= LID Servlet Request Attributes =

Identity support in !InfoGrid makes use of request attributes according to the JEE specification. This enables application developers to consistently determine information about the current user simply by examining some pre-defined attributes in the incoming request.

As a REST-ful framework, !InfoGrid attempts to avoid session data as much as possible. Therefore, all identity-related attributes are stored in the incoming !ServletRequest, not a session object.

The following attributes are used:
 * `CLIENT_ID`: identifier of the currently authenticated user if that user has been authenticated with a remote account, e.g. OpenID, regardless of whether or not the user is associated with a local !LidAccount
 * `CLIENT`: !HasIdentifier object (e.g. a MeshObject) representing the authenticated user if that user has been authenticated with a remote account, e.g. OpenID, regardless of whether or not the user is associated with a local !LidAccount
 * `ACCOUNT_ID`: identifier of the user's local `LidAccount`, if any
 * `ACCOUNT`: the user's local `LidAccount`, if any
 * `USER_ID`: identifier of the currently authenticated user. If the user has authenticated with the local !LidAccount, it holds the identifier of the local !LidAccount. If the user has authenticated with a remote account (e.g. OpenID), it holds the identifier of the remote account (regardless of whether or not it is associated with a local !LidAccount).
 * `USER_NICK`: user's nickname to be shown on web pages. 
 * `lid`: synonym of `USER_ID` (for compatibility reasons)

These attributes are typically only set if the user has been authenticated successful, and for the duration of the session afterwards.

See also:
 * [wiki:Docs/LidAccountModel LID Account Model].