UML Descriptive question Chapter-04

Chapter-04

Modeling Concepts

 1. What is the difference between model and diagram?
Ans.
Model: Like any map, models represent something also. Models are usually both abstract and visible. They are useful in several different ways, precisely because they differ from the things that they represent-
a) A model is quicker and easier to build.
b) A model can be used in simulations to learn more about the thing it represents.
c) A model can evolve as we learn more about a task or problem.
d) We can choose which details to represent in a model and which to ignore. It is an abstraction.
e) A model can represent real or imaginary things form any domain.

Diagram: Diagrams are used to build models of system in the systems in the same way as architects use drawings and diagrams to model buildings. Diagrammatical models are used extensively by system analysts and designers in order to-
a) Communicate ideas
b) Generate new ideas and possibilities
c) Test ideas and make predictions
d) Understand structures and relationships A model provides a complete view of a system at a particular stage and form a particular perspective.

2. What are the basic elements of UML model diagram?
Ans. UML diagrams are made up of four elements-
a) Icons
b) Two dimensional symbols
c) Paths
d) Strings

UML diagrams are graphs composed of various kinds of shapes, known as nodes, joined together by lines, known as paths.

Different models present different views of the system. Booch et al (1999) suggest five views to be used with UML
1. The use case view
 2. The design view
3. The process view
4. The implementation view
5. The development view

 3. What is the UML notation for each of the following package, sub-system and model?
Ans.

 Fig: UML notation for packages, sub-systems and models.

 4. Draw a simple Activity diagram.  
 Activity Diagram:

Activity diagram can be used to model different aspects of a system. At a high level, they can be used to model business activates in an existing or potential system. Activity diagram can be used for the following purpose:
1) To model a task
2) To describe a system function that is represented by a use case.
3) In operation specifications, to describe the logic of an operation.
4) In USDP to model the activities that make up the life cycle.

5. Guard Condition :
Ans. Guard condition is a Boolean expression associated with a transition that is evaluated at the time the event fires. The transition only takes place if the condition is true. A guard condition is a function that may involve parameters of the triggering event and also attributes and links of the object that owns the state chart.  

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