Describes state and events. (C++)

the attribute values and links held by an object are called its state.

The object simulate each other, resulting in a series of changes to their state.

“an individual stimulus from one object is another is an event”

The response to an event depends on the state of the object receiving it, and can include a change of a state or the sending of another event to the original sender or to a third object, the pattern of events, states and state transitions for a given class can be abstracted and represented as a state diagram.

Events   -

·     An event is something that happens at a point in time. For example user depresses left button of flight 1223 departs from Kathmandu.

·     An event has no duration

·     And event  is simply an occurrence that is fast compared to the granularity of the time scale.

·     One event may be logically precede or follow another.

·     Two event may be unrelated.

·     Two evens are casually related.

·     Two events are casually unrelated are said to be concurrent. They have no effect on each other.

·     In modeling a system use do not try to establish an ordering between concurrent events because they can occur in any order.

·     An events is one way transmission of information from one object to another,

·     An object sending an events to  another objects may expect a reply, but the reply is a separate event is under the control of second objects.

·     Every events is unique occurrence,but can grouped in a class if they all are of same type.

·     An events conveys information from one object to another  .

State

·     A states is an abstraction of the attribute values and links of an object i.e. the state of bank is solvent or insolvent.

·     A states specifies the response of the object to input events.

·     The response into of an object to an event may include an action or a change of state by the object.

·     A state corresponds to the interval between two events received by an object.

·     Events represent points in time.

·     State represent intervals of time.

·     A state has duration, it occupies an interval of time. A state if often associated with a continuous, activity, such as a ringing of a telephone, such as a flying from malaysiya to bankok.

·     Events and states are dual of one another.

·     A state separate two events.