How does Joomla load user data in login when I've disabled it's authentication plugin? -

i built joomla authentication plugin authenticates users through web services made in java, , user data stored in oracle database different joomla's own database both in structure , data.

i've create user component far registration, again through web services, register user object on joomla too, project not important @ can stay.

i've disabled joomla's own authentication plugin , enabled mine.

what happens:

1. user registers successfully
2. their data saved both in oracle database through web services , in joomla's db.
3. on user login authenticate user through web services only.
4. once user logs in can see "joomla" data on site.

now question is: how can joomla know user did log in if authentication not done joomla? load user data, on successful authentication, selecting username?

thanks in advance.

as stated in pt. 2, user data - independent authentication method - stored in joomla!'s own user repository. repositiory (database table) still used keep user relevant data. difference authentication itself, ie., determination whether credentials valid or not.