructions stored on a non-transitory computer-readable storage medium which, when executed, causes a computer to perform: obtaining the instructions from the program, the instructions from the program having been generated in an intermediate language, by a compiler, to cause processing of an execution sequence according to a specification of a model, the model specification encoded using a model notation that is distinct from the intermediate notation; and executing the obtained instructions from the program, wherein the instructions from the program are encoded in a markup language notation by the compiler and are selected by the compiler from allowable instructions of the intermediate language, the markup language notation being distinct from the intermediate language, the allowable instructions of the intermediate language comprising: an event instruction for receiving an inbound event; an assignment instruction for assigning a value; a branch instruction for conditional transfer to a different one of the instructions; an emit instruction for specifying that an outbound event is to be emitted; a terminate instruction for specifying that a current execution context object is to be terminated; and a fan-out instruction for at least one of specifying event correlation and enabling a context switch, the context switch causing a particular execution context object to be used as the current execution context object.
19. A program of instructions stored on a non-transitory computer-readable storage medium which, when executed, causes a computer to perform: obtaining the instructions from the program, the instructions from the program having been generated in an intermediate language, by a compiler, to cause processing of an execution sequence according to a specification of a model, the model specification encoded using a model notation that is distinct from the intermediate notation; and executing the obtained instructions from the program, wherein the instructions from the program are encoded in a markup language notation by the compiler and are selected by the compiler from allowable instructions of the intermediate language, the markup language notation being distinct from the intermediate language, the allowable instructions of the intermediate language comprising: an event instruction for receiving an inbound event; an assignment instruction for assigning a value; a branch instruction for conditional transfer to a different one of the instructions; an emit instruction for specifying that an outbound event is to be emitted; a terminate instruction for specifying that a current execution context object is to be terminated; and a fan-out instruction for at least one of specifying event correlation and enabling a context switch, the context switch causing a particular execution context object to be used as the current execution context object. 21. The program of instructions according to claim 19 , wherein the model specification is a message-driven model specification.