Modelling “services” in a uml class diagram

Question

In one on my software engineering homework i need to make the class diagram for modelling the problem of develop a system for a public library that can manage its loan service .

In this scenario i have an user , that can loan trough a loan service some library material (like audio dvd, video, text like book or something else). This is the rapid blueprint: Now my questions are:

Q1 : How can i model the association between user and the loan service? and , exactly, what is the name of this association?

Q2 : The loan service class only have one istance, because i think that the service is global for all user, so is correct to modelling this in the cardinality of the association?

Thank's in advance.

Answer 1

When you are to make an information model for the business operations of an organization (in your case, a public library), you have to identify all entity types involved (eg, users, media types, media items such as books and DVDs, loans, reservations, etc.) and the associations between them (eg, the class User would be associated with Loan ).

But you don't include a class for the organization itself (or its information system) in the model. Consequently, do not include a class for "loan service".

This approach results in an information design model that is the basis for deriving both an OOP class model for defining model classes (also called entity classes ) and a database table model (eg, for defining a MySQL database schema).

The model/entity classes provide the foundation for your app or IS.

Depending on your app development approach (eg, the chosen framework), you may have to design other classes (eg, for the user interface), but, compared to the model/entity classes, they are less fundamental.