UML Descriptive question Chapter-05

Chapter-05 

Requirements Capture & Requirements Analysis

 1. List the name of the fact finding techniques. 
Ans. There are 5 main fact finding techniques that are used by analyst to investigate requirements-
 a) Background reading 
b) Interviewing
c) Observation
d) Document Sampling
e) Questionnaires

Advantage & disadvantage of fact finding technique:
a) Background reading:
(+) Background reading helps the analyst to get on understanding of the organization before meeting the people who work there
(-) written document often do not match the reality, they may be out of date or they may reflect the official policy on matter that are dealt with differently in practice

b) Interviewing:
(+) Personal contact allows the analyst to be responsive and adapt to what the user says. Because of this interviews produce high quality information.
(-) Interviews are time consuming and can be the most costly form of fact gathering.

c) Observation:
(+) Observation of people at work provide firsthand experience of the way that the current system operates.
(-) Observation requires a trained and skilled observer for it to be most effective.

 d) Document Sampling:
(+) Can be used to gather quantitative date such as the average number of lines on an invoice.
(-) If the system is going to change dramatically. existing documents may not reflect how it will be in future.

 e) Questionnaires :
(+) An economical way of gathering data from a large number of people.
(-) Good questionnaires are difficult to construct.

 2. What is use case? What is the purpose of use case? 
Ans. Use cases are descriptions of the functionality of the system from the users’ perspective. Use case diagrams are used to show the functionality that the system will provide and to show which users will communicate with the system in some way to use that functionality.

Purpose: Use cases are supported by behavior specifications there specify the behavior of each use case either using UML diagrams, such as collaboration diagrams or sequence diagrams or in text from as use case descriptions. Textual use case description provides a description of the interaction between the users of the system, termed actors and the high level functions within the system the use case.

 3. What is Stereotypes? Describe include & extend. 
Ans. Stereotype: A stereotype is a special use of a model element that is constrained to behave in a particular way Stereotypes can be show by using a keyword. Such as ‘extend’ or ‘include’ in matched quillements like <extend>. Stereotype can also be represented using special icon. The actor symbol in use case diagrams is a stereotyped icon- an actor is a stereotyped class and could also be shown as a class rectangle with the stereotype <actor> above the name of the actor. 

 <extend> is used when we wish to show that a use case provides additional functionality that way be required in another use case. 

 <include> applies when there is a sequence of behavior that is used frequently in a number of use cases and we want to avoid copying the same description of it into each use case in which it is used.

Requirements Analysis

4. What is a collaboration diagram?
Ans. A collaboration diagram shows an interaction between objects and the context of the interaction in terms of the link between the objects.

5. Define boundary class, entity class and control class?
Ans. Boundary class: Boundary class is a stereotyped class that provides an interface to users or other system.
Entity class: Entity class is a stereotyped class that represents objects in the business domain model.
Control class: Control class is a stereotyped class that controls the interaction between boundary classes and entity classes.

6. Distinguish between link and association.
Ans. Link: Link is a connection between objects and instance of an association.
Association: - Association is a logical connection usually between different classes although in some circumstances a class can have an association with itself. An association describes possible links between objects and may correspond either to logical relationships in the application domain or to message paths in software.

7. What is multiplicity and why can it be called a constraint?
Ans. Multiplicity: Multiplicity devotes the range of values of the members of objects that can be linked to a single object by a specific association. It is a constraint because it limits the behavior of a system. If a client can have only one staff contact it should be impossible to link a second.

8. How does a collaboration diagram differ from class diagram?
Ans. A collaboration diagram shows only those classes that collaborate to provide the functionality of a particular use cases (or operation); the links that are shown are those that are required for that purpose. a class diagram typically shows all the classes in a particular package and all the associations between them.  

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