The helpdesk module will be noted “HD” for ease of writing.

• a USER is a person experiencing issues and requesting help from the helpdesk
• a Customers is a person or entity owning a HD Contracts to access the helpdesk
• a HD Techs is a person working on the helpdesk to solve USERs' problems
• an ATTENDANT is a person taking calls over the phone or receiving them by fax or mail, and allocating HD Ticketss to USERs
• a HD Contracts is the set of terms under which a Customers has access to the helpdesk, and its current state vector
• a HD Tickets is the initial entry point for an issue opened by a USER
• a HD Ticket Followups represents additional action on a HD Tickets after it has been created.

The following is a UML class diagram of these entities, prior to physical modeling:

HD makes use of two vocabularies:

• HD Status : a list of the status values defined by the HD site admin. HD only requirement is that the first value defined in the taxonomy represents the state a ticket is in where the issue no longer needs anything done.
• HD Severity : a list of the severity levels defined by the HD site admin. HD makes no use of this.

HD tickets can link to an e-commerce transaction, allowing for faster resource allocation decisions on tickets submitted without a support contract, and for code-based generation of contract by the e-commerce module, which could be useful for the automatic setup of warranty HD access.

HD access relies on drupal permissions (admin/access). Three composite levels of permissions are defined:

• Helpdesk > User : this represents the rights of the typical USER: can create tickets, submit followups, view own tickets and followups
• Helpdesk > Customer : this represents the rights of the typical Customers: can check their contract status (billing), suspend/reactivate their contract if this feature has been enabled, check all support tickets and followups for the users bound to them
• Helpdesk > Tech : this represents the most extensive set of rights, typical of HD Techs: can do all a Customers can, but also create/revoke contracts, modifiy their values, create tickets, and followups, etc.

It is expected that admins of site using HD will define 3 roles and give each role the set of permissions matching these descriptions: role user gets “Helpdesk > User”, role customer get “Helpdesk > Customer” and usually “Helpdesk > User” to be able to function as a user too, and role tech gets all three permissions, for situations where there are techs besides the actual Drupal admin.