Construct a data model using an UML class diagram to support a part of an online

team project application: TeamRabbit $($TR$).$ This is a drastically simplified system

that does not support many functions. Make reasonable assumptions.

The basic idea is to support teams to define, store, access, label, and update

projects and sub$-$projects. Access to the system may be made through multiple

types of devices such as computers, smartphones, web services, etc.

Users must be registered as TR members to use TR$.$ The system should store the

last name, first name, a unique screen name, and an optional working email

address for every member. The email address does not need to be unique. A unique

member id is assigned by the system and the start time of the member should be

recorded. A member may be referred by another member to join TR$,$ and the

referrer should be recorded.

Each member must have a username and a password to access TR$.$ However, an

account may be used by a person other than a TR member, such as a TR staff or a

TR system administrator. The management and administration module of the

system is not modeled in this assignment.

A member can create any number of teams. The creator of a team is known as the

owner of the team. Each team may also have managers who have heightened

privileges relative to other team members. However, only the owner can change

the managers of a project. The owner can also be a manager. A project can have

any number of members. The time when a TR member joins a team should be

recorded.

A member may have many roles in a team. Some of these role types are predefined

by TR$,$ for example, librarian, developer, team leader, supervisor, consultant, etc.

They are standard role types. Some roles are team$-$specific and can be defined by a

manager of the team. For example, a software team, S$1,$ may define the team

roles: modeler, programmer, technical writer, etc. When a team$-$specific role is

defined, an optional description and a creation time should be stored together with

the role name. The manager who defined the role should also be noted. Every role,

standard or user$-$defined $($team$-$specific$),$ has a role level. The role level is an

integer with a definition. Many roles can have the same role level.

A team has a unique id$.$ The team$$s name should be stored with the team creation

time and an optional description. A team has any number of projects. A project has

a name and a description. A project may have any number of sub$-$projects. There is

no limit on the number of levels of sub$-$projects. A project can be created by any

team manager. The creator of a task should be noted. A project may have an

expected completion time and an actual completion time. A program may be

assigned to a team member. The creator and the assignee may or may not be the

same person.