Question

Name the entities activities events and state variables for library

Answer 1

The components of the system are as given below:

• Entities: An entity is an object of interest in the system. In other words any person or a thing which is given more priority in a system. For example in system of communication the most preferable thing is message.

• Attribute: An attribute is a property of entity.

• Activity: An activity represent time period of specified length.

• Event: An event can be defined as an instantaneous occurrence that might change the state of system.

• State variables: A state variables is one of set of variables.

Answer 2

Entity: Customer
Attributes: account
Activities: Number of books availed, Number of books returned
event:  Arrival, Departure
State variables: Number of kids, Number of adults