1. Information System Design
Lab 2

2. Lab Objectives Relationships in Use Cases Include. Extend.
Generalization.

3. Relationships in Use Cases
Use cases share different kinds of relationships. A relationship between two use cases is basically a dependency between the two use cases.
Use case relationships can be one of the following:
Include .
Extend .
Generalization.

4. Include Relationship Assume we have use case X and use case Y .
When a use case is depicted as using the functionality of another use case in a diagram, this relationship between the use cases is named as an include relationship
Assume we have use case X and use case Y .
The include relationship from X to Y indicates that the process of doing X always involves doing Y.

5. Include Relationship
An include relationship is depicted with a directed arrow having a dotted shaft. The tip of the arrowhead points to the child use case and the parent use case is connected at the base of the arrow.
Sometime the word uses is used instead of include
X has Y as a part of its task

6. Example
Hence, whenever the "Make appointment" use case executes, the business steps defined in the "Validate patient records" use case are also executed.

7. Extend Relationship
extend relationship between two use cases, the child use case adds to the existing functionality and characteristics of the parent use case .
Assume we have use case X and use case Y .
The extend relationship from X to Y indicates that the process of doing X special case behavior of the same type as the more general process Y.

8. Extend Relationship
An extend relationship is depicted with a directed arrow having a dotted shaft, similar to the include relationship. The tip of the arrowhead points to the parent use case and the child use case is connected at the base of the arrow . Y
<<extend>> X

9. Example
The "Perform Pathological Tests" use case enhances the functionality of the "Perform medical tests" use case. Essentially, the "Perform Pathological Tests" use case is a specialized version of the generic "Perform medical tests" use case.

10. What is the differences between
include and extends?
“X include Y “indicates that the task “X” has subtask “Y” .
“X extends Y” indicates that “X” is task of the same type as ”Y” but “X” is a special , more specific case of doing “Y” .

11. Generalization Relationship
The generalization link is an informal way of showing that one use case is similar to another use case, but with a little bit of extra functionality.  One use case inherits the functionality represented by another use case and adds some additional behavior to it.
generalization relationship is also a parent-child relationship between use cases. The child use case in the generalization relationship has the underlying business process meaning, but is an enhancement of the parent use case.

12. Generalization Relationship
An generalization relationship is shown as a directed arrow with a triangle arrowhead. The child use case is connected at the base of the arrow. The tip of the arrow is connected to the parent use case.

13. Example
Paper
This would mean that in future you might choose to store patient records in a computerized file instead of as paper documents without impacting other business actions.

14. Note
generalization relationship between use cases, this implies that the parent use case can be replaced by the child use case without breaking the business flow.
extend relationship between use cases implies that the child use case enhances the functionality of the parent use case into a specialized functionality. The parent use case in an extend relationship cannot be replaced by the child use case.

15. Exercise1
Draw a use diagram for on line CD catalog .The system has on-line customer . The customer can browse the catalog, search for CD , add a CD to the order , view the order details , and place the order.
Both “ view order details” and “place order” use “calculate order total”.

17. Exercise2
Draw use Diagram for Airline reservation system .the system allow the ticket clerk to do the following tasks:
check in passenger through weight the luggage and assign seat .
Add reservation by checking for available seats and record passenger information.
cancel reservation so must modify seat chart
the company Provide seats nearby aisle and other nearby window and is determined according to the request of the passenger