Object Oriented Design - Lecture 3: Use Cases

This post is the note of lecture 2 of the course "Object Oriented System Analysis and Design". Videos can be viewed at https://www.youtube.com/watch?v=ODeQ0rF59kI&index=3&list=PL6XklZATqYx9dj72MKG6wLYjljeB2odra.

Lecture 3

1.Use cases definition

1. Definition: use case is an activity that system performs, usually in response to a request by a user.
2. Use cases define functional requirements.
3. Two techniques to identify use cases:
1. user goal technique
2. event decomposition

2.User goal technique

Seldom use. 

3.Event decomposition technique

1. Type of Events
1. external event: an event that occurs outside the system, usually initialized by an external agent/actor.
2. internal event:
1. temporal event: ana event that occurs as a result of reaching a point in time (e.g., 
2. The decomposition process:
1. Identify the event that occurs to which the system must respond.
2. For each event name a use case (verb-noun) that describes what the system should do
3. CRUD decomposition: Create, Read/Report, Update, Delete
   Steps:
1. Identify all domain classes (e.g., Customer, Seller, etc)
2. Check whether we need CRUD functions
3. When integrating applications, make sure it is clear which application is responsible for adding and maintaining the data, and which system merely uses the data.
3. Use case diagram