As said, a use case diagram needs to be simple and contains just a few shapes. A use case diagram in its simplest is a representation of a user’s interaction with the system which shows the association between the user and the various use cases where the user is involved. A use case diagram can determine different kinds of users of a system and the various use cases and will frequently be accompanied by other kinds of diagrams also.
Data flow diagrams can be split into logical and physical. They are also known as bubble charts. A logical data flow diagram focuses on the company and the way the company operates.
Usually, a use case is a comparatively large procedure, not an individual step or transaction. It is made up of a set of possible sequences of interactions between systems and users in a particular environment and related to a particular goal. It includes the functionality described in another use case as a part of its business process flow. The thing to consider is that the base use case ought to be in a position to execute a function on its own even if the extending use case isn’t called.
Use cases are primarily diagrams. They can illustrate the complexity of the system. Leading level use cases should always offer a comprehensive function required by means of an actor.