Changes the user connected to the Rules Engine from the current user to the user specified by the username value.
Calling this method is effective only if the Deployment Configuration parameter 'RdbmsConnect' has been set to 'auto'.
The required username is the database user name of the user that must be connected instead of the current user.
The required password is this new user's password.
The required key value must be the empty string ( '' ). This option is currently not used but will serve in the future to allow logging or extra user authentication checks. For web applications, for example, the IP number could be passed using this option.