1. Software design and architecture
Lecture#4

2. Sequence diagrams
Sequence diagrams are used to show a design team how objects in a program interact with each other to complete tasks
Boxes
lifelines
Solid line arrows
Dotted line arrows
Small rectangles
Actors

3. Example

4. Example(cont’d)

5. State diagrams
technique used to describe how systems behave and respond. They follow the states of a system or a single object and show changes between the states as a series of events occur in the system.
State
Start
Terminate
Active
State name
Variables
Activity

6. Transitions
Arrows indicate transitions from one state to another. Transitions are typically triggered by an event. This event is generally described above the arrow.
Event[condition]/action
The transition and action happens from a given state if the event occurs and the condition is true.