Sequence Diagram vs Usecase Diagram

Question

I have build a usecase diagram for hotel reservation

Should i build a sequence diagram for each usecase in the usecase diagram, or can i summarize multiple usecase in a single sequence diagram?

Answer 1

A use case diagram shows how use cases and actors relate to each other and gives a functional system overview. Use cases boil the system down to their added values and do not show how these are achieved.

Any scenario of a use case is graphically represented in an activity diagram where the single steps occur as actions.

A sequence diagram is used to show how objects communicate.

Usually you derive classes and relate them to actions of the use case activities. So when you create a sequence diagram it highlights a certain aspect of the whole system. This highlight is usually spot on and not a floodlight. Putting multiple use case scenarios in a single SD would for sure simply blind any reader instantly.

Answer 2

Usecase diagram

Use case diagrams show business use cases, actors, and the relationships between them. The relationships between actors and business use cases state that an actor can use a certain functionality of the business system. You will not find any information about how or in what chronological sequence these services are rendered

sequence diagram

A sequence diagram can map a scenarios described by a use case in step by step detail to define how objects collaborate to achieve your application's goals.

Here is the diagram , which will clear things better to you