The exo.platform.services.organization package has five main components: user, user profile, group, membership type and membership. There is an additional component that serves as an entry point into Organization API - OrganizationService component that provides the handling functionality for the five components.
The User component contains basic information about the user, such as username, password, first name, last name, and email. The User Profile component contains extra information about a user, such as user's personal information, and business information. You can also add additional information about a user if your application requires it. The Group component contains a group graph. The Membership Type component contains a list of predefined membership types. Finally, the Membership component connects a User, a Group and a Membership Type.
A user can have one or more memberships within a group, for example: the user A can have two memberships: 'member' and 'admin' in the group /user. A user belongs to a group if he has at least one membership in that group.
Exposing the Organization API to developers who have access to the handler objects provided by the OrganizationService component. These handler objects are used to manage each of the five components, including UserHandler, UserProfileHandler, GroupHandler, MembershipTypeHandler, and MembershipHandler.
The five central API components are really designed like persistent entities, and handlers are really specified like data access objects (DAO).
Organization API simply describes a contract, meaning it is not a concrete implementation. The described components are interfaces, allowing different concrete implementations. Practically, it means that you can replace the existing implementation with a different one.