What happens when you login to Apps?

Firstly and surely there is a URL for oracle applications that is structured possibly in below format, although it can vary from version of apps.
http://machinename:portnumber/OA_HTML/US/ICXINDEX.htm
http://machinename:portnumber /oa_servlets/AppsLogin

When you join an Oracle Apps development team for an employer, you will first be given URL of the development environment.

In any Oracle Apps implementation project (assuming it has gone live), there are minimum of three environments, each with different URL's and different database instances.

These are:-
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Development environment
Testing environment
Production environment

You will most probably, as a techie, be given url,username ad password of the development environment.

What happens when you login(no advanced info here):-
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A. Your login gets authenticated against a table named fnd_user for your username and password. The screen below is where username and password defined. This screen is called user definition screen. Only system administrators have access to this screen.

B. As you can see above, this username xxpassi is attached to two responsibilities (this will be discussed in details in latter training lesson). It is this assignment to the responsibility that controls what a logged in person can do and can't do. In layman’s words, a responsibility is a group of menu.
It will prompt you to change your password, to a value different than that assigned by System Administrator.

You might be prompted to install jinitiator…..just keep clicking OK…OK for all Jinitiator messages). Effectively, what I mean to say is that you do not need to download jinitiator from anywhere; Oracle will do this automatically (provided your DBA’s got this cofig’ed) for you during your first logon attempt from the PC. Once your jInitiator gets installed .
Oracle internally uses a login named GUEST, prior to invoking validation of actual username. Some people regard this as a security threat, but it isn’t. Your DBA’s can change the “guest” password from its default value after installation.

Oracle uses a DB User account named applsyspub to which it first connects during validation of LOGIN. This user account has very restricted privileges and has access to below objects (primarily for authentication purposes):-
FND_APPLICATION
FND_UNSUCCESSFUL_LOGINS
FND_SESSIONS
FND_PRODUCT_INSTALLATIONS
FND_PRODUCT_GROUPS
FND_MESSAGES
FND_LANGUAGES_TL
FND_APPLICATION_TL
FND_APPLICATION_VL
FND_LANGUAGES_VL
FND_SIGNON
FND_PUB_MESSAGE
FND_WEBFILEPUB
FND_DISCONNECTED
FND_MESSAGE
FND_SECURITY_PKG
FND_LOOKUPS