Types of interactions that can be represented in a model:
• Modeling user interaction is important as it helps to identify user requirements.
• Modeling system-to-system interaction highlights the communication problems that may arise.
• Modeling component interaction helps us understand if a proposed system structure is likely to deliver the required system performance and dependability.
Use cases were developed originally to support requirements elicitation and now incorporated into the UML. Each use case represents a discrete task that involves external interaction with a system. Actors in a use case may be people or other systems. Use cases can be represented using a UML use case diagram and in a more detailed textual/tabular format.
Simple use case diagram:
Use case description in a tabular format:
|
Use
case title
|
Transfer
data
|
|
Description
|
A
receptionist may transfer data from the MHC-PMS to a general
patient record database that is maintained by a health authority.
The information transferred may either be updated personal
information (address, phone number, etc.) or a summary of the
patient's diagnosis and treatment.
|
|
Actor(s)
|
Medical
receptionist, patient records system (PRS)
|
|
Preconditions
|
Patient
data has been collected (personal information, treatment
summary);
The receptionist must have appropriate security permissions to access the patient information and the PRS. |
|
Postconditions
|
PRS
has been updated
|
|
Main
success scenario
|
1.
Receptionist selects the "Transfer data" option from the
menu.
2. PRS verifies the security credentials of the receptionist. 3. Data is transferred. 4. PRS has been updated. |
|
Extensions
|
2a.
The receptionist does not have the necessary security
credentials.
2a.1. An error message is displayed. 2a.2. The receptionist backs out of the use case. |
