OMT(Object ModelingTechnique) It is a methodology that combines the views of a modeling system. Three types of model used. (1) Object Model (2) Dynamic Model (3) Functional Model
Object Model It represents static, structured, data aspect of the system. Structure of a system contains following information-• Their Identity• Their Relationship to other objects• Their Attribute.• Their Operations. Object model provides the essential Framework into which Dynamic and Functional model can be placed. It is represent (Graphically) by Object Diagram
Dynamic Model It represents the- Temporal Behavioral and, Control aspects of the system.
Functional Model It represents the Transformational (Functions) aspects of the system. Describe those aspect of the system concerned with Transformation of values. It concerned with following-1. Functions2. Mapping3. Constraints and4. Functional Dependency Represented by – DFD, CFD
Dynamic Model Describes the aspect of a system concerned with Time and Sequencing of Operations-1. Events that mark changes.2. Sequence of Events.3. State that defines the context for event and4. The organization of events and states. It is represented by the a State Diagram.
Dynamic Model………… Summary The dynamic model shows the time-dependent behavior of the system and the objects in it. Begin dynamic analysis by looking for event, externally visible stimuli and responses. The dynamic model is important for interactive systems, but insignificant for purely static data repository, such as database.
Dynamic Model…… State &Events State The attribute values and link held by an object are called its state. Events- An individual stimulus from one object to another as called an event. OR An event is something that happens at a point in time. ex. User depress left button of a mouse. Overtime, the object stimulate each other, resulting in a series of changes to their states.
Dynamic Model…… Events Concurrent Event- Two events that are casually unrelated are said to be con current events. Points to Ponder:1. In a modeling system, we don’t try to establish an ordering between concurrent events, because they can occur in any order.2. An event is a one way function transmission of information from one object to another. It is not like a subroutine/function that returns a value.3. Every event is a unique occurrence, but we group into event class, & give each event class a name to initialize a common structure and behavior.
Dynamic Model…… Events For Exp.(Event class and attribute)1. airplane flight depart (airline, flight no, city)2. Mouse button pressed (button, location)3. Input string enterd (text)4. Phone receiver lifted5. Digit dialed (digit)6. Engine speed enters danger zone
Dynamic Modeling….. State Diagram The pattern of events, state and state transitions for a given class can be abstracted and represented as state diagram.1. A state diagram is network of states and events.2. The state diagram, one state diagram for each class with important dynamic behavior and shows the pattern of activity for an entire system.3. Each state machine executes concurrently and can change state independently4. The state diagram for the various classes combine into a single dynamic model via shared events.
Dynamic Modeling….. The following steps are performed in constructing a dynamic model1. Prepare scenarios of typical interaction sequences2. Identify events between objects3. Prepare an event trace for each scenario4. Build a state diagram5. Match events between objects to verify consistency
Dynamic Modeling….. Scenerios & EventTraces Sequence of events that occur during one particular execution of a system. The scope of scenarios can vary-1. It may include all events in the system.2. Or, it may include only those events impinging on or generated by certain objects into the system.3. Or, it can be a historical records.