UML Sequence Diagrams

During the requirements analysis phase, the system can be treated as a single "black box", which means that we can look at the system's behavior (what it does) without explaining how it does it. Read this section to see an example of a simplified trace diagram that shows only system input events. This is called a system sequence diagram.

15. Conclusion

Relating the three models used so far in this unit, it can be observed that:

i. Use cases suggest the system input events and system sequence diagram. 

ii. The system operations are then identified from system sequence diagrams. 

iii. The effect of the system operation is described in contract within the context of the conceptual model.