Hibernate version: 3.2.6

Mapping documents: None yet.

Name and version of the database you are using: MySQL 5.0.67

I'm looking for advice on how to model a system.

I have Users, Events, and Roles.

Users control many Events, and Events can be controlled by many Users.

Roles restrict how much control a User has over a given Event. Users can have many roles (per Event). Roles are used by many Users.

The Roles table will have a mostly-unchanging list of Roles, for example: "view_widgets", "print_reports", "edit_attendants", basically an ACL of possible things a User can do to an Event.

So I want a User to be associated with many Events, and for each of those Events, have a set of Roles.

How best to describe this in terms of database table structure? A single join table, or two?

How best to describe this in Hibernate using annotations to describe the relationships between User, Event and Role?

Note: A User can only control one Event at a time, in the web interface.

Who needs to know what:

Users need to know
-- Which Events can I control?
-- Which Roles do I have for the Event I'm currently controlling

Events need to know
-- Which Users can control me?

Roles don't need to know anything.

Any responses are much appreciated, even to tell me that I shouldn't be doing what I've described so far!

Without Hibernate, I would do something like:

User:


Event:


Role:


Using a single join table:



This would say "eric can add attendants and apply payments to the golf trip".

How do I implement this using Hibernate?

Here's maybe a more direct question. How can I model a Map which is keyed by an entity, and each value is a Set of other entities?



So for a User u, and Event e,