1-1 ROPES Rapid Object-Oriented Process for Embedded Systems

1-2 ROPES process artifacts

1-3 The ROPES Macro Cycle Analysis –Requirements AnalysisRequirements Analysis –Systems Analysis/EngineeringSystems Analysis/Engineering –Object AnalysisObject Analysis Design –Architectural DesignArchitectural Design –Mechanistic DesignMechanistic Design –Detailed DesignDetailed Design Translation Testing

1-4 Analysis Identification of all aspects of the product that are required for correctness

1-5 Analysis Model Artifacts

1-6 Requirements Analysis Extracts requirements from customer as –use cases, scenarios –statecharts –constraints Activities –Create Use Case model –Identify and characterize External Events –Define behavioral scenarios (system dynamic behavior) –Identify constraints, required interfaces to other systems and performance constraints

1-7 Requirements Analysis (2) Determine large scale “clumps” and refine their behavior Identify actors in the external environment Identify the semantics and characteristics of the individual messages (including those that signal events) between the system and its actors Refine interaction protocols that use those messages Refine the interaction protocols, e.g. required sequences, pre- and postconditional invariants

1-8 Create Use Case Model –Identify Use Cases and associated Actors UC classification –primary –secondary –safety-related –Decompose UC’s with generalization, uses and extends relations

1-9 aPossibleUseCaseModel

1-10 Messages & Events Analyst has to –find use cases and actors –identify messages passing between the actors and the system

1-11 Identify and characterize External Events by Associated actor (sender, receiver) Arrival pattern (periodic, episodic) Arrival time of message –period and jitter (periodic msg) –min inter-arrival interval or burst length (episodic msg) Message response properties –deadline (for hard deadline msg) –average response time (for soft deadline msg)

1-12 Identify and characterize External Events (2) by State information –pre-condition for the message –protocol (acceptable message sequence) –message data –post-conditional invariants for the response

1-13 External Event List example

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1-15 Actors Actors may be human users or externally visible subsystems and devices, such as sensors and actuators Common mistake to assume that actors must be people

1-16 Actors (2) Whether the actor is a device used by a human or the human itself depends on the scope of the system. If the system development includes the development of devices that interact with a human, then the human is the actor. If the system must interact with existing (or separately supplied) devices that are, in turn, used by human users, then the interface devices are the actors because they are the first thing outside the system scope that actually interacts with the system.

1-17 Messages During Analysis identify the semantics and characteristics of the individual messages (including those associated with signaling the occurrenceof events) that pass between the system and its set of actors A message is an abstraction of the exchange of information between a sender and a receiver

1-18 Messages (2) Have semantic content, i.e. the meaning of the message, e.g. –”the current temperature is 576 degrees” sensor –”insert the control rod” actuator Have structure, also called signature Usually a list of parameters during requirements analysis

1-19 Messages (3) Pre- and postconditional invariants, which are ontological states assumed to be true prior to sending and after receipt of a message Important in systems where –messages occur in one of a set of predefined sequences or –the system’s response to a message varies based on its state

1-20 Messages, Events Events can precipitate the sending of a message An event is an occurrence in space and time, which has significance to the system

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1-22 Assignment Nr 2 (1) Task(s): Revise/Modify the Use Case diagram for the MySSe Project from the previous assignment. Take into account that the hardware is not within the scope of the project, i.e. the system boundary (and other elements, too) should be modified according to the fact that the system you develop is just the software, even if it is very closely coupled to the car HW and not the complete racing car. Identify and characterize External Events as described in this presentation and fill a table of similar format than found in the slide “External Event List example”

1-23 Assignment Nr 2 (2) Deadline: (Wednesday) 10:00 Grading: The assignment affects the grading of the exam by -1, 0, or +1 “assignment points”. –-1: assignment not done or clearly inferior to the requirements. –The conversion between ““assignment points” and exam points will be decided upon later.

1-24 References Douglass, Bruce Powel. Doing Hard Time: Developing Real-Time Systems with UML, Objects, Frameworks, and Patterns. New York: Addison-Wesley, 1999.

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1-26 Behavior, event, signal This was not presented, it’s just extra information for those who would like a bit more insight

1-27 behavior The term behavior refers to the observable effects of an operation or an event, including its results.operationevent Behavior refers to the ways in which things change. Functional aspect: what the object does Classification: –Simple behavior an object performs services on request and keeps no memory of previous services –State/State-driven/Reactive behavior

1-28 event An event is a noteworthy occurrence that has a location in time and space. Within a state machine, the occurrence of an event can trigger a transition.state machinetransition An internal event passes between objects in the system; an external event passes between the system and an actor.objectactor Within the UML, there are four kinds of events: –call eventscall events –change eventschange events –signal eventssignal event –time eventstime event

1-29 Kinds of Events

1-30 call event A call event is an event that represents the dispatch of an operation.eventoperation

1-31 change event A change event is an event that represents the satisfaction of a Boolean expression in response to a change to one or more of the values it references.eventBoolean expression A condition becoming true is shown with the keyword when followed by a Boolean expression

1-32 signal event A signal event is an event that represents an object's reception of a signal.eventobject signal

1-33 signal A signal is a specification of an asynchronous stimulus communicated between instances. The receiving instance handles the signal by a state machine. The term signal is a keyword that refers to a named object that is dispatched asynchronously by one object and rec eived by another object.keyword nameobject

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